Video: Activation of T-Cells and B-Cells - Vocabulary Flashcards

75 vocabulary flashcards covering key concepts from the lecture notes on antigen presentation, T and B cell activation, germinal centers, and checkpoint therapies.

Antigen-presenting cells (APCs)

Cells that process and present peptide antigens on MHC to T cells, initiating adaptive immune activation.

B cells, Macrophages, Dendritic Cells

Phagocytosis

Engulfment and internalization of pathogens or antigens by phagocytes.

Antigen processing

Processing of internalized antigens into peptides for MHC presentation.

MHC I

presents endogenous peptides to CD8+ T cells.

MHC II

presents exogenous peptides to CD4+ T cells.

Dendritic cells

Professional APCs that migrate to secondary lymphoid tissue to prime naive T cells; part of innate immunity.

CCR7

Chemokine receptor directing migration to lymphoid tissue in response to CCL21.

CCL21

Chemokine produced by HEV endothelium that attracts CCR7-expressing cells.

HEV (high endothelial venules)

Blood vessels in lymph nodes that allow naive T and B cells to enter from blood.

Naïve T-Cells

T cells that have not yet encountered their antigen; circulate through lymphoid tissues.

originate in bone marrow

L-selectin

Adhesion molecule (CD62L) mediating tethering to endothelium via CD34 and GlyCAM-1.

CD34

Endothelial ligand for L-selectin, facilitating lymphocyte homing to lymph nodes.

GlyCAM-1

Endothelial ligand for L-selectin during entry into lymph nodes.

LFA-1

Integrin on T cells that strengthens adhesion to ICAM-1/2, aiding diapedesis.

ICAM-1/ICAM-2

Adhesion molecules that bind LFA-1 to enable firm adhesion and migration.

TCR

recognizes peptide-MHC complexes.

CD4

Co-receptor on helper T cells recognizing MHC II.

MHC II–CD4 signaling

Engagement initiates T-cell activation and transcriptional changes.

Co-stimulation

Second signal essential for full T-cell activation, usually CD28–B7 interaction.

B7-1 (CD80)

Co-stimulatory molecule on APCs engaging CD28 on T cells.

B7-2 (CD86)

Co-stimulatory molecule on APCs engaging CD28 on T cells.

CD28

T-cell receptor delivering the co-stimulatory signal by binding B7.

Anergy

T-cell functional inactivation due to lack of co-stimulation.

CD3

Component of the TCR complex that transduces activation signals.

Protein Kinase C (PKC)

Kinase involved in signal transduction during T-cell activation.

Tyrosine Kinases

Enzymes that phosphorylate signaling proteins to propagate T-cell signals.

IL-2

Autocrine growth factor promoting T-cell proliferation; supports regulatory T cells.

CD25

IL-2 receptor alpha chain; marker of activated T cells with high-affinity IL-2 receptor.

Regulatory T-cells (Tregs)

T cell subset that suppresses immune responses to maintain tolerance.

CD40L

CD40 ligand on activated helper T cells that engages CD40 on B cells and APCs.

CD40

Receptor on B cells and APCs that triggers activation upon CD40L binding.

Th1

T helper subset promoting cell-mediated immunity; IFN-γ production and macrophage activation.

Th2

T helper subset promoting humoral immunity; IL-4, IL-5, IL-13; IgE production.

Th17

T helper subset driving inflammation; IL-17 and IL-22; neutrophil recruitment.

TFH (T follicular helper cells)

T helper cells that assist B cells in germinal centers via CD40L and cytokines.

IL-12

Cytokine that promotes Th1 differentiation.

IFN-γ

activates macrophages and promotes IgG isotype switching.

IL-4

Cytokine promoting Th2 differentiation; enhances IgE class switching.

IL-5

Cytokine supporting eosinophil growth and B cell activity; linked to IgE production.

IL-13

Cytokine promoting allergic responses and IgE production.

IL-1

Pro-inflammatory cytokine promoting Th17 differentiation with IL-6.

IL-6

Pro-inflammatory cytokine aiding Th17 differentiation; promotes acute phase responses.

IL-15

Cytokine supporting memory T-cell survival and expansion.

Memory T-cells

Long-lived T cells that respond rapidly upon re-exposure to antigen.

CD40–CD40L interaction

Binding between B cells and helper T cells essential for B-cell activation and isotype switching.

B-cell activation

Process by which B cells recognize antigen and receive signals to proliferate and differentiate.

BCR (B-cell receptor)

Surface immunoglobulin that binds specific antigen to initiate signaling.

TLR (Toll-like receptor)

Pattern-recognition receptor providing innate signals to B cells and other cells.

Complement receptor

B-cell receptor for complement components aiding activation.

B7 expression

Upregulation of B7 on APCs enabling efficient T-cell co-stimulation.

Extrafollicular B-cell proliferation

Early B-cell expansion outside germinal centers after activation.

Isotype switching

Class switch of antibody heavy chain to IgG, IgA, or IgE from IgM/IgD.

Somatic hypermutation

Mutation in variable regions of immunoglobulin genes increasing affinity.

Germinal centers

Lymph node structures where B cells undergo maturation and selection.

Dark zone

GC region with rapidly dividing B cells undergoing hypermutation.

Light zone

GC region where higher-affinity B cells are selected with TFH help.

Memory B-cells

Long-lived B cells that persist for rapid response on re-exposure.

Plasma cells

Antibody-secreting B cells, often long-lived in bone marrow.

TFH help in B activation

TFH cells provide signals to B cells for germinal center maturation.

Antigen processing by B-cells

B cells internalize antigen and present peptides on MHC II to CD4+ T cells.

CD40–CD40L in B-cell differentiation

Interaction promotes B-cell maturation and class switching.

Cytokines directing isotype switching

IFN-γ promotes IgG; IL-4/IL-5/IL-13 promote IgE class switching.

IgM

First antibody isotype produced in the initial immune response.

IgD

B-cell receptor isotype co-expressed with IgM on naive B cells.

IgG

High-affinity, class-switched antibody predominant in systemic immunity.

Th1 vs Th2 outcomes

Th1 drives cell-mediated immunity and IgG; Th2 drives humoral responses and IgE.

Th1: Macrophage activation (M1)

IFN-γ from Th1 activates macrophages toward the M1 phenotype.

Th2: Eosinophils and IgE

Th2 cytokines promote eosinophil/mast cell responses and IgE production.

Th17: IL-17 and IL-22

Cytokines recruit neutrophils and monocytes; strengthen barrier defense.

IFN-γ and IgG switching

IFN-γ promotes IgG class switching in B cells.

PD-1

Programmed death-1 receptor on T cells that dampens activation when engaged.

PD-L1

Ligand on tumor and other cells that binds PD-1 to inhibit T-cell responses.

Pembrolizumab

Anti-PD-1 antibody blocking PD-1–PD-L1/PD-L2 interaction to sustain T-cell activity.

Nivolumab

Anti-PD-1 antibody used in cancer immunotherapy to enhance T-cell responses.

CTLA-4

Inhibitory receptor that downregulates T-cell responses; blockade enhances immunity.