Major Histocompatibility Complex (MHC)

These flashcards summarize key concepts, definitions, and processes related to the Major Histocompatibility Complex (MHC) and its role in immune response, providing a comprehensive study tool for understanding MHC-mediated antigen presentation.

Major Histocompatibility Complex (MHC)

A gene cluster that encodes glycoproteins involved in antigen presentation.

Antigen Presentation

The process by which antigen-presenting cells display antigen fragments on MHC molecules to T cells.

MHC Class I

MHC molecules expressed on all nucleated cells that present endogenous antigens to CD8+ T cells.

MHC Class II

MHC molecules expressed primarily on professional antigen-presenting cells (APCs) that present exogenous antigens to CD4+ T cells.

Endogenous Pathway

The antigen presentation pathway where proteins synthesized within the cell are processed and presented by MHC I.

Exogenous Pathway

The antigen presentation pathway where extracellular proteins are taken up and processed by APCs and presented by MHC II.

MHC Restriction

The requirement that only antigens bound to MHC molecules can trigger an immune response.

Heterozygote Advantage

The increased ability of heterozygous individuals to respond to a broader range of antigens due to a greater variety of MHC alleles.

Polymorphism

The presence of multiple alleles at a gene locus, leading to variation in MHC molecules.

TAP (Transporter for Antigen Processing)

A protein that transports peptides from the cytosol into the endoplasmic reticulum for loading onto MHC I.

Invariant Chain

A protein that stabilizes MHC II during its transport to the endosomal compartment before it binds antigen.

CLIP (Class II-associated invariant chain peptide)

A fragment of the invariant chain that occupies the binding groove of MHC II until it is replaced by a peptide.

MHC Class III

A class of MHC molecules that encodes complement proteins and other molecules important in the immune response.

Cytotoxic T Cells

T cells that are activated by MHC I molecules presenting endogenous antigens, leading to the killing of infected cells.

Helper T Cells

T cells that interact with MHC II molecules on APCs to provide help in the immune response.

Antigen-Presenting Cells (APCs)

Cells that process and present antigens via MHC molecules, including dendritic cells, macrophages, and B cells.