What does it mean to have an antigen presented?

Antigen presentation is the expression of antigen molecules on the surface of a macrophage or other antigen-presenting cell in association with MHC class II molecules when the antigen is being presented to a CD4+ helper T cell or in association with MHC class I molecules when presentation is to CD8+ cytotoxic T cells.

What are major histocompatibility complex antigens?

major histocompatibility complex (MHC), group of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances. MHC proteins are found in all higher vertebrates. In human beings the complex is also called the human leukocyte antigen (HLA) system.

What are antigen presenting cells and why are they important?

An antigen-presenting cell (APC) is an immune cell that detects, engulfs, and informs the adaptive immune response about an infection. When a pathogen is detected, these APCs will phagocytose the pathogen and digest it to form many different fragments of the antigen. Macrophages also function as APCs.

What is antigen presentation and why is it critical during an immune response?

Antigen presentation is a process in the body’s immune system by which macrophages, dendritic cells and other cell types capture antigens, then present them to naive T-cells. The basis of adaptive immunity lies in the capacity of immune cells to distinguish between the body’s own cells and infectious pathogens.

What is HLA antigen?

A type of molecule found on the surface of most cells in the body. Human leukocyte antigens play an important part in the body’s immune response to foreign substances. They make up a person’s tissue type, which varies from person to person.

Is CD8 an antigen?

Antigen CD8 T cells can form stable conjugates with CD4 T cells and this interaction can lead to amplification of the CD8 T cell response (Chaudhri et al., 2009).

What is a CD8 T cell?

Definition. CD8-positive T cells are a critical subpopulation of MHC class I-restricted T cell and are mediators of adaptive immunity. They include cytotoxic T cells, which are important for killing cancerous or virally infected cells, and CD8-positive suppressor T cells, which restrain certain types of immune response …

Where does antigen presentation occur?

Large complexes of intact antigen are presented in lymph nodes to B cells by follicular dendritic cells in the form of immune complexes. Some APCs expressing comparatively lower levels of lysosomal enzymes are thus less likely to digest the antigen they have captured before presenting it to B cells.