BIO444 MHC Processing

Innate Immune System

The part of the immune system that recognizes pathogens through Pattern Recognition Receptors (PRRs) that detect Pathogen-Associated Molecular Patterns (PAMPs) and Damage-Associated Molecular Patterns (DAMPs).

Adaptive Immune System

The part of the immune system that involves lymphocytes (B and T cells) which recognize specific antigens.

Antigen

Any substance that triggers an adaptive immune response in the body.

T-Cell Receptor (TCR)

A receptor on T cells that recognizes protein fragments (peptides) presented by Major Histocompatibility Complex (MHC) molecules.

B-Cell Receptor (BCR)

A receptor on B cells that recognizes specific antigens directly.

Antigen Presentation

The process by which cells present protein fragments to T cells using MHC proteins.

Major Histocompatibility Complex (MHC)

A set of membrane glycoproteins that display peptide antigens on antigen-presenting cells (APCs) for recognition by T lymphocytes.

MHC Class I

A class of MHC molecules that presents intracellular antigen peptides to CD8+ T cells and is found on all nucleated cells.

MHC Class II

A class of MHC molecules that presents extracellular antigen peptides to CD4+ T cells and is found on professional antigen-presenting cells (APCs) like dendritic cells, macrophages, and B cells.

Polymorphism

The presence of multiple alleles (variants) of MHC genes in the population, contributing to the diversity of immune responses.

Antigen-Presenting Cells (APCs)

Cells that process and present antigens to T cells, including dendritic cells, macrophages, and B cells.

Proteasome

A protein complex that degrades intracellular proteins into short peptides for presentation by MHC class I molecules.

Transporter Associated with Antigen Processing (TAP)

A protein complex that transports cytosolic peptides into the endoplasmic reticulum for loading onto MHC class I molecules.

CD4+ T Cells

Also known as T helper cells, these T cells assist other immune cells by presenting antigens and releasing cytokines.

CD8+ T Cells

Also known as T cytotoxic cells, these T cells directly kill infected or cancerous cells.

Immunoproteasome

A specialized form of the proteasome found in professional APCs that cleaves proteins into small fragments specifically for MHC class I presentation.

Phagocytosis

The process by which APCs ingest extracellular microbes or proteins for processing and presentation.

HLA (Human Leukocyte Antigen)

Another name for MHC molecules, particularly in humans, involved in immune response and graft rejection.

Co-dominant Expression

The phenomenon where alleles inherited from both parents are expressed equally, maximizing the diversity of MHC proteins in an individual.