Secretory IgA protects mucosal surfaces by which mechanism?

Preventing microbial adherence to the mucosa

Does secretory IgA fix complement?

No, sIgA does not fix complement

What is the structural form of secretory IgA?

A dimer joined by a J chain plus secretory component

What is the main function of secretory IgA in the oral cavity?

Mucosal surveillance, preventing microbial adherence

IgE antibody: what is its defining property?

It binds strongly to mast cells

What are the four mechanisms of self-tolerance (autotolerance)?

Clonal deletion, clonal anergy, active suppression (Tregs), sequestration of antigens

Contact dermatitis is which type of hypersensitivity?

Type IV (delayed-type hypersensitivity, DTH)

What triggers contact dermatitis at the molecular level?

A hapten binding covalently to a skin self-protein, forming a neoantigen

Metal braces, crowns, and dental fillings may induce which hypersensitivity?

Type IV (delayed-type) — contact dermatitis to the metal hapten

Give two examples of Type III hypersensitivity reactions.

Serum sickness and the Arthus reaction

What advantage does a killed/inactivated vaccine have over live-attenuated?

It can be safely given to immunodeficient patients

In which groups is live-attenuated vaccine contraindicated?

Immunodeficiency, pregnancy, and HIV

What are the four mechanisms of autotolerance involve?

Clonal deletion, clonal anergy, active suppression (Tregs), sequestration of antigens

During NK-cell ADCC of a virus-infected cell, what specifically induces the reaction?

IgG bound to a viral capsid protein on the target cell's plasma membrane

In a secondary CD8 cytotoxic (Tc) response, which cell presents the antigen to the CTL?

An MHC class I-expressing somatic (any nucleated) cell

In a secondary CD8 cytotoxic response, is the presenting cell a professional APC?

No - it is the infected somatic cell itself, not a professional APC

What kind of peptide do effector/memory CD8 CTLs recognize on the target cell?

Endogenous peptide on MHC class I

Tregs enforce clonal anergy through which molecular interaction?

Their CTLA-4 (CD152) binds CD80/CD86 (B7) on the APC

How does CTLA-4 remove costimulation from a T cell?

It outcompetes CD28 for B7 (CD80/CD86), denying the costimulatory signal

Does CD28 binding CD80/86 cause anergy or activation?

Activation (costimulation), not anergy

Oxygen-dependent killing by phagocytes is mediated by which agents?

Reactive oxygen intermediates (ROIs), nitric oxide (NO), and hypochlorous acid (HOCl)

What is the role of myeloperoxidase in phagocyte killing?

It is the enzyme that makes HOCl (not itself the reactive species)

A hapten binding to a skin self-protein induces what reaction?

Contact hypersensitivity / contact dermatitis

Contact dermatitis (from a hapten-modified self-protein) is which hypersensitivity type?

Type IV (delayed-type hypersensitivity, DTH)

Is hapten-induced contact dermatitis an IgE (Type I) reaction?

No - it is Type IV (cell-mediated)

What antibody causes hemolytic disease of the newborn (HDN)?

Incomplete (IgG) anti-D antibodies

Why can the maternal anti-D antibody reach the fetus in HDN?

It is IgG, the only class that crosses the placenta

Must the Rh-negative mother be sensitized for HDN to occur?

Yes - she must be previously sensitized to Rh-positive RBCs

Public flashcard deck · 500 cards

Immunology Final Master Study Deck

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Front
Secretory IgA protects mucosal surfaces by which mechanism?
Back
Preventing microbial adherence to the mucosa
Front
Does secretory IgA fix complement?
Back
No, sIgA does not fix complement
Front
What is the structural form of secretory IgA?
Back
A dimer joined by a J chain plus secretory component
Front
What joins the two monomers of secretory IgA?
Back
The J chain
Front
What is the main function of secretory IgA in the oral cavity?
Back
Mucosal surveillance, preventing microbial adherence
Front
Which immunoglobulin carries the secretory component?
Back
Secretory IgA
Front
Which IgA subclass is the preferred key for secretory component?
Back
IgA2
Front
IgE antibody: what is its defining property?
Back
It binds strongly to mast cells
Front
Does IgE fix complement?
Back
No
Front
Which hypersensitivity type does IgE mediate?
Back
Type I
Front
What are the four mechanisms of self-tolerance (autotolerance)?
Back
Clonal deletion, clonal anergy, active suppression (Tregs), sequestration of antigens
Front
Which cells mediate active suppression in self-tolerance?
Back
Tregs
Front
Which cytokines mediate hepatic acute-phase protein release?
Back
IL-1 and IL-6
Front
In the single-answer version, which cytokine is keyed for acute-phase protein release?
Back
IL-6
Front
Contact dermatitis is which type of hypersensitivity?
Back
Type IV (delayed-type hypersensitivity, DTH)
Front
In contact dermatitis (Type IV/DTH), which cells mediate the reaction?
Back
Th1 cells and macrophages
Front
What triggers contact dermatitis at the molecular level?
Back
A hapten binding covalently to a skin self-protein, forming a neoantigen
Front
Metal braces, crowns, and dental fillings may induce which hypersensitivity?
Back
Type IV (delayed-type) — contact dermatitis to the metal hapten
Front
Activation of complement causes tissue damage in which hypersensitivity type?
Back
Type III (immune-complex)
Front
Which cells arrive first in Type III hypersensitivity?
Back
Neutrophils
Front
What mediates the tissue damage in Type III hypersensitivity?
Back
Complement
Front
Give two examples of Type III hypersensitivity reactions.
Back
Serum sickness and the Arthus reaction
Front
Give an example of a privileged immunological site.
Back
The testis
Front
Suppression of Th1 by Th2 is mediated by which cytokine?
Back
IL-10
Front
What advantage does a killed/inactivated vaccine have over live-attenuated?
Back
It can be safely given to immunodeficient patients
Front
Can a live-attenuated vaccine be safely given to an immunodeficient patient?
Back
No, it cannot
Front
In which groups is live-attenuated vaccine contraindicated?
Back
Immunodeficiency, pregnancy, and HIV
Front
Which vaccine type gives the strongest cellular (cell-mediated) immune response?
Back
Live-attenuated vaccines
Front
What are the four mechanisms of autotolerance involve?
Back
Clonal deletion, clonal anergy, active suppression (Tregs), sequestration of antigens
Front
Which tolerance mechanism is broken in atopic (allergic) individuals?
Back
Immunological facilitation
Front
During NK-cell ADCC of a virus-infected cell, what specifically induces the reaction?
Back
IgG bound to a viral capsid protein on the target cell's plasma membrane
Front
Which NK receptor engages the Fc of surface-bound IgG during ADCC?
Back
CD16 (FcγR)
Front
In a secondary CD8 cytotoxic (Tc) response, which cell presents the antigen to the CTL?
Back
An MHC class I-expressing somatic (any nucleated) cell
Front
In a secondary CD8 cytotoxic response, is the presenting cell a professional APC?
Back
No - it is the infected somatic cell itself, not a professional APC
Front
What kind of peptide do effector/memory CD8 CTLs recognize on the target cell?
Back
Endogenous peptide on MHC class I
Front
Tregs enforce clonal anergy through which molecular interaction?
Back
Their CTLA-4 (CD152) binds CD80/CD86 (B7) on the APC
Front
What is the alternative name for CTLA-4?
Back
CD152
Front
How does CTLA-4 remove costimulation from a T cell?
Back
It outcompetes CD28 for B7 (CD80/CD86), denying the costimulatory signal
Front
Does CD28 binding CD80/86 cause anergy or activation?
Back
Activation (costimulation), not anergy
Front
Oxygen-dependent killing by phagocytes is mediated by which agents?
Back
Reactive oxygen intermediates (ROIs), nitric oxide (NO), and hypochlorous acid (HOCl)
Front
What is the role of myeloperoxidase in phagocyte killing?
Back
It is the enzyme that makes HOCl (not itself the reactive species)
Front
A hapten binding to a skin self-protein induces what reaction?
Back
Contact hypersensitivity / contact dermatitis
Front
Contact dermatitis (from a hapten-modified self-protein) is which hypersensitivity type?
Back
Type IV (delayed-type hypersensitivity, DTH)
Front
Which cells mediate contact dermatitis (Type IV / DTH)?
Back
Th1 cells and macrophages
Front
Is hapten-induced contact dermatitis an IgE (Type I) reaction?
Back
No - it is Type IV (cell-mediated)
Front
What antibody causes hemolytic disease of the newborn (HDN)?
Back
Incomplete (IgG) anti-D antibodies
Front
In HDN, what is the maternal Rh status?
Back
Rh-negative (and sensitized)
Front
In HDN, what is the fetal Rh status of the destroyed RBCs?
Back
Rh-positive
Front
Why can the maternal anti-D antibody reach the fetus in HDN?
Back
It is IgG, the only class that crosses the placenta
Front
Must the Rh-negative mother be sensitized for HDN to occur?
Back
Yes - she must be previously sensitized to Rh-positive RBCs
Front
Which infectious disease has been eradicated by vaccination?
Back
Smallpox
Front
Has polio been eradicated by vaccination?
Back
No - not yet eradicated
Front
What is the name of an agent that augments/enhances a vaccine?
Back
An adjuvant
Front
What does an adjuvant do in a vaccine?
Back
Augments and prolongs antigen presentation and recruits APCs
Front
Give an example of a vaccine adjuvant.
Back
Alum (aluminum salts)
Front
What is the defining feature of an antigen-presenting cell (APC)?
Back
Expression of MHC class II
Front
Which cells are the professional APCs?
Back
B cells, macrophages, and dendritic cells
Front
Why is MHC class I not the discriminating marker for APCs?
Back
MHC I is on all nucleated cells, so it does not distinguish APCs
Front
How is information about an antigen's pathogenicity transmitted to T cells?
Back
By costimulatory molecules (B7 / CD80/86) on APCs
Front
What induces APCs to express costimulatory molecules?
Back
TLR (PRR) stimulation by PAMPs, signaling danger
Front
Does the antigen itself (or MHC alone) signal pathogenicity to T cells?
Back
No - costimulatory molecules do, after PRR/danger sensing
Front
What receptor does a naive T cell fail to express that an effector T cell expresses?
Back
The high-affinity IL-2 receptor (IL-2R / CD25)
Front
What is the alternative name for IL-2R alpha chain?
Back
CD25
Front
What is the function of IL-2R / CD25 once expressed on an activated T cell?
Back
Drives clonal expansion
Front
Degradation in proteasomes is characteristic of which class of antigens?
Back
Intrinsic (endogenous) antigens
Front
Proteasomal peptides are loaded onto which MHC class?
Back
MHC class I
Front
Proteasome → MHC I presentation primes which T cell subset?
Back
CD8 T cells
Front
Which processing route do extrinsic/exogenous antigens use?
Back
Endosome → MHC class II → CD4 T cells
Front
Which IgG subclass cannot activate (fix) complement?
Back
IgG4
Front
Which IgG subclasses are the strongest complement fixers?
Back
IgG3 > IgG1
Front
Which complement pathways are strictly innate (antibody-independent)?
Back
The alternative and lectin pathways
Front
Why is the classical complement pathway not strictly innate?
Back
It requires antibody to activate
Front
What does innate immunity recognize?
Back
PAMPs (pathogen-associated molecular patterns) and DAMPs (damage-associated molecular patterns)
Front
Does innate immunity recognize only PAMPs?
Back
No - it recognizes both PAMPs and DAMPs
Front
What causes the vasodilation seen in acute inflammation?
Back
Mast-cell degranulation
Front
Which mediator from mast cells drives early vasodilation in inflammation?
Back
Histamine (and other vasoactive mediators)
Front
Which vaccine type is most effective at inducing a cellular (cell-mediated) immune response?
Back
Live-attenuated vaccine
Front
Why do live-attenuated vaccines give strong cellular immunity?
Back
Their replication drives strong CD8/Th1 responses
Front
Which arm of immunity do killed/inactivated vaccines favor?
Back
Humoral immunity
Front
Activation of CD8 T cells against a weakly pathogenic antigen is supported by which cell?
Back
CD4-positive Th1 cells
Front
How do CD4 Th1 cells help activate CD8 T cells against weak antigens?
Back
Via cytokines / dendritic cell licensing
Front
Which immunoglobulin class is produced by B1 lymphocytes?
Back
IgM
Front
What are the IgM antibodies made by B1 cells described as?
Back
Polyreactive natural antibodies, secreted without T-cell help
Front
Which isotype dominates the early primary immune response?
Back
IgM
Front
Are gingivitis and periodontitis the same disease?
Back
No - gingivitis precedes and differs from periodontitis
Front
What distinguishes periodontitis from gingivitis?
Back
Periodontitis involves alveolar bone loss
Front
What is the keystone pathogen of periodontitis?
Back
Porphyromonas gingivalis
Front
What characterizes severe periodontal disease?
Back
Alveolar bone loss
Front
Which arm(s) of immunity do mRNA COVID-19 vaccines stimulate?
Back
Both humoral and cellular
Front
Why do mRNA COVID-19 vaccines stimulate cellular immunity?
Back
Spike is expressed intracellularly → MHC I → CD8/cellular response
Front
Do mRNA COVID-19 vaccines produce only a humoral response?
Back
No - they produce both humoral and cellular responses
Front
Braces, crowns, and dental fillings may induce which type of hypersensitivity?
Back
Delayed-type hypersensitivity (Type IV)
Front
How do dental metals/materials trigger Type IV hypersensitivity?
Back
They act as haptens modifying self-proteins, triggering Th1 + macrophage contact reactions
Front
What is the best method to define a cell's phenotype (size, granularity, CD markers)?
Back
Flow cytometry (FACS)
Front
In flow cytometry, what does forward scatter measure?
Back
Cell size
Front
In flow cytometry, what does side scatter measure?
Back
Granularity
Front
In flow cytometry, how are CD markers detected?
Back
Fluorescent (labeled) antibodies
Front
What defect does the NBT (nitro-blue tetrazolium) test screen for?
Back
Defective intracellular oxidative killing by phagocytes
Front
A positive (defective) NBT test indicates which disease?
Back
Chronic Granulomatous Disease (CGD)
Front
Why does NBT fail to be reduced in CGD?
Back
A failed NADPH-oxidase respiratory burst cannot reduce it
Front
What immunological event does cross-presentation allow?
Back
Activation of a CD8+ T cell by an endocytosed (exogenous) antigen
Front
In cross-presentation, exogenous antigen is routed onto which MHC class?
Back
MHC class I
Front
Which cells perform cross-presentation?
Back
Specialized dendritic cells
Front
Which cells does HIV infect?
Back
CD4+ T-helper cells plus monocytes/macrophages
Front
What is HIV's primary receptor?
Back
CD4
Front
What are HIV's co-receptors?
Back
CXCR4 and CCR5
Front
Why are monocytes/macrophages HIV targets and reservoirs?
Back
They express CD4
Front
Serum sickness is which type of hypersensitivity?
Back
Type III (immune-complex-mediated)
Front
What is the underlying mechanism of Type III hypersensitivity?
Back
Circulating antigen-antibody complexes deposit in tissues
Front
In Type III hypersensitivity, which cells arrive first?
Back
Neutrophils
Front
What mediates the tissue damage in Type III hypersensitivity?
Back
Complement
Front
Besides serum sickness, name another Type III reaction.
Back
The Arthus reaction
Front
Delayed-type hypersensitivity (DTH) is which type?
Back
Type IV
Front
Which cells mediate Type IV (DTH) hypersensitivity?
Back
Th1 cells and macrophages
Front
Is antibody involved in Type IV (DTH) hypersensitivity?
Back
No — it is cell-mediated
Front
At what time does a DTH reaction peak?
Back
48-72 hours
Front
What is the correct order of steps in a Western blot?
Back
Electrophoresis (SDS-PAGE) -> transfer (blotting) -> immunodetection
Front
In a competitive ELISA, how does absorbance relate to antigen concentration?
Back
Inversely (absorbance is proportional to 1/antigen)
Front
Why is the competitive ELISA relationship inverse?
Back
More sample antigen competes off the labeled reagent, lowering signal
Front
In a sandwich or indirect ELISA, how does absorbance relate to antigen concentration?
Back
Directly (more antigen = higher signal)
Front
Which molecule does a naive T cell fail to express that an effector T cell expresses?
Back
IL-2 receptor (CD25)
Front
When does a T cell acquire the high-affinity IL-2 receptor (CD25)?
Back
Upon activation
Front
Which complement pathways are strictly innate (antibody-independent)?
Back
Alternative and lectin pathways
Front
Which complement pathway requires antibody?
Back
The classical pathway
Front
Which IgG subclass cannot fix complement?
Back
IgG4
Front
Oxygen-dependent killing by phagocytes is mediated by which agents?
Back
Reactive oxygen intermediates (ROIs), nitric oxide (NO), and hypochlorous acid (HOCl)
Front
What does the NBT (or DHR) test screen for?
Back
Defective intracellular oxidative (respiratory-burst) killing by phagocytes
Front
Which disease does an abnormal NBT/DHR test diagnose?
Back
Chronic Granulomatous Disease (CGD)
Front
What is the best method to define a cell's phenotype (size, granularity, CD markers)?
Back
Flow cytometry (FACS)
Front
In flow cytometry, what does forward scatter (FSC) measure?
Back
Cell size
Front
In flow cytometry, what does side scatter (SSC) measure?
Back
Cell granularity
Front
What separation technique does MACS use?
Back
Magnetic-bead separation
Front
In MACS, what does negative selection isolate?
Back
The untouched target cells (unwanted cells are labeled and removed)
Front
What is Ficoll used for?
Back
Density-gradient isolation of PBMCs (peripheral blood mononuclear cells)
Front
In a sandwich or indirect ELISA, how does absorbance relate to antigen concentration?
Back
Directly proportional (absorbance increases with antigen)
Front
In a competitive ELISA, how does absorbance relate to antigen concentration?
Back
Inversely proportional (absorbance decreases as antigen increases)
Front
What is the best test for measuring anti-bacterial serum antibody level?
Back
ELISA
Front
What is the correct order of steps in a Western blot?
Back
Electrophoresis -> transfer -> immunodetection
Front
What does the indirect Coombs test detect?
Back
Maternal anti-Rh antibody in the serum (pregnancy screen)
Front
What does the direct Coombs test detect?
Back
Antibody already bound on the RBC surface
Front
Which vaccine types can be safely given to immunodeficient patients?
Back
Killed/inactivated and subunit vaccines
Front
Can live-attenuated vaccines be given to immunodeficient patients?
Back
No - they are contraindicated
Front
In which patient groups is live-attenuated vaccine contraindicated?
Back
Immunodeficiency, pregnancy, and HIV
Front
Which vaccine type gives the best cell-mediated (cellular) immune response?
Back
Live-attenuated vaccines
Front
Which infectious disease has been eradicated by vaccination?
Back
Smallpox
Front
Which arm(s) of immunity do mRNA COVID-19 vaccines stimulate?
Back
Both humoral and cellular
Front
What does an adjuvant do in a vaccine?
Back
Augments and prolongs the antigen's effect / recruits APCs, boosting the immune response
Front
Give an example of a still-used vaccine adjuvant.
Back
Alum
Front
Which vaccines are the oral polio vaccines?
Back
Sabin (oral) and Koprowski
Front
Is BCG an attenuated vaccine?
Back
Yes, BCG is attenuated
Front
Which vaccines are NOT attenuated (whole-cell pertussis, rabies, HepB candidates)?
Back
Pertussis (whole-cell), rabies, and HepB
Front
Which immunoglobulin class do B1 lymphocytes produce?
Back
IgM (natural antibodies)
Front
Which immunoglobulin class crosses the placenta?
Back
IgG only
Front
Which isotype dominates the early primary immune response?
Back
IgM
Front
Are gingivitis and periodontitis the same condition?
Back
No - gingivitis precedes and differs from periodontitis
Front
What is the keystone pathogen of periodontitis?
Back
Porphyromonas gingivalis
Front
What characterizes severe periodontitis?
Back
Alveolar bone loss
Front
What antibody causes hemolytic disease of the newborn (HDN)?
Back
Incomplete (IgG) anti-D antibody
Front
In HDN, what is the Rh status of the affected mother?
Back
Rh-negative and sensitized
Front
In HDN, what is the Rh status of the affected fetal RBCs that are destroyed?
Back
Rh-positive
Front
Why can the anti-D antibody in HDN reach the fetus?
Back
It is IgG, which crosses the placenta
Front
Which immunoglobulin carries the secretory component?
Back
Secretory IgA
Front
For a 2026 sitting, which IgA subclass is the examiner-preferred key for the secretory component?
Back
IgA2
Front
Which statement about innate immunity recognition is correct?
Back
It recognizes both PAMPs and DAMPs
Front
Does innate immunity have antigen-specific memory?
Back
No (it recognizes conserved patterns, not specific antigens)
Front
What does PAMP stand for?
Back
Pathogen-associated molecular pattern
Front
Give examples of PAMPs.
Back
LPS, peptidoglycan, flagellin, dsRNA
Front
Are PAMPs unique to a single pathogen or shared across microbes?
Back
Shared across many different microbes (conserved structures)
Front
What does DAMP stand for?
Back
Damage/danger-associated molecular pattern
Front
Where do DAMPs come from?
Back
Endogenous molecules released by stressed/dying host cells
Front
How does the diversity of PRRs compare to the TCR?
Back
PRRs recognize a limited germline-encoded set; the TCR has far greater clonal diversity
Front
Are PRRs germline-encoded or clonally rearranged?
Back
Germline-encoded
Front
What is the keyed exam fact about TLR4 and LPS?
Back
LPS ligation of TLR4 activates APCs
Front
Which TLR senses LPS?
Back
TLR4
Front
On which type of bacteria is LPS found?
Back
Gram-negative bacteria
Front
State the TLR4 signaling chain (LPS to APC).
Back
LPS → TLR4 → APC activation
Front
Which inflammasome activates IL-1β?
Back
The NLRP3 inflammasome
Front
What does the NLRP3 inflammasome do to pro-IL-1β?
Back
Processes it into active IL-1β
Front
Which two cytokines drive the hepatic acute-phase protein response?
Back
IL-1 and IL-6
Front
Which cytokine pairs are distractors for the acute-phase response?
Back
IL-12+IFN-γ, IL-4+IL-5, TGF-β+IL-10
Front
In the single-answer phrasing, which ONE cytokine is keyed for acute-phase protein release?
Back
IL-6
Front
What causes the vasodilation seen in acute inflammation?
Back
Mast-cell degranulation (releasing histamine/vasoactive mediators)
Front
Which leukocyte dominates the site during the first ~6 hours of acute inflammation?
Back
Neutrophils
Front
Which cells arrive later than neutrophils in acute inflammation?
Back
Macrophages/monocytes
Front
List the oxygen-dependent (oxidative) killing products of phagocytes.
Back
Reactive oxygen intermediates (ROIs), nitric oxide (NO), hypochlorous acid (HOCl)
Front
In the oxidative-killing item, why is myeloperoxidase a distractor?
Back
It is the enzyme that makes HOCl, not a reactive species itself
Front
Which enzyme generates the superoxide of the respiratory burst in phagocytes?
Back
NADPH oxidase
Front
What does the NBT (nitro-blue tetrazolium) / DHR test screen for?
Back
Defective intracellular oxidative (respiratory-burst) killing by phagocytes
Front
An abnormal NBT/DHR test points to which disease?
Back
Chronic Granulomatous Disease (CGD)
Front
What is the underlying defect in Chronic Granulomatous Disease?
Back
Defective NADPH oxidase → failed respiratory burst
Front
Why does NBT fail to be reduced in CGD?
Back
No reactive oxygen species are generated
Front
Which CD marker is found on ALL T cells?
Back
CD3
Front
What is CD3 part of?
Back
The TCR signaling complex
Front
Which CD marker defines helper T cells?
Back
CD4
Front
On which non-T cells is CD4 also expressed?
Back
Monocytes/macrophages
Front
CD4 is the primary receptor for which virus?
Back
HIV
Front
What are HIV's co-receptors?
Back
CXCR4 and CCR5
Front
Which CD marker defines cytotoxic T cells?
Back
CD8
Front
Cytotoxic (CD8) T cells recognize peptide presented on which MHC class?
Back
MHC class I
Front
Which CD marker is the monocyte/macrophage LPS co-receptor?
Back
CD14
Front
CD14 works with which TLR in LPS sensing?
Back
TLR4
Front
Which CD marker defines B lymphocytes?
Back
CD19
Front
Which CD marker is the defining phenotypic marker of NK cells?
Back
CD56
Front
Which receptor (not CD56) mediates ADCC on NK cells?
Back
CD16 (FcγRIII)
Front
Which CD marker is found on all T cells?
Back
CD3
Front
Which CD marker defines helper T cells?
Back
CD4
Front
Besides helper T cells, which cells also express CD4?
Back
Monocytes/macrophages
Front
CD4 is the primary receptor for which virus?
Back
HIV
Front
Which CD marker defines cytotoxic T cells?
Back
CD8
Front
Which CD marker is the monocyte/macrophage LPS co-receptor?
Back
CD14
Front
Which CD marker defines B lymphocytes?
Back
CD19
Front
Which CD marker defines NK cells?
Back
CD56
Front
Which receptor on NK cells mediates ADCC?
Back
CD16 (FcγRIII)
Front
Name a principal immune function of the macrophage besides phagocytosis.
Back
Antigen presentation
Front
What is efferocytosis, a macrophage function?
Back
Clearance of apoptotic cells
Front
Which professional APC links innate and adaptive immunity via antigen presentation?
Back
The macrophage
Front
Macrophages present antigen on which MHC class?
Back
MHC class II
Front
Name the tissue macrophage of the liver.
Back
Kupffer cell
Front
Name the tissue macrophage of the CNS/brain.
Back
Microglia
Front
Name the bone macrophage-lineage cell that resorbs bone.
Back
Osteoclast
Front
Which cells mediate alveolar bone loss in periodontitis?
Back
Osteoclasts
Front
Which complement pathways are strictly innate (antibody-independent)?
Back
Alternative and lectin pathways
Front
Why is the classical complement pathway not strictly innate?
Back
It requires antibody
Front
What triggers the classical complement pathway?
Back
Antigen-antibody complexes (antibody)
Front
With which component does the classical complement pathway begin?
Back
C1
Front
After C1, which components continue the classical pathway?
Back
C4 then C2
Front
C4 and C2 of the classical pathway form which convertase?
Back
The C3 convertase
Front
Which complement components form the membrane attack complex (MAC)?
Back
C5b-C9
Front
What does the membrane attack complex (C5b-9) do?
Back
Forms a lytic pore in the target membrane
Front
The MAC is the terminal pathway common to how many complement routes?
Back
All three
Front
Which IgG subclass cannot fix the classical complement pathway?
Back
IgG4
Front
Besides IgG4, which immunoglobulin class does not fix the classical pathway?
Back
IgA
Front
Which are the primary (central) lymphoid organs?
Back
Thymus and bone marrow
Front
What defines a primary lymphoid organ?
Back
Where lymphocytes develop/mature
Front
Where do T cells mature?
Back
The thymus
Front
Where do B lymphocytes mature?
Back
The bone marrow
Front
Which adhesion molecules guide lymphocyte homing/extravasation into tissues?
Back
Selectins (via rolling)
Front
Where do dendritic cells primarily present antigen to T cells?
Back
The lymph nodes
Front
Lymph nodes are which category of lymphoid organ?
Back
Secondary lymphoid organs
Front
Which cells directly kill virus-infected cells without prior sensitization?
Back
NK (natural killer) cells
Front
Which cytotoxic molecules do NK cells share with CD8 CTLs?
Back
Perforin and granzyme
Front
Through which receptor do NK cells mediate ADCC?
Back
CD16 (FcγRIII)
Front
In ADCC, what does the NK cell CD16 bind?
Back
The Fc of IgG coating the target
Front
Which cells provide protection against intracellular pathogens?
Back
T cells and NK cells
Front
What type of inflammatory process drives alveolar bone loss in periodontitis?
Back
A chronic, cytokine-driven process activating osteoclasts
Front
Which mediators drive osteoclast activation in periodontitis?
Back
IL-1, TNF, IL-6, RANKL
Front
On 'periodontitis statements except,' which statement is false?
Back
That gingivitis and periodontitis are the same
Front
Which condition precedes periodontitis?
Back
Gingivitis
Front
What is the keystone pathogen of periodontitis?
Back
P. gingivalis
Front
Severe periodontitis is characterized by what tissue change?
Back
Alveolar bone loss
Front
What is the best laboratory method to define a cell's phenotype (size, granularity, CD markers)?
Back
Flow cytometry (FACS)
Front
In flow cytometry, what does forward scatter (FSC) measure?
Back
Cell size
Front
In flow cytometry, what does side scatter (SSC) measure?
Back
Granularity
Front
In flow cytometry, how is CD-marker expression detected?
Back
Fluorescent antibodies
Front
Which region of the antibody molecule binds antigen?
Back
The Fab region (fragment antigen-binding)
Front
Which antibody region mediates complement fixation, placental transfer, ADCC, and cytophilic binding?
Back
The Fc region (fragment crystallizable)
Front
The Fc region is the antibody's effector tail made of which structural part?
Back
The constant region
Front
The constant region of the immunoglobulin heavy chain dictates the antibody's what?
Back
Its isotype (antibody class)
Front
Which antibody property does the heavy-chain constant region determine: isotype, idiotype, or allotype?
Back
Isotype
Front
Which immunoglobulin classes make up the isotypes?
Back
IgG, IgA, IgM, IgE, IgD
Front
What does an antibody's idiotype refer to?
Back
Its variable-region/CDR antigen specificity
Front
What does an antibody's allotype refer to?
Back
An allelic (genetic) variant
Front
What determines antigen-recognition specificity in the variable region of an antibody?
Back
The CDRs (complementarity-determining regions / hypervariable loops)
Front
What part of the antibody do the CDRs form?
Back
The antigen-binding paratope
Front
Another name for the CDRs (complementarity-determining regions)?
Back
Hypervariable loops
Front
What is the function of immunoglobulins (antibodies) in host defense?
Back
They tag antigens for destruction and removal
Front
Antibodies tag antigens, but which components actually do the killing?
Back
Complement, phagocytes, and NK cells (ADCC)
Front
Which single immunoglobulin class crosses the placenta?
Back
IgG only
Front
Placental transfer of IgG is mediated by which antibody region?
Back
The Fc region
Front
What does IgG placental transfer provide to the neonate?
Back
Passive neonatal immunity
Front
What term describes the Fc-mediated ability of antibody to bind immune-cell surfaces (mast cells, macrophages, NK)?
Back
Cytophilic binding
Front
In cytophilic binding, which antibody region adheres to Fc receptors on cells?
Back
The Fc region
Front
In ADCC against a virus-infected cell, what does the NK cell recognize to trigger killing?
Back
IgG bound to viral capsid protein on the target cell's plasma membrane
Front
Which NK receptor binds the Fc of surface-bound IgG during ADCC?
Back
CD16 (FcγRIII)
Front
Secretory IgA protects mucosal surfaces primarily by which mechanism?
Back
By preventing microbial adherence to the mucosa
Front
Does secretory IgA activate complement?
Back
No
Front
What is the molecular form of secretory IgA at mucosal surfaces?
Back
A dimer joined by a J chain plus a secretory component
Front
When is the secretory component added to IgA?
Back
During epithelial transcytosis
Front
What does the secretory component protect IgA from in secretions?
Back
Proteolysis
Front
Which immunoglobulin carries the secretory component and dominates oral-cavity mucosal surveillance?
Back
Secretory IgA
Front
If forced to a subclass, which IgA subclass carries the secretory component (examiner-preferred)?
Back
IgA2
Front
Which immunoglobulin binds strongly to mast cells and mediates Type I hypersensitivity?
Back
IgE
Front
IgE binds which high-affinity receptor on mast cells/basophils?
Back
FcεRI
Front
Does IgE fix (activate) complement?
Back
No
Front
Is IgE abundant in saliva?
Back
No
Front
What is the defining feature of an antigen-presenting cell (APC)?
Back
Expression of MHC class II
Front
Professional APCs present exogenous peptide on MHC II to which T cells?
Back
CD4 T cells
Front
On which cell types is MHC class II found?
Back
B cells, dendritic cells (APCs), and macrophages
Front
Which cells express MHC class I?
Back
All nucleated cells
Front
MHC class I presents endogenous peptide to which T cells?
Back
CD8 T cells
Front
What form of antigen does the T-cell receptor (TCR) recognize?
Back
A linear antigenic peptide in the MHC groove
Front
What form of antigen does the B-cell receptor (BCR) recognize?
Back
Soluble, native (conformational) antigen directly
Front
Are T cells MHC-restricted in their antigen recognition?
Back
Yes
Front
Antigens degraded in the proteasome belong to which processing pathway?
Back
Intrinsic (endogenous) antigens
Front
Proteasome-degraded (endogenous) peptides are loaded onto which MHC class?
Back
MHC class I
Front
Trace the endogenous antigen-processing pathway from degradation to T-cell subset.
Back
Proteasome → endogenous antigen → MHC class I → CD8 T cell
Front
Trace the exogenous antigen-processing pathway from degradation to T-cell subset.
Back
Endosome/lysosome → exogenous antigen → MHC class II → CD4 T cell
Front
What does cross-presentation allow?
Back
Activation of a CD8 T cell by endocytosed (exogenous) antigen
Front
In cross-presentation, exogenous antigen is routed onto which MHC class?
Back
MHC class I
Front
In a secondary CD8 cytotoxic response, which cell presents the antigen?
Back
An MHC-I-expressing somatic (any nucleated) cell, not a professional APC
Front
Which immunoglobulin classes do mature, pre-class-switch (naïve) B cells co-express on their surface?
Back
IgM and IgD
Front
Which immunoglobulin classes do naive (pre-class-switch) B cells co-express on their surface?
Back
IgM and IgD
Front
Which immunoglobulin class is produced by B1 lymphocytes?
Back
IgM (natural antibodies)
Front
What kind of IgM do B1 cells secrete?
Back
Low-affinity, polyreactive IgM with little class switching
Front
Which immunoglobulin isotype dominates the early primary antibody response?
Back
IgM
Front
Which isotypes does class switching produce in the secondary response?
Back
IgG, IgA, and IgE
Front
Which enzymes mediate V(D)J recombination?
Back
RAG1 and RAG2 (recombination-activating genes)
Front
What does V(D)J recombination assemble?
Back
The variable region, creating pre-antigen receptor diversity
Front
By what process does antibody affinity increase during the secondary response?
Back
Somatic hypermutation of variable-region genes in germinal centers, then selection
Front
Where does somatic hypermutation occur?
Back
In germinal centers
Front
Does affinity maturation use RAG/V(D)J recombination?
Back
No
Front
Which IgG subclass is unable to fix complement?
Back
IgG4
Front
Which IgG subclasses are the strong classical-pathway complement fixers?
Back
IgG3 and IgG1 (IgG3 strongest)
Front
Rank IgG1 vs IgG3 for complement-fixing strength.
Back
IgG3 > IgG1
Front
Which IgG subclass is the non-fixer of complement?
Back
IgG4
Front
What does an antibody titer refer to?
Back
The highest dilution of serum that still gives a positive result
Front
Define antibody avidity in terms of affinity and valency.
Back
Avidity = affinity × valency (total binding strength)
Front
What does affinity measure?
Back
Single-site binding strength
Front
Which immunoglobulin is the classic example of high avidity?
Back
IgM
Front
Which helper cell supports CD8 T-cell activation against a weakly-pathogenic antigen?
Back
CD4+ Th1 cells
Front
How do Th1 cells help prime CD8 against low-danger antigens?
Back
They license the APC and provide help (IL-2, CD40L)
Front
What transmits information about an antigen's pathogenicity to T cells?
Back
Costimulatory molecules expressed by APCs after TLR stimulation
Front
Which costimulatory molecules constitute signal 2 to T cells?
Back
B7 / CD80-86
Front
What upregulates B7/CD80-86 on APCs?
Back
TLR sensing of PAMPs
Front
In an antigen-antibody precipitation reaction, what is the physical state of the antigen?
Back
Soluble antigen
Front
What does soluble antigen form when it reacts with antibody in precipitation?
Back
An insoluble lattice that precipitates out of solution
Front
In an agglutination reaction, what is the physical state of the antigen?
Back
Particulate antigen
Front
What happens to particulate antigen when antibody crosslinks it?
Back
It clumps (agglutinates)
Front
Discriminate precipitation vs agglutination by antigen type.
Back
Precipitation = soluble antigen lattice; agglutination = particulate antigen clumps
Front
Blood typing (ABO/Rh) is an example of which antigen-antibody reaction?
Back
Agglutination
Front
Why is blood typing agglutination rather than precipitation?
Back
RBCs are particulate antigens
Front
The latex syphilis test is an example of which antigen-antibody reaction?
Back
Agglutination
Front
Measuring a bacterial titer (clumping of whole bacteria) is which reaction type?
Back
Agglutination
Front
Why is a bacterial titer an agglutination reaction?
Back
Whole bacteria are particulate antigens
Front
What does a high bacterial agglutination titer reflect?
Back
A secondary (anamnestic) antibody response
Front
Name the three classic lab examples of agglutination reactions.
Back
Blood typing, latex syphilis test, and bacterial titer
Front
Which laboratory technique is used to quantify antigen or antibody?
Back
Radial immunodiffusion
Front
In radial immunodiffusion, what is the ring diameter proportional to?
Back
Antigen concentration
Front
What is the primary function of radial immunodiffusion?
Back
To quantify antigen or antibody concentration
Front
What type of method is radial immunodiffusion?
Back
A precipitation-in-gel method
Front
What two principles does immunoelectrophoresis combine?
Back
Electrophoretic separation of antigens followed by immunodiffusion
Front
In immunoelectrophoresis, on what basis are antigens electrophoretically separated?
Back
By charge and size
Front
What forms where separated antigen meets specific antibody in immunoelectrophoresis?
Back
Precipitation arcs
Front
How is antibody titer defined?
Back
The highest dilution of serum that still gives a positive result
Front
A high bacterial agglutination titer indicates which type of immune response?
Back
A secondary (anamnestic) response
Front
Why does a high agglutination titer indicate a secondary response?
Back
High antibody levels reflect prior sensitization/memory
Front
Both precipitation and agglutination depend on which fundamental antibody property?
Back
Antibody bivalency/multivalency enabling crosslinking of antigen
Front
With soluble antigen, antibody crosslinking produces what?
Back
A lattice (precipitation)
Front
With particulate antigen, antibody crosslinking produces what?
Back
Clumps (agglutination)
Front
In a secondary CD8+ cytotoxic response, the antigen is presented on which type of cell?
Back
An MHC class I-expressing somatic (any nucleated) cell, not a professional APC
Front
Which MHC class restricts the cytotoxic CD8+ T-cell secondary effector response?
Back
MHC class I
Front
Which cells express MHC class I (presenting endogenous peptide to CD8 effectors)?
Back
All nucleated (somatic) cells
Front
Why is the secondary CD8 killing target a somatic cell rather than a professional APC?
Back
Effector CTLs recognize endogenous peptide on MHC-I of the infected somatic target and kill it directly
Front
Does the secondary CD8 kill require a professional MHC-II APC?
Back
No
Front
ADCC against a virus-infected cell is induced by which specifically bound molecule?
Back
IgG bound to viral capsid protein on the target cell's plasma membrane
Front
In ADCC, which receptor on the NK cell engages the Fc of the surface-bound IgG?
Back
CD16 (FcγRIII)
Front
In ADCC of a virus-infected cell, where must the antibody-bound antigen be located?
Back
On the target cell's plasma membrane (surface)
Front
Why can't intracellular/cytoplasmic antigen trigger ADCC?
Back
It is inaccessible to antibody
Front
Which antibody isotype mediates ADCC against a virus-infected cell?
Back
IgG
Front
Through which effector receptor does the NK cell engage IgG in ADCC?
Back
CD16 (FcγRIII)
Front
Name the two distinct cytotoxic killing routes used by CTLs and NK cells.
Back
Perforin/granzyme (granule-exocytosis) pathway and the FasL-Fas death-receptor pathway
Front
Besides FasL-Fas, which other receptor pair acts in the death-receptor killing route?
Back
TNF-TNFR
Front
Both CTL/NK killing pathways converge on what fate for the target cell?
Back
Apoptosis
Front
What is the role of perforin in CTL/NK killing?
Back
It polymerizes to form pores in the target membrane
Front
What is the role of granzymes in CTL/NK killing?
Back
Serine proteases that enter via perforin pores and trigger the caspase apoptosis cascade
Front
The perforin/granzyme killing route is also called what?
Back
The granule-exocytosis (granule-dependent) route
Front
Which CTL killing pathway is receptor-dependent rather than granule-dependent?
Back
The FasL-Fas (CD95) death-receptor pathway
Front
In the FasL-Fas pathway, what does CTL FasL engage on the target?
Back
Fas (CD95)
Front
What does Fas engagement on the target trigger?
Back
The death-receptor caspase cascade leading to apoptosis
Front
Do NK cells and CD8+ CTLs share cytotoxic machinery?
Back
Yes — both use perforin/granzyme and FasL-Fas
Front
How does NK recognition differ from CTL recognition?
Back
NK killing is MHC-I-independent (missing-self); CTL killing is MHC-I-restricted/antigen-specific
Front
Which lymphocyte kills virally-infected cells directly without prior sensitization or MHC restriction?
Back
NK cells
Front
By what recognition mechanism do NK cells target cells?
Back
Missing-self recognition (innate)
Front
DTH (delayed-type hypersensitivity) is classified as which hypersensitivity type?
Back
Type IV
Front
DTH is mediated by antibody or by cells?
Back
Cell-mediated (T-cell), not antibody
Front
What is the time course of a delayed-type hypersensitivity reaction?
Back
Delayed, 24-72 hours
Front
Which cells mediate DTH / Type IV hypersensitivity?
Back
Th1 cells + macrophages
Front
How do Th1 cells recruit and activate macrophages in DTH?
Back
By releasing IFN-γ
Front
What is the molecular trigger of allergic contact dermatitis?
Back
A hapten binding a skin self-protein (carrier) to form a complete immunogen
Front
Allergic contact dermatitis is which hypersensitivity type and T-cell subset?
Back
Type IV (DTH), Th1-mediated
Front
Metal braces, crowns, and dental fillings may induce which immune reaction?
Back
Delayed-type hypersensitivity (DTH / Type IV)
Front
How do metal ions in dental materials trigger DTH?
Back
They act as haptens binding oral/skin self-proteins, driving a Th1 + macrophage contact reaction
Front
Contact dermatitis is which hypersensitivity type?
Back
Type IV (DTH)
Front
Contact dermatitis is mediated by which T helper subset?
Back
Th1 (with macrophages as effectors)
Front
Which cytokines drive naïve CD4+ T-cell differentiation toward Th1?
Back
IL-12 (from APCs/macrophages) and IFN-γ
Front
Which transcription factor commits CD4+ T cells to the Th1 lineage?
Back
T-bet
Front
Th1 differentiation supports which type of immunity?
Back
Cell-mediated immunity
Front
Which cytokine drives naïve CD4+ T-cell differentiation toward Th2?
Back
IL-4
Front
Which transcription factor commits CD4+ T cells to the Th2 lineage?
Back
GATA3
Front
Th2 differentiation supports which type of responses?
Back
Humoral/allergic responses
Front
Suppression of Th1 by Th2 is mediated by which cytokine?
Back
IL-10
Front
What is the cellular source of the IL-10 that suppresses Th1?
Back
Th2 cells
Front
Which Th1 cytokine cross-regulates (suppresses) Th2?
Back
IFN-gamma
Front
Which Th2-derived cytokine suppresses Th1?
Back
IL-10
Front
What is the result of the mutual Th1/Th2 cross-regulation called?
Back
Immune deviation
Front
Is CD8+ cytotoxic killing of virally-infected cells a Th1 or Th2 function?
Back
Th1 (cell-mediated)
Front
Which arm of immunity does a Th2 response drive?
Back
Humoral / IgE / eosinophil responses
Front
Which CD4+ T-cell subset recruits and activates macrophages (phagocytes)?
Back
Th1
Front
Which cytokines does Th1 secrete to recruit/activate macrophages?
Back
IFN-gamma and IL-2
Front
What is the principal macrophage-activating signal from Th1 cells?
Back
IFN-gamma
Front
What does IFN-gamma do to macrophages?
Back
Activates them, enhancing microbicidal/oxidative killing
Front
What is the primary autocrine T-cell growth/proliferation cytokine from activated Th1 cells?
Back
IL-2
Front
What does IL-2 do for T cells?
Back
Drives clonal proliferation of activated T cells
Front
Which receptor marks activated/effector T cells (not naive T cells)?
Back
IL-2R (CD25)
Front
Activation of a CD8+ T cell against a weakly-pathogenic antigen is supported by which helper cell?
Back
CD4+ Th1
Front
Why does CD8 activation by a weak antigen require Th1 help?
Back
Weak antigens cannot fully license the APC alone
Front
What does CD4+ Th1 provide to enable CD8 priming against weak antigens?
Back
IL-2 and CD40L-mediated APC licensing/costimulation
Front
Which Th subset orchestrates immunity to intracellular pathogens?
Back
Th1
Front
What cytokines drive Th1 differentiation?
Back
IL-12 and IFN-gamma
Front
How does Th1 fight intracellular microbes?
Back
Activates macrophages and supports CD8 CTLs
Front
Which Th subset handles extracellular/parasitic/allergic responses?
Back
Th2
Front
How does NK cell killing recognize targets (relative to MHC-I)?
Back
MHC-I-independent 'missing-self' (kills cells that down-regulate MHC-I)
Front
How does CD8 CTL killing recognize targets (relative to MHC-I)?
Back
MHC-I-restricted, antigen-specific (kills cells presenting peptide on MHC-I)
Front
What effector machinery do NK cells and CD8 CTLs share?
Back
Perforin/granzyme and Fas
Front
Serum sickness and Arthus reactions are which hypersensitivity type?
Back
Type III (immune-complex)
Front
Delayed-type hypersensitivity (DTH) is which hypersensitivity type?
Back
Type IV (cell-mediated)
Front
Which cells mediate Type IV DTH?
Back
Th1 + macrophages
Front
What are the four mechanisms of autotolerance (self-tolerance)?
Back
Clonal deletion, clonal anergy, active suppression (Tregs), sequestration of antigens
Front
Is 'immune paralysis' one of the four keyed autotolerance mechanisms?
Back
No
Front
Is 'exhaustion of memory cells/clones' one of the four keyed autotolerance mechanisms?
Back
No
Front
Is 'positive/negative selection' the keyed answer for the four mechanisms of autotolerance?
Back
No
Front
What does immunological paralysis refer to?
Back
Subliminal-threshold unresponsiveness
Front
Which tolerance mechanism is broken in atopic (allergic) individuals?
Back
Immunological facilitation
Front
How do Tregs enforce/support clonal anergy (molecular mechanism)?
Back
Their CTLA-4 (CD152) binds CD80/CD86 (B7) on the APC
Front
By binding B7, what does Treg CTLA-4 outcompete?
Back
CD28 costimulation
Front
What is the CD designation for CTLA-4?
Back
CD152
Front
Which APC ligands does Treg CTLA-4 (CD152) bind to enforce anergy?
Back
CD80 and CD86 (the B7 molecules)
Front
What is the CD designation for CTLA-4?
Back
CD152
Front
On the APC, which molecules does CTLA-4 (CD152) bind?
Back
CD80/86 (B7)
Front
What does Treg CTLA-4 (CD152) enforce by binding the APC?
Back
Clonal anergy
Front
Which ligands on the APC does Treg CTLA-4 bind to enforce anergy?
Back
CD80 and CD86 (the B7 molecules)
Front
What is the alternative name for the B7 molecules?
Back
CD80 and CD86
Front
Tregs support clonal anergy by binding what on the APC?
Back
CD80/86 (B7)
Front
Tregs bind CD80/86 on the APC using which of their molecules?
Back
CD152 (CTLA-4)
Front
What two-signal event defines clonal anergy at the T-cell level?
Back
Signal 1 (TCR-peptide/MHC) without signal 2 (costimulation)
Front
What provides signal 2 (costimulation) for T-cell activation?
Back
CD28 binding CD80/86
Front
A naive T cell gets signal 1 but no costimulation - what is the outcome?
Back
Clonal anergy (functional unresponsiveness)
Front
Where does central tolerance occur?
Back
Primary lymphoid organs (thymus for T cells, bone marrow for B cells)
Front
How is central tolerance generated for T cells?
Back
Negative selection in the thymus
Front
In thymic negative selection, which T-cell clones are deleted?
Back
Those binding self-peptide on self-MHC too strongly
Front
Thymic negative selection is an example of which tolerance mechanism?
Back
Clonal deletion
Front
Where are self-reactive B cells deleted during central tolerance?
Back
Bone marrow
Front
Where is peripheral tolerance maintained?
Back
Outside the primary lymphoid organs
Front
Which clones does peripheral tolerance act on?
Back
Self-reactive clones that escaped central deletion
Front
Name the three mechanisms of peripheral tolerance.
Back
Clonal anergy, Treg active suppression, antigen sequestration
Front
Which tolerance mechanisms are central (thymus/bone marrow)?
Back
Clonal deletion (negative selection)
Front
Which tolerance mechanisms are peripheral?
Back
Clonal anergy, Treg active suppression, antigen sequestration
Front
What is the classic example of an immunologically privileged site?
Back
The testis
Front
What is an immunologically privileged site?
Back
An anatomical site sequestered from immune surveillance
Front
Which tolerance mechanism do privileged sites represent?
Back
Antigen sequestration
Front
Define immune ignorance as a tolerance state.
Back
Self-reactive lymphocytes coexist with self-antigen but do not respond
Front
Why does a clone ignore its self-antigen in immune ignorance?
Back
Antigen is below the concentration/location threshold to trigger activation
Front
Define immunological paralysis.
Back
Unresponsiveness produced by antigen at a subliminal threshold (e.g., very high/persistent dose)
Front
Is immunological paralysis the same as anergy?
Back
No - it is a distinct term
Front
Is immunological paralysis part of the four-part autotolerance list?
Back
No
Front
Is immunological paralysis a recognized peripheral-tolerance term?
Back
Yes (subliminal-threshold unresponsiveness)
Front
Define the anamnestic response.
Back
The faster, stronger immune response on re-exposure to a previously encountered antigen
Front
Which cells mediate the anamnestic response?
Back
Memory lymphocytes
Front
Name the two principal mechanisms by which autoimmunity arises.
Back
Molecular mimicry and release of sequestered antigens
Front
What is molecular mimicry as an autoimmunity mechanism?
Back
A microbial antigen resembles a self-antigen, so the anti-microbial response cross-reacts with self
Front
How does release of sequestered antigen cause autoimmunity?
Back
Trauma/infection exposes hidden self-antigens the immune system never became tolerant to
Front
Give examples of privileged sites whose antigen release can trigger autoimmunity.
Back
Testis, eye, brain
Front
Which immunoglobulin is associated with self-reactivity (natural autoantibodies)?
Back
Self-reactive IgM
Front
Active suppression as an autotolerance mechanism is carried out by which cells?
Back
Tregs (regulatory T cells)
Front
Where are self-reactive T cells deleted by clonal deletion?
Back
The thymus (negative selection)
Front
Where are self-reactive B cells deleted by clonal deletion?
Back
The bone marrow
Front
What is clonal deletion?
Back
Physical removal of self-reactive clones (central tolerance)
Front
In clonal deletion, what happens to the self-reactive clone?
Back
It is physically removed/killed
Front
In clonal anergy, what happens to the self-reactive clone?
Back
It survives but is rendered functionally unresponsive
Front
Clonal anergy results from which signaling pattern?
Back
Signal 1 without signal 2
Front
What reinforces clonal anergy beyond signal 1 without signal 2?
Back
Treg CTLA-4
Front
How many classes of hypersensitivity reactions are there?
Back
Four (Types I-IV)
Front
Type I hypersensitivity: principal antibody?
Back
IgE
Front
Type I hypersensitivity: principal effector cell?
Back
Mast cells (and basophils)
Front
Type I hypersensitivity is also called what?
Back
Immediate (anaphylactic/atopic) hypersensitivity
Front
What is the timing of Type I hypersensitivity?
Back
Within minutes of re-exposure
Front
What triggers the Type I reaction at the cellular level?
Back
IgE-triggered mast-cell degranulation
Front
Give two classic clinical examples of Type I hypersensitivity.
Back
Atopic dermatitis and anaphylaxis
Front
Atopic dermatitis is which hypersensitivity type?
Back
Type I (IgE/mast-cell mediated)
Front
Contact dermatitis vs atopic dermatitis: which is Type IV?
Back
Contact dermatitis (atopic dermatitis is Type I)
Front
What triggers mast-cell mediator release in Type I hypersensitivity?
Back
Allergen cross-linking IgE bound to mast-cell FcεRI receptors
Front
What mediators are released on mast-cell degranulation in Type I?
Back
Histamine and other mediators
Front
IgE antibody: what is its defining property?
Back
Binds strongly to mast cells
Front
Does IgE fix complement?
Back
No
Front
Is IgE abundant in saliva?
Back
No
Front
IgE mediates which hypersensitivity type (Type I or IV)?
Back
Type I
Front
Besides allergy, what immune defense is the IgE/mast-cell axis tied to?
Back
Anti-helminth (parasite) defense
Front
Which cell type joins IgE and mast cells in anti-parasite defense?
Back
Eosinophils
Front
Which tolerance mechanism is broken in atopic (allergic) individuals?
Back
Immunological facilitation
Front
Type II hypersensitivity: what is the target of the antibody?
Back
An antigen ON a cell or tissue (cell-surface/matrix antigen)
Front
Type II vs Type III: which involves antibody against a cell-bound antigen?
Back
Type II (Type III is against soluble antigen)
Front
Type II hypersensitivity: what are the main effector mechanisms of damage?
Back
Complement activation, phagocytes (opsonization), and ADCC
Front
Name two classic clinical examples of Type II hypersensitivity.
Back
Hemolytic disease of the newborn (HDN) and transfusion reactions
Front
Transfusion reactions are which hypersensitivity type?
Back
Type II
Front
Why are transfusion reactions Type II?
Back
Anti-A/anti-B antibody binds antigens on transfused RBC surface
Front
What destroys the RBCs in a transfusion reaction?
Back
Complement-mediated lysis and phagocytic clearance
Front
Type III hypersensitivity: what is the causative immune structure?
Back
Immune complexes (antibody bound to soluble antigen)
Front
In Type III hypersensitivity, what kind of antigen does antibody bind?
Back
Soluble antigen
Front
In Type III hypersensitivity, which cells arrive first at the site?
Back
Neutrophils (PMNs)
Front
In Type III, how is tissue damage actually produced?
Back
Deposited immune complexes activate complement, attracting neutrophils whose enzymes damage tissue

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