T-cell receptors come in which two major types?
A. CD4 and CD8
B. αβ and γδ
C. Igα and Igβ
D. Class I and II

B. αβ and γδ

B cells and T cells both use which proteins to initiate receptor gene rearrangement?
A. TAP1 and TAP2
B. CD3 and CD28
C. LMP2 and LMP7
D. RAG1 and RAG2

D. RAG1 and RAG2

Over 95% of circulating T cells carry which TCR type?
A. αβ TCR
B. γδ TCR
C. CD1 TCR
D. NK-like TCR

A. αβ TCR

Most circulating αβ T cells also express which co-receptor pattern?
A. Both CD4 and CD8
B. Neither CD4 nor CD8
C. Either CD4 or CD8
D. CD3 without co-receptors

C. Either CD4 or CD8

A T cell recognizes peptide displayed on an MHC molecule. Which receptor type most likely did this?
A. γδ TCR
B. αβ TCR
C. BCR
D. CD1 receptor

B. αβ TCR

Unlike B cells, T cells cannot improve receptor affinity by which process?
A. Hypermutation
B. Crosslinking
C. Co-stimulation
D. Productive rearrangement

A. Hypermutation

γδ T cells are considered nontraditional because they generally lack what?
A. CD3 signaling proteins
B. Rearranged receptors
C. Surface TCRs
D. CD4 or CD8

D. CD4 or CD8

γδ T cells are most abundant in which locations?
A. Deep sterile organs
B. Bone marrow sinusoids
C. Barrier-contact tissues
D. Fetal bloodstream only

C. Barrier-contact tissues

Which site is especially rich in γδ T cells?
A. Intestine
B. Kidney cortex
C. Cardiac muscle
D. Brain parenchyma

A. Intestine

Compared with αβ TCRs and BCRs, γδ receptors are generally what?
A. More polymorphic
B. More hypermutated
C. More antibody-like
D. Less diverse

D. Less diverse

γδ TCR rearrangement tends to favor what?
A. Random Fc regions
B. Certain gene segments
C. Complement proteins
D. CD40L expression

B. Certain gene segments

A nontraditional T cell has both T-cell and NK-cell properties. What is it?
A. γδ T cell
B. Regulatory T cell
C. NKT cell
D. Plasma T cell

C. NKT cell

NKT cells resemble traditional T cells because they have which receptor type?
A. γδ receptors
B. B-cell receptors
C. IgE receptors
D. αβ receptors

D. αβ receptors

NKT cells resemble NK cells because they share what?
A. NK-like properties
B. BCR signaling
C. IgA secretion
D. CD40 expression

A. NK-like properties

NKT receptors can recognize which antigen class?
A. Proteins
B. Carbohydrates
C. Lipids
D. Nucleic acids

C. Lipids

NKT cells recognize lipid antigens presented by which molecule?
A. Class I MHC
B. CD1
C. Class II MHC
D. C1 complex

B. CD1

NKT cells differ from conventional αβ T cells because NKT cells recognize lipids instead of what?
A. Protein fragments
B. C3 fragments
C. Antibody Fc regions
D. Histamine products

A. Protein fragments

The αβ TCR extracellular domain primarily does what?
A. Signals nucleus directly
B. Degrades antigen
C. Binds its ligand
D. Produces cytokines

C. Binds its ligand

Why does the αβ TCR require accessory signaling proteins?
A. It lacks antigen specificity
B. Its ligand is soluble
C. It cannot bind MHC
D. Its cytoplasmic tails are short

D. Its cytoplasmic tails are short

The TCR signaling complex is called what?
A. CD28
B. CD3
C. CD40
D. CD1

B. CD3

The CD3 complex contains which protein set?
A. α, β, μ, κ
B. CD4, CD8, CD28
C. γ, δ, ε, ζ
D. HLA-A, B, C

C. γ, δ, ε, ζ

The γ and δ chains in CD3 should not be confused with what?
A. γδ TCR chains
B. IgG subclasses
C. CD4 co-receptors
D. MHC II chains

A. γδ TCR chains

Like BCRs, TCRs often require what for strong signaling?
A. Antibody secretion
B. Complement fixation
C. Hypermutation
D. Crosslinking

D. Crosslinking

TCR clustering occurs on which part of the T cell?
A. Nuclear membrane
B. Cell surface
C. Mitochondrial matrix
D. ER lumen

B. Cell surface

In the thymus, strong recognition of self peptide-MHC triggers what?
A. T-cell suicide
B. T-cell activation
C. T-cell anergy
D. T-cell class switching

A. T-cell suicide

Thymic suicide of self-reactive T cells helps prevent what?
A. Viral entry
B. Antibody production
C. Autoimmunity
D. Complement fixation

C. Autoimmunity

A mature T cell recognizes antigen-MHC but receives no co-stimulation. What may occur?
A. Hypermutation
B. Anergy
C. Class switching
D. ADCC

B. Anergy

T-cell anergy is best described as functional what?
A. Activation
B. Expansion
C. Memory formation
D. Neutering

D. Neutering

A TCR receives cognate antigen plus co-stimulation. What occurs?
A. Deletion
B. Anergy
C. Activation
D. Receptor editing

C. Activation

TCR signaling in the thymus differs because it tests mainly for what?
A. Foreign antigen strength
B. Complement fixation
C. B-cell help
D. Self-reactivity

D. Self-reactivity

Later in life, TCR recognition without co-stimulation helps prevent what?
A. Peptide loading
B. Improper activation
C. CD3 expression
D. MHC formation

B. Improper activation

Helper and killer T cells remain matched to correct MHC classes using what?
A. CD4/CD8 co-receptors
B. Igα/Igβ proteins
C. C3b receptors
D. Fas ligand

A. CD4/CD8 co-receptors

CD4 co-receptors bind which MHC class?
A. Class I MHC
B. CD1 molecules
C. Nonclassical MHC
D. Class II MHC

D. Class II MHC

CD8 co-receptors bind which MHC class?
A. Class II MHC
B. CD1 molecules
C. Class I MHC
D. Invariant chain

C. Class I MHC

A developing thymocyte expresses both CD4 and CD8. What is it called?
A. Single-positive
B. Double-negative
C. Double-positive
D. Fully anergized

C. Double-positive

Mature T cells usually become what after MHC-specific selection?
A. Double-positive
B. Double-negative
C. Triple-positive
D. Single-positive

D. Single-positive

If CD4 is activated during thymic maturation, what happens to CD8?
A. It is downregulated
B. It becomes CD3
C. It binds CD1
D. It hypermutates

A. It is downregulated

If CD8 is activated during thymic maturation, what happens to CD4?
A. It becomes CD40L
B. It remains coexpressed forever
C. It is downregulated
D. It binds β2-microglobulin

C. It is downregulated

A cell with CD8 is most consistent with which T-cell function?
A. Killer T-cell function
B. Helper T-cell function
C. B-cell activation only
D. Mast-cell degranulation

A. Killer T-cell function

A cell with CD4 is most consistent with which T-cell function?
A. NK-like cytotoxicity
B. γδ barrier surveillance
C. B-cell receptor signaling
D. Helper T-cell function

D. Helper T-cell function

A T cell lacks CD4 and CD8 but has a TCR. Which T-cell type best fits?
A. αβ T cell
B. γδ T cell
C. Helper T cell
D. CTL

B. γδ T cell

A T cell recognizes peptide-MHC and expresses CD8. Which receptor type is most likely?
A. γδ TCR
B. NKT lipid receptor
C. αβ TCR
D. BCR

C. αβ TCR

A mucosal T cell lacks CD4/CD8 and uses limited receptor diversity. What is most likely?
A. Helper T cell
B. Cytotoxic αβ T cell
C. Plasma B cell
D. γδ T cell

D. γδ T cell

Which molecules initiate gene-segment splicing in both B and T cells?
A. CD4 and CD8
B. CD40 and CD40L
C. RAG1 and RAG2
D. B7 and CD28

C. RAG1 and RAG2

Productive rearrangement in lymphocytes depends on mix-and-match splicing of what?
A. Gene segments
B. Fc regions
C. C1 inhibitors
D. MHC grooves

A. Gene segments

T cells cannot alter TCR affinity later because they lack what process?
A. Co-stimulation
B. Somatic hypermutation
C. CD3 signaling
D. RAG rearrangement

B. Somatic hypermutation

T-cell co-stimulation commonly occurs when APC B7 binds which T-cell receptor?
A. CD28
B. CD40
C. CD4
D. CD8

A. CD28

Which APC surface protein provides classic T-cell co-stimulation?
A. CD3
B. CD40L
C. B7
D. TCR

C. B7

A naive T cell receives TCR crosslinking but no B7-CD28 signal. Which signal is missing?
A. Antigen signal
B. Co-stimulation
C. MHC recognition
D. TCR clustering

B. Co-stimulation

Once a naive T cell becomes experienced, the TCR-nucleus connection becomes what?
A. Weaker
B. Deleted
C. Unchanged
D. Strengthened

D. Strengthened

Experienced T cells require less co-stimulation because signaling to the nucleus is more what?
A. Random
B. Efficient
C. Antibody-dependent
D. MHC-independent

B. Efficient

A helper T cell recognizes antigen on an activated dendritic cell. What first helps keep the cells close?
A. Complement fragments
B. Soluble antibodies
C. Perforin pores
D. Adhesion molecules

D. Adhesion molecules

During helper T-cell activation, CD4 clips onto which dendritic-cell molecule?
A. Class I MHC
B. CD28
C. Class II MHC
D. CD40L

C. Class II MHC

TCR binding to MHC-peptide causes further upregulation of what?
A. Fas ligand
B. Adhesion molecules
C. IgE receptors
D. Complement proteins

B. Adhesion molecules

Increased adhesion after TCR engagement mainly causes the two cells to become what?
A. More tightly attached
B. Less responsive
C. Antibody coated
D. Fully separated

A. More tightly attached

Clustering of TCRs and adhesion molecules creates which structure?
A. Germinal center
B. Phagolysosome
C. Immunological synapse
D. Complement pore

C. Immunological synapse

The immunological synapse forms at which location?
A. Inside the nucleus
B. In the thymic cortex
C. T cell-APC contact point
D. Inside the lysosome

C. T cell-APC contact point

Engagement of helper T-cell TCRs upregulates which surface protein?
A. CD40L
B. CD28
C. B7
D. CD8

A. CD40L

CD40L appears on which cell during dendritic-cell interaction?
A. Dendritic cell
B. Macrophage
C. Bacterium
D. T cell

D. T cell

CD40L binds which protein on the dendritic cell?
A. CD28
B. CD40
C. CD4
D. CD8

B. CD40

CD40 is found on which cell in this interaction?
A. Dendritic cell
B. Helper T cell
C. Killer T cell
D. Neutrophil

A. Dendritic cell

CD40-CD40L binding increases dendritic-cell expression of what?
A. MHC destruction proteins
B. Antibody receptors
C. Co-stimulatory molecules
D. Complement inhibitors

C. Co-stimulatory molecules

CD40 engagement helps the dendritic cell do what?
A. Lose all MHC
B. Become an antibody
C. Stop activating T cells
D. Live longer

D. Live longer

Why does increased dendritic-cell lifespan matter?
A. It stops antigen display
B. It activates more T cells
C. It kills infected cells
D. It blocks CD28

B. It activates more T cells

Helper T cells recognize dendritic-cell antigen while using which co-receptor?
A. CD8
B. CD28 only
C. CD4
D. B7

C. CD4

Killer T cells are activated similarly to helper T cells by encountering what?
A. Activated dendritic cells
B. Resting erythrocytes
C. Free antibodies
D. Complement pores

A. Activated dendritic cells

For initial activation, killer T cells also require which signal?
A. IgE crosslinking
B. Complement fixation
C. Co-stimulation
D. Histamine release

C. Co-stimulation

Full killer T-cell activation requires assistance from which cells?
A. NK cells
B. Helper T cells
C. Plasma cells
D. Mast cells

B. Helper T cells

Fully activated killer T cells can do all except which state?
A. Kill inefficiently
B. Proliferate robustly
C. Become memory CTLs
D. Kill efficiently

A. Kill inefficiently

Helper T-cell assistance allows CTLs to develop into which long-term population?
A. Plasma CTLs
B. Naive CTLs
C. Anergic CTLs
D. Memory CTLs

D. Memory CTLs

Why is a mechanism needed for helper-assisted CTL activation?
A. CTLs lack TCRs
B. DCs lack MHC
C. Helpers cannot bind APCs
D. Three-cell meeting is unlikely

D. Three-cell meeting is unlikely

Which model says helper T cells “license” dendritic cells?
A. Sequential model
B. Menage a Trois
C. Cross-presentation model
D. Anergy model

A. Sequential model

In the Sequential Model, helper T cells first activate and license which cell?
A. Killer T cell
B. Dendritic cell
C. Plasma cell
D. Neutrophil

B. Dendritic cell

Licensed dendritic cells can then fully help CTLs without what?
A. Class I MHC
B. Cytokine production
C. Helper T cell present
D. Co-stimulatory molecules

C. Helper T cell present

In the Sequential Model, licensed dendritic cells begin expressing more class I MHC and what else?
A. Cytokines and surface molecules
B. IgA and IgE
C. Perforin and granzymes
D. C1 and C9

A. Cytokines and surface molecules

Licensing improves dendritic-cell ability to activate which cells?
A. B cells
B. Macrophages
C. Mast cells
D. CTLs

D. CTLs

The Menage a Trois model depends partly on helper T cell-DC coupling lasting how long?
A. Seconds
B. Minutes
C. Several hours
D. Several weeks

C. Several hours

In the Menage a Trois model, helper T cell-DC coupling produces what?
A. IgG
B. Chemokines
C. Histamine
D. C1 inhibitor

B. Chemokines

Those chemokines attract which cells to the dendritic-cell site?
A. B cells
B. Killer T cells
C. Mast cells
D. Neutrophils

B. Killer T cells

In the Menage a Trois model, simultaneous meeting becomes more likely because coupling is what?
A. Instantaneous
B. Absent
C. Prolonged
D. Antibody-mediated

C. Prolonged

Which model does not require direct helper T-cell presence during CTL activation?
A. Menage a Trois
B. Anergy model
C. Synapse model
D. Sequential model

D. Sequential model

Which model recruits CTLs to an existing helper T cell-dendritic cell pair?
A. Menage a Trois
B. Sequential model
C. CD40-only model
D. Complement model

A. Menage a Trois

Which event specifically strengthens dendritic-cell co-stimulatory capacity?
A. CD8-MHC I binding
B. CD28 loss
C. CD40-CD40L binding
D. IgE degranulation

C. CD40-CD40L binding

Which event specifically increases adhesion during helper T-cell activation?
A. TCR-MHC binding
B. C1 activation
C. IgA transport
D. NK degranulation

A. TCR-MHC binding

Which structure represents organized TCR and adhesion clustering?
A. Phagosome
B. Immunological synapse
C. Proteasome
D. Germinal center

B. Immunological synapse

Which signal pair is needed for naive T-cell activation?
A. C3b and C5b
B. IgM and IgD
C. Histamine and IgE
D. TCR plus co-stimulation

D. TCR plus co-stimulation