2.1 Adaptive Immune Response Vocabulary

Vocabulary flashcards covering key terms from the lecture notes on the adaptive immune response, antigen presentation, DCs, and co-stimulation.

Antigen

Any molecule or molecular fragment recognized by antibodies or B-cell receptors or bound by an MHC molecule and presented to a T-cell receptor.

Antigen receptor

Lymphocyte surface receptor that recognizes an antigen (BCR or TCR).

B cell receptor (BCR)

Cell-surface immunoglobulin on B cells that binds antigen and defines B-cell specificity.

T cell receptor (TCR)

Receptor on T cells that recognizes antigenic peptides bound to MHC on APCs.

Naïve T-cell

T cell that has not yet engaged in an immune response.

Effector T-cell

Activated T cell capable of mounting an immune response; results from differentiation after activation.

Dendritic cell (DC)

Professional APC that presents antigens to T cells, provides co-stimulation, and matures via PRR signaling.

Langerhans cell

Dendritic cells located in the skin.

MHC class I

MHC molecule that presents endogenous peptides to CD8+ cytotoxic T cells.

MHC class II

MHC molecule that presents exogenous peptides to CD4+ helper T cells.

Co-stimulation

Second signal required for full T-cell activation, e.g., B7 on APC engaging CD28 on T cells.

B7

Co-stimulatory molecule expressed by mature APCs that binds CD28 on T cells.

CD28

Co-stimulatory receptor on T cells that binds B7.

TLR (Toll-like receptor)

Pattern recognition receptor that detects PAMPs and activates innate signals that help mature DCs.

PRR (Pattern Recognition Receptor)

Receptors that detect pathogen-associated or danger signals to initiate innate responses.

NF-κB

Transcription factor activated downstream of PRR signaling; promotes inflammatory gene expression and B7 upregulation.

Clonal expansion

Proliferation of activated T cells to generate many antigen-specific effector cells.

Humoral immunity

Antibody-mediated immunity produced by B cells.

Antigen presentation

Process by which protein antigens are processed into short peptides and displayed on MHC molecules on APCs.

Antigen-presenting cell (APC)

Cell such as a dendritic cell, macrophage, or B cell that presents antigens to T cells via MHC.

Hapten

Small molecule that elicits an antibody response only when bound to a carrier protein.

Immunological memory

The ability of the adaptive immune system to respond more rapidly and effectively upon repeated exposure to antigen.

Helper T-cells

Provide assistance to other cells in the immune response (especially B cells)

Regulatory T-cells

limit excessive or undesired immune responses

Cytotoxic T-cells

Kill human body cells infected with pathogens