Summer Immuno Lecture 9 Flashcards

A developing T cell first learns self-tolerance in which organ?
A. Spleen
B. Lymph node
C. Bone marrow
D. Thymus

The thymic process that teaches developing T cells tolerance to self is called what?
A. Peripheral tolerance
B. Central tolerance induction
C. Clonal selection
D. Affinity maturation

T-cell precursors enter the thymus after exiting which site?
A. Bone marrow
B. Spleen
C. Peyer patch
D. Lymph node

A newly arrived thymocyte lacks CD4, CD8, and TCR. What best describes it?
A. Single-positive
B. Double-positive
C. Receptor-negative immature
D. Fully mature naive

After entering the thymus, immature T cells migrate outward to proliferate in which region?
A. Medulla
B. Capsule
C. Hilum
D. Cortex

In the thymic cortex, immature T cells begin gene rearrangement to form which receptor?
A. BCR
B. TCR
C. Fc receptor
D. TLR

After successful TCR rearrangement, immature thymocytes begin expressing TCR plus which co-receptors?
A. CD4 and CD8
B. CD28 and B7
C. Fas and FasL
D. PD-1 and PD-L1

A thymocyte expressing both CD4 and CD8 is called what?
A. Single-positive
B. Double-negative
C. Double-positive
D. Centrally tolerant

A receptor-negative immature thymocyte is protected from apoptosis by high expression of what?
A. Fas
B. Bcl-2
C. AIRE
D. CCR7

Very immature thymocytes express little to no which apoptosis-related molecule?
A. CD4
B. TCR
C. Bcl-2
D. Fas antigen

The thymic test for MHC restriction is called what?
A. Positive selection
B. Negative selection
C. Peripheral deletion
D. Somatic hypermutation

Positive selection is performed mainly by which thymic cells?
A. mTECs
B. FDCs
C. cTECs
D. Tfh cells

Positive selection asks whether a thymocyte’s TCR can recognize what?
A. Foreign antigen
B. Complement fragments
C. B-cell follicles
D. Self-MHC

A thymocyte cannot recognize self-MHC during positive selection. What is its fate?
A. Class switching
B. Apoptosis
C. Tfh licensing
D. Germinal rescue

cTECs generate some self-peptides for presentation by digesting their own cytoplasm through what process?
A. Degranulation
B. Phagocytosis
C. Autophagy
D. Opsonization

cTECs can load autophagy-derived peptides onto which molecule?
A. Class II MHC
B. Fc receptor
C. CD40 ligand
D. TCR complex

cTECs may also present protein fragments taken from which source?
A. Bloodstream
B. Peyer patch lumen
C. Splenic red pulp
D. Thymus environment

During or shortly after positive selection, thymocytes usually become what?
A. Double-negative
B. Single-positive
C. Antibody-secreting
D. Receptor-negative

After a thymocyte recognizes self-MHC, it begins expressing which chemokine receptor?
A. CCR7
B. CXCR5
C. CXCL13
D. ICOSL

CCR7 expression directs selected thymocytes toward which thymic region?
A. Cortex
B. Capsule
C. Medulla
D. Trabeculae

The medulla attracts CCR7-positive thymocytes because it contains abundant what?
A. AIRE protein
B. CCR7 ligands
C. BCR complexes
D. CD40 ligands

Negative selection occurs mainly in which thymic region?
A. Cortex
B. Capsule
C. Follicle
D. Medulla

Negative selection asks whether the thymocyte recognizes what?
A. Self-peptides
B. Foreign antibodies
C. Complement fragments
D. Chemokine gradients

A thymocyte strongly recognizes self-peptide on MHC. What happens?
A. It becomes CD8
B. It enters blood
C. It is destroyed
D. It becomes Tfh

Failure of negative selection can predispose to what?
A. IgA deficiency
B. Autoimmune disease
C. Neutrophil death
D. Complement depletion

Which medullary cell helps test thymocytes for self-tolerance?
A. cTEC
B. FDC
C. NK cell
D. mTEC

mTECs help delete autoreactive T cells through which process?
A. Positive selection
B. Class switching
C. Negative selection
D. Antigen plucking

mTECs generate self-peptides partly through what cellular process?
A. Autophagy
B. Degranulation
C. Exocytosis
D. Opsonization

mTECs express which transcription factor to display tissue-specific antigens?
A. CCR7
B. FasL
C. Bcl-2
D. AIRE

AIRE is best classified as what?
A. Chemokine receptor
B. Transcription factor
C. Death receptor
D. Co-stimulatory ligand

AIRE allows mTECs to express antigens normally found where?
A. B-cell follicles
B. Splenic sinusoids
C. Peripheral tissues
D. Bone marrow only

mTECs use AIRE to express more than how many tissue-specific proteins?
A. One thousand
B. Ten
C. One hundred
D. One million

A child has defective AIRE. Which process is most directly impaired?
A. TCR gene rearrangement
B. Negative selection
C. CD8 lineage choice
D. Cortex proliferation

A thymocyte fails to bind self-MHC. Which selection step eliminates it?
A. Positive selection
B. Negative selection
C. AICD contraction
D. Tfh licensing

A thymocyte binds self-peptide too strongly. Which selection step eliminates it?
A. Somatic hypermutation
B. Positive selection
C. Negative selection
D. Germinal rescue

Which thymic cell type is most associated with AIRE expression?
A. cTEC
B. mTEC
C. FDC
D. Tfh cell

Which thymic cell type is most associated with testing MHC restriction?
A. mTEC
B. Tfh cell
C. cTEC
D. FDC

What is the purpose of central tolerance induction?
A. Increase antibody affinity
B. Activate naive B cells
C. Prevent self-reactive T cells
D. Recruit neutrophils

Why is AIRE important for central tolerance?
A. It binds CD8 directly
B. It creates CCR7 ligands
C. It prevents TCR rearrangement
D. It displays peripheral antigens

The thymocyte migration sequence is best summarized as which pathway?
A. Medulla to cortex
B. Cortex to medulla
C. Spleen to thymus
D. Follicle to PALS

A second thymic cell type helps test developing T cells for self-tolerance in the medulla. What is this cell called?
A. Follicular dendritic cell
B. Thymic dendritic cell
C. Cortical epithelial cell
D. Marginal-zone B cell

Thymic dendritic cells are abbreviated as what?
A. FDC
B. cTEC
C. TDC
D. Tfh

Thymic dendritic cells contribute to tolerance testing by presenting what?
A. Foreign antigens only
B. Self-antigens
C. Complement fragments
D. Antibody Fc regions

TDCs present self-antigens on which molecules?
A. MHC molecules
B. BCR complexes
C. Fc receptors
D. Chemokine receptors

In addition to making self-antigens, TDCs also receive self-antigens from which cells?
A. cTECs
B. mTECs
C. FDCs
D. Tfh cells

Medullary thymic dendritic cells are resident cells of which region?
A. Thymic cortex
B. Splenic PALS
C. Thymic medulla
D. Lymph-node cortex

Medullary TDCs develop from which precursor source?
A. Bone-marrow-derived precursors
B. Thymic epithelial precursors
C. Splenic stromal precursors
D. Germinal-center precursors

The final thymic output should recognize which structure?
A. Free self-antigen
B. Complement-opsonized antigen
C. Self MHC-peptide complex
D. Antibody constant region

Mature thymic graduates should not recognize self-antigens presented by which cells?
A. B cells and FDCs
B. TDCs and mTECs
C. NK cells and CTLs
D. cTECs and neutrophils

A T cell exits the thymus after testing. Which receptor profile is desired?
A. Binds self-antigen strongly
B. Ignores all MHC molecules
C. Recognizes self MHC-peptide
D. Recognizes antibody Fc regions

A young thymus tests approximately how many double-positive cells daily?
A. 2 million
B. 6 million
C. 60 million
D. 600 million

Of the daily double-positive thymocytes tested, approximately how many single-positive cells exit?
A. 20 million
B. 2 million
C. 60 million
D. 600,000

Most double-positive thymocytes tested daily undergo what fate?
A. Clonal expansion
B. Class switching
C. Somatic hypermutation
D. Apoptosis

Roughly what percentage of tested thymocytes mature and exit daily?
A. 30%
B. 10%
C. 3%
D. 90%

The Goldilocks hypothesis addresses how one TCR can signal which outcomes?
A. Switching, mutation, apoptosis
B. Selection, deletion, activation
C. Opsonization, lysis, chemotaxis
D. Trafficking, adhesion, rolling

According to the Goldilocks hypothesis, why do so few thymocytes mature?
A. Most cannot signal correctly
B. Most lack bone-marrow origin
C. Most become plasma cells
D. Most migrate into spleen

A T cell survives thymic testing because its TCR interaction strength is “just right.” What does this imply?
A. Strong self-antigen binding
B. No MHC recognition
C. Balanced self-MHC recognition
D. Direct antibody binding

During positive selection, surviving T cells should have what type of interaction with self MHC-peptide?
A. Relatively weak
B. Extremely strong
C. Completely absent
D. Antibody-mediated

Why must self MHC-peptide interaction be relatively weak?
A. Allows focus on antigen
B. Prevents MHC expression
C. Blocks APC activation
D. Eliminates CD4 cells

In the Goldilocks model, interaction with self-peptide presented by medullary TDCs should be what?
A. Very strong
B. Very weak
C. Completely absent
D. Antibody dependent

A thymocyte binds self-peptide on medullary TDCs too strongly. What happens?
A. It becomes nTreg always
B. It is killed
C. It exits rapidly
D. It becomes CD8 only

A thymocyte’s interaction with self-peptide is weak enough to avoid deletion but sufficient for later APC interaction. What does this represent?
A. Goldilocks signaling
B. BCR crosslinking
C. Fc receptor binding
D. Complement activation

Even after thymic exit, many T cells die because they fail to find what?
A. B7 proteins
B. Cognate antigen
C. Fc regions
D. Complement fragments

If a naive T cell never finds cognate antigen, it dies after approximately how long?
A. 2 days
B. 1 week
C. 6 weeks
D. 6 months

Some T cells pass negative selection despite being self-reactive because their antigen is what?
A. Very common
B. Very rare
C. Bacterial only
D. Antibody-bound

Escaped self-reactive T cells often fail to cause disease because their cognate antigen is unlikely to be found where?
A. Bone marrow
B. Secondary lymphoid organs
C. Thymic cortex
D. Blood plasma

A T cell escapes deletion because its rare tissue-specific antigen was not encountered. What is this cell?
A. Self-reactive T cell
B. Marginal-zone B cell
C. Follicular helper cell
D. Thymic dendritic cell

Rare tissue-specific cognate antigens may allow some T cells to pass which process?
A. Positive selection
B. Negative selection
C. Class switching
D. Somatic hypermutation

In the thymic medulla, a subset of CD4 T cells becomes which regulatory population?
A. iTregs
B. Tfh cells
C. nTregs
D. CTLs

Natural regulatory T cells are selected mainly in which location?
A. Thymic cortex
B. Thymic medulla
C. Splenic red pulp
D. Lymph-node medulla

nTregs arise from which broad T-cell type?
A. CD4 T cells
B. CD8 T cells
C. NK cells
D. B cells

T cells with weak affinity for self-antigens are generally selected to become what?
A. Th cells
B. nTregs
C. Plasma cells
D. Macrophages

T cells with too strong affinity for self-antigens are usually what?
A. Expanded
B. Destroyed
C. Class-switched
D. Exported

T cells with intermediate affinity for self-antigens are selected to become what?
A. Th17 cells
B. CTLs
C. nTregs
D. FDCs

nTreg-selected cells are induced to express which gene?
A. AIRE
B. Bcl-2
C. GlyCAM-1
D. Foxp3

Foxp3 expression is associated with which regulatory lineage?
A. Regulatory T cells
B. Marginal-zone B cells
C. Thymic dendritic cells
D. Cortical epithelial cells

nTregs become activated when they encounter which antigen type?
A. Self-antigen
B. Bacterial LPS
C. Viral dsRNA
D. Antibody Fc

Once activated, nTregs suppress which cells?
A. Plasma B cells
B. Potentially self-reactive T cells
C. Resident macrophages only
D. Follicular dendritic cells

The main protective role of nTregs is preventing damage from which cells?
A. Self-reactive T cells
B. Overactive neutrophils
C. IgE-producing B cells
D. Antigen-presenting macrophages

Both nTregs and iTregs express which protein?
A. CTLA-4
B. AIRE
C. Foxp3
D. CD40L

Which regulatory T-cell type protects mainly against self-reactive T cells?
A. iTregs
B. nTregs
C. Th0 cells
D. Tfh cells

Which regulatory T-cell type restrains overreaction to foreign invaders?
A. nTregs
B. CTLs
C. Tfh cells
D. iTregs

nTregs and iTregs both express Foxp3 but differ mainly in what?
A. Target of suppression
B. MHC class restriction
C. TCR gene number
D. Bone marrow origin

Which regulatory cell is naturally selected within the thymus?
A. iTreg
B. Th17
C. nTreg
D. Tfh

Which regulatory cell is inducible from naive Th cells in peripheral settings?
A. nTreg
B. iTreg
C. CTL
D. TDC

A potentially self-reactive virgin T cell leaves normal circulation and enters kidney tissue. Which safety mechanism protects against autoimmunity here?
A. Central tolerance induction
B. Peripheral tolerance induction
C. Somatic hypermutation
D. Missing-self recognition

A virgin T cell recognizes cognate antigen on a nonprofessional tissue cell but receives no second signal. What happens?
A. It becomes anergic
B. It undergoes class switching
C. It becomes a Tfh cell
D. It activates macrophages

A virgin T cell recognizes antigen on a normal kidney cell but does not activate. What signal is missing?
A. Complement fixation
B. TCR rearrangement
C. Co-stimulation
D. Fc binding

Why does a normal kidney cell usually fail to activate a virgin T cell?
A. It lacks B7
B. It lacks MHC I
C. It secretes IgA
D. It expresses Foxp3

A virgin T cell becomes anergized after recognizing antigen without co-stimulation. What is its eventual fate?
A. Class switching
B. NK licensing
C. Death
D. Memory formation

A rare self-reactive virgin T cell receives such strong antigen crosslinking that co-stimulation is bypassed. Which backup mechanism limits it?
A. Receptor editing
B. Missing-self recognition
C. Activation-induced cell death
D. Somatic hypermutation

Instead of testing every single T cell perfectly, the immune system uses at least how many tolerance mechanisms?
A. Two
B. Three
C. Four
D. Five

Most B cells are tolerized in which location?
A. Thymus
B. Bone marrow
C. Spleen
D. Lymph node

A developing B cell recognizes self-antigen in the bone marrow. What process gives it another chance?
A. Receptor editing
B. Positive selection
C. AICD
D. Missing-self recognition

Receptor editing most directly involves rearrangement of which B-cell component?
A. Heavy chain
B. Fc region
C. J chain
D. Light chain

A germinal-center B cell undergoes somatic hypermutation and develops self-reactivity. Why is activation by FDCs unlikely?
A. Self-antigens lack MHC
B. Self-antigens usually aren't opsonized
C. FDCs lack antigen receptors
D. FDCs only bind T cells

A self-reactive B cell arises after somatic hypermutation. Why is T-cell help unlikely?
A. Matching Th cells are absent
B. B cells cannot present antigen
C. CD40 is always absent
D. Th cells lack MHC II

A virus-infected cell downregulates Class I MHC to evade CTLs. Which immune cell can kill it?
A. Th2 cell
B. Plasma cell
C. NK cell
D. B cell

NK-cell killing of cells with reduced Class I MHC is called what?
A. Receptor editing
B. Peripheral tolerance
C. Central tolerance
D. Missing-self recognition

In missing-self recognition, NK cells kill because they fail to receive what signal?
A. Co-stimulatory signal
B. Inhibitory signal
C. Chemokine signal
D. TCR signal

The inhibitory signal for NK cells depends on recognition of which host molecule?
A. Class I MHC
B. Class II MHC
C. CD40 ligand
D. Antibody Fc

An NK cell cannot recognize the body’s Class I MHC. Without licensing, what risk would this create?
A. Autoimmune NK killing
B. Failed BCR editing
C. Excess IgE switching
D. Thymic T-cell deletion

NK cells must be licensed through which screening process?
A. Negative selection
B. Receptor editing
C. Positive selection
D. Class switching

During NK-cell licensing, functional NK cells must bind what?
A. Foreign antigen
B. Self-MHC
C. Complement fragments
D. B7 proteins

NK cells that cannot bind self-MHC during licensing become what?
A. Anergized
B. Activated
C. Class-switched
D. Opsonized

Which scenario best illustrates peripheral tolerance induction?
A. T cell deleted in thymus
B. B cell edits light chain
C. T cell sees antigen, no B7
D. NK cell detects missing MHC

Which scenario best illustrates receptor editing?
A. Self-reactive B cell rearranges light chain
B. CTL dies after repeated activation
C. NK cell binds self-MHC
D. Th cell becomes Tfh

Which scenario best illustrates missing-self recognition?
A. T cell lacks co-stimulation
B. B cell lacks Th help
C. NK cell senses low MHC I
D. mTEC expresses AIRE

A self-reactive B cell after somatic hypermutation usually fails because it cannot efficiently get which two supports?
A. FDC antigen and Th help
B. CTL killing and FasL
C. NK licensing and IL-2
D. AIRE and TDC antigen

Which tolerance mechanism is specific to B cells in this material?
A. Peripheral anergy
B. Receptor editing
C. Missing-self recognition
D. Activation-induced death