The Major Histocompatibility Complex (MHC) refers to a genetic system found in vertebrates, particularly in humans, that plays a crucial role in the immune response to foreign substances in the body. It is a highly complex region located on chromosome 6 in humans, containing a cluster of genes responsible for coding proteins known as human leukocyte antigens (HLAs).
HLAs are crucial in determining an individual's immune response as they help distinguish self from non-self cells. These proteins are present on the surface of almost all cells in the body, serving as markers that allow immune cells to recognize and bind to foreign antigens, such as pathogens or molecules from transplanted organs.
The MHC is divided into three main regions: class I, class II, and class III. Class I genes encode proteins found on the surface of almost all nucleated cells, enabling the immune system to detect and destroy infected or abnormal cells. Class II genes, primarily expressed on immune system cells like B cells, dendritic cells, and macrophages, contribute to the presentation of antigens to helper T cells, crucial for an effective immune response. Class III genes are involved in various immune functions, including the production of proteins with anti-inflammatory properties.
The polymorphic nature of MHC genes contributes to the remarkable diversity of the immune system among individuals. Variations in MHC genes are associated with the susceptibility or resistance to certain diseases, including autoimmune disorders, infectious diseases, and transplant rejection. Understanding the MHC and its significance is essential for studying immunogenetics, disease susceptibility, and the development of personalized medicine approaches.
