MMI 188B: T-Cell and B-Cell Immunity Review

Comprehensive practice flashcards in fill-in-the-blank style covering T-cell development, activation, subsets, effector functions, and B-cell humoral responses.

The primary lymphoid organ located above the heart where T cells develop is the __________.

thymus

Developing T cells within the thymus are known as __________.

thymocytes

The epithelial network that supports thymocyte development within the thymus is called the __________.

thymic stroma

T cells originate from progenitor cells in the __________ before migrating to mature in the thymus.

bone marrow

More than __________ of all developing T cells belong to the αβ T-cell lineage.

$$90\%$$

In the thymic cortex, cortical epithelial cells are responsible for mediating __________ selection.

positive

The thymic __________ contains more mature thymocytes and specialized cells involved in establishing self-tolerance.

medulla

In the thymus, dying thymocytes that fail developmental checkpoints are engulfed and cleared by __________.

macrophages

Medullary epithelial structures in the thymus associated with TSLP production are known as __________.

Hassallʼs corpuscles

Thymic stromal lymphopoietin (TSLP) activates thymic dendritic cells that support differentiation of CD4⁺ CD25⁺ __________ regulatory T cells.

FoxP3⁺

The age-related replacement of functional thymic tissue by __________ is known as thymic involution.

fat

The progressive decline in immune function with age is termed __________.

immunosenescence

Complete __________ syndrome is characterized by a failure of thymic development leading to profound T-cell deficiency.

DiGeorge

T-lineage commitment is directed by the cell-surface receptor __________ after its intracellular domain is cleaved and enters the nucleus.

Notch1

Early uncommitted thymic precursor cells express the cell-surface marker __________.

CD34

Committed precursors shared by both the αβ and γδ T-cell lineages express the cell-surface marker __________.

CD2

Double-negative (DN) thymocytes are defined by their lack of both __________ and CD8 co-receptors.

CD4

At the pre-T cell stage, the newly rearranged β chain pairs with the invariant surrogate chain __________.

pre-Tα (pTα)

Pre-TCR signaling utilizes the protein tyrosine kinase __________ to provide developmental checkpoints and survival signals.

Lck

Thymocytes at the double-positive stage simultaneously express both __________ co-receptors.

CD4 and CD8

Unlike the TCR β chain which rearranges V, D, and J segments, the TCR α chain contains only __________ segments.

V and J

The human TCR β-chain gene locus is located on chromosome __________.

$$7$$

The human TCR α-chain gene locus is located on chromosome __________.

$$14$$

The TCR β-chain locus permits rescue rearrangements because it contains two distinct __________ clusters.

Dβ–Jβ–Cβ

During TCR α-chain rearrangement, deletion of the δ locus produces an extrachromosomal circle called a __________.

T-cell receptor excision circle (TREC)

In cortical thymic epithelial cells, the specialized enzyme complex known as the __________ generates peptides used in positive selection of CD8 T cells.

thymoproteasome

During thymocyte positive selection, productive interaction with MHC class I molecules directs lineage commitment toward __________ T cells.

CD8

During thymocyte positive selection, productive interaction with MHC class II molecules directs lineage commitment toward __________ T cells.

CD4

In healthy circulating blood, CD4 T cells outnumber CD8 T cells by a ratio of approximately __________.

$$2:1$$

The elimination of thymocytes that bind self-peptide–self-MHC complexes too strongly is termed __________ selection.

negative

Medullary thymic epithelial cells express the transcription factor __________ to drive the expression of tissue-specific self-antigens.

AIRE

Loss-of-function mutations in the AIRE gene cause defective central self-tolerance resulting in the autoimmune disease __________.

APECED

Regulatory T cells (Treg) are a CD4 lineage defined by the lineage-specific transcription factor __________.

FoxP3

The two primary suppressive cytokines secreted by regulatory T cells to mediate peripheral tolerance are TGF-β and __________.

IL-10

The initial activation of a naïve T cell upon encountering its specific antigen on a mature dendritic cell is known as T-cell __________.

priming

Compared to naïve T cells, differentiated effector T cells have a __________ dependence on co-stimulation for activation.

lower

While most effector T cells migrate to peripheral sites of infection, __________ cells remain in lymphoid tissues to provide B-cell help.

TFH

The process by which an extracellular antigen captured by a dendritic cell is presented on MHC class I molecules to CD8 T cells is called __________.

cross-presentation

Initial tethering and rolling of naïve T cells on high endothelial venules (HEVs) is mediated by L-selectin binding to CD34 and __________.

GlyCAM-1

Firm adhesion and arrest of naïve T cells on the HEV endothelium occurs when the integrin LFA-1 binds to __________.

ICAM-1

T cells that do not encounter their specific antigen exit the lymph node via efferent lymphatics along a gradient of __________.

sphingosine-1-phosphate (S1P)

Initial contact between a T cell and a dendritic cell is mediated by T-cell ICAM-3 binding to __________ on the dendritic cell.

DC-SIGN

Adhesion between a T cell and an APC is supported by the interaction between T-cell CD2 and __________ on the APC.

LFA-3

The homing of effector T cells into inflamed peripheral tissue is mediated by integrin VLA-4 binding to endothelial __________.

VCAM-1

Signal 2 for naïve T-cell activation is provided by co-stimulation between CD28 on the T cell and __________ on the APC.

B7

Antigen recognition by a naïve T cell in the absence of co-stimulation produces functional unresponsiveness, termed __________.

anergy

CD28 co-stimulation increases T-cell survival by upregulating expression of the anti-apoptotic protein __________.

Bcl-xL

Following activation, T cells express the inhibitory receptor __________, which binds B7 with higher affinity than CD28 to suppress proliferation.

CTLA4

The CD4 co-receptor binds to the conserved invariant __________ domain of MHC class II molecules.

β2

The CD8 co-receptor binds to the conserved invariant __________ domain of MHC class I molecules.

α3

The TCR complex transmits intracellular activation signals through signaling motifs known as __________ found on CD3 and ζ chains.

ITAMs

Following phosphorylation of CD3 and ζ chain ITAMs by Lck, the cytoplasmic tyrosine kinase __________ is recruited and activated.

ZAP-70

Within the immunological synapse, the central SMAC (c-SMAC) contains the TCR, CD28, and the signaling kinase __________.

PKC-θ

Within the immunological synapse, the peripheral SMAC (p-SMAC) contains LFA-1, ICAM-1, and the cytoskeletal protein __________.

talin

Formation of the high-affinity trimeric IL-2 receptor on activated T cells requires induction of the __________ chain (CD25).

α

The lineage-defining master transcription factor for TH1 differentiation is __________.

T-bet

The priority effector cytokine secreted by TH1 cells to activate macrophages against intracellular pathogens is __________.

IFN-γ

The lineage-defining master transcription factor for TH2 differentiation is __________.

GATA3

In addition to IL-4, TH2 cells produce the cytokine __________, which specifically promotes eosinophil activation and recruitment.

IL-5

The lineage-defining master transcription factor for TH17 differentiation is __________.

RORγT

TH17 cells produce the signature cytokine __________, which enhances neutrophil recruitment to clear extracellular bacteria and fungi.

IL-17

The defining master transcription factor for follicular helper T (TFH) cells is __________.

Bcl-6

TFH cells secrete the priority cytokine __________, which drives B-cell proliferation, somatic hypermutation, and class switching.

IL-21

In __________ leprosy, an effective TH1-dominant response activates macrophages and controls Mycobacterium leprae infection.

tuberculoid

The cytotoxic granule protein that polymerizes to form pores and facilitates granzyme entry into target cells is __________.

perforin

The cytotoxic granule protein that directly damages microbial membranes and exhibits antimicrobial activity is __________.

granulysin

Within cytotoxic granules, the proteoglycan __________ stabilizes and organizes the lytic complex.

serglycin

Full macrophage activation by TH1 cells requires two cooperative signals: IFN-γ and __________ binding to CD40.

CD40L

Upon BCR antigen binding, phosphorylation of ITAMs on Igα and Igβ is mediated by Src-family kinases, including Blk, Fyn, and __________.

Lyn

Following BCR ITAM phosphorylation, the downstream protein tyrosine kinase __________ is recruited and activated in B cells.

Syk

Within the B-cell co-receptor complex, the CR2 (CD21) component binds to the complement breakdown fragment __________ attached to antigen.

C3d

T-independent antibody responses against repetitive polysaccharide antigens are predominantly mediated by marginal-zone B cells and __________ B cells.

B-1

Unlike hematopoietic dendritic cells, follicular dendritic cells (FDCs) retain and display __________ antigen on their surface using complement and Fc receptors.

intact

In the germinal center dark zone, large, rapidly dividing B cells undergoing somatic hypermutation are called __________.

centroblasts

Hyper-IgM syndrome is caused by a genetic deficiency in the X-linked gene encoding __________, severely impairing antibody class switching.

CD40L