MHCantigén

MHCantigén, also known as Major Histocompatibility Complex (MHC) antigen, is a type of protein found on the surface of cells that plays a crucial role in the immune system's ability to recognize and respond to foreign substances, such as viruses and bacteria. MHC antigens are encoded by the MHC genes, which are located on chromosome 6 in humans. There are two main classes of MHC antigens: MHC class I and MHC class II.

MHC class I antigens are expressed on all nucleated cells and present endogenous antigens, which are proteins produced within the cell, to CD8+ T cells. This interaction helps the immune system to identify and eliminate infected cells.

MHC class II antigens are primarily expressed on antigen-presenting cells, such as dendritic cells and macrophages, and present exogenous antigens, which are proteins taken up by the cell from the outside environment, to CD4+ T cells. This interaction is essential for the activation of the adaptive immune response.

MHC antigens are highly polymorphic, meaning they vary greatly among individuals. This polymorphism is important for the functioning of the immune system, as it allows the body to recognize and respond to a wide range of pathogens. However, it can also lead to compatibility issues in organ transplantation, as mismatches in MHC antigens can result in rejection of the transplanted organ.

In summary, MHCantigéns are essential proteins in the immune system that help to recognize and respond to foreign substances. Their polymorphism is crucial for immune function but can also present challenges in medical contexts such as organ transplantation.