Adaptive Immune Responses Flashcards

Vocabulary flashcards based on lecture notes about Adaptive Immune Responses.

Immunogen

Molecule capable of eliciting an immune response, typically carbohydrate or protein.

Antigen

Molecules recognized by antibodies or T-cell receptors (TCR).

Epitope

Specific region of an antigen recognized by an antibody; also called an antigenic determinant.

Hapten

Molecules too small to elicit an antibody response on its own but can generate specific antibodies when attached to a carrier molecule.

Dendritic Cells

Required to initiate an adaptive immune response and activate naïve T-cells.

T-cell Receptor (TCR)

Surface protein on T-cells that recognize antigen/MHC combinations.

CD4

Surface protein on T helper cells (TH) that recognizes MHC class II.

CD8

Surface protein on Cytotoxic T lymphocytes (CTL) that recognizes MHC class I.

MHC Class I

Major histocompatibility complex class I, displayed on all nucleated cell types presenting endogenous antigen.

MHC Class II

Major histocompatibility complex class II, displayed on APCs (macrophages, dendritic cells, and B-cells) presenting exogenous antigen to T-cells.

TH1 Response

T helper 1 response initiated by IL-12, induced against virus and bacterial infections.

TH2 Response

T helper 2 response initiated by IL-4, involved in allergic responses and increases antibody production.

Cross-presentation

Ability of dendritic cells (DCs) to present exogenous antigen on MHC class I to activate naïve CD8 T-cells (CTLs).

Granzymes and Perforin

Secreted by CTLs to induce cell death in target cells; perforin forms a membrane pore.

B-cells

Differentiate into plasma cells that produce antibodies; express BCR (immunoglobulin) on the surface.

Antibodies (Immunoglobulins)

Large globular proteins composed of heavy and light chains, with variable regions for antigen binding and constant regions (Fc) that interact with Fc receptors.

Opsonin

Molecule that enhances phagocytosis by marking an antigen for an immune response.

IgG

Major (80%) immunoglobulin in body fluids.

IgM

First antibody to appear upon infection, good agglutinator of bacteria.

IgA

Secreted antibody found on mucosal surfaces.

T-independent Pathway

B-cell activation that requires special signals, such as large repetitive antigens and ligation of PAMP receptors.

T-dependent Pathway

B-cell activation that occurs via helper T-cells that recognize the same antigen; termed “linked recognition”.

Plasma Cells

Differentiated B-cells that produce antibody.

Memory Cells

Produce low levels of antibody and quickly become plasma cells when needed

Active Immunity

Antibodies or activated lymphocytes are produced as a result of infection

Passive Immunity

Antibodies are passed to a fetus through the placenta or in the colostrum