MHC

The Major Histocompatibility Complex (MHC) or Human Leukocyte Antigen (HLA) system, is a critical component of the immune system necessary for presenting pathogenic antigens to T cells and playing key roles in immune recognition and transplantation. The MHC gene region is on chromosome 6 in humans and encodes a set of cell surface proteins known as MHC molecules. These molecules are categorized into two main classes: MHC class I and MHC class II. MHC class I molecules are found on the surface of most nucleated cells and are involved in immune surveillance, defence against viral infections, and regulation of immune responses presenting self- or non-self-peptides to cytotoxic T cells (CD8+ T cells). They consist of a heavy chain and a smaller protein called beta-2 microglobulin. MHC Class II, in contrast are primarily found on the surface of professional antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells. They present exogenous peptide antigens, such as those from pathogens to helper T cells (CD4+ T cells) and consist of alpha and a beta chains. The MHC system is central to adaptive immunity allowing T cells to recognize and respond to antigens. Antigen presentation occurs in a series of steps: 1) antigen processing, in which antigens from pathogens (or the cell's own proteins) are proteolytically cleaved into smaller peptide fragments within the cell; 2) loading onto MHC molecules, in which for the MHC class I pathway, peptides are loaded onto MHC class I molecules in the endoplasmic reticulum, whereas for the MHC class II pathway, they are loaded onto MHC class II molecules in endosomes; 3) surface presentation, in which MHC-peptide complexes are transported to the cell surface and presented to T cells. MHC class I presents antigens to CD8+ cytotoxic T cells, whilst MHC class II presents antigens to CD4+ helper T cells. The MHC system plays several crucial roles in the immune response. Firstly, MHC-peptide complexes act as tags that allow T cells to recognize antigens and become activated. This activation leads to the differentiation of T cells into T effector cells that carry out specific immune functions. MHC molecules help distinguish self from nonself. T cells are exposed in the thymus to self-antigens and thereby to subsequently recognize them, ensuring that T cells do not attack the body's own cells. Thirdly, MHC compatibility is crucial for organ and tissue transplantation. Mismatched MHC molecules can lead to graft rejection, as host T cells recognize the transplanted tissue as foreign. Lastly, MHC molecules also play a role in regulating the immune response. Regulatory T cells, a subset of CD4+ T cells, help dampen immune reactions and prevent excessive inflammation by interacting with MHC class II molecules. An important feature of the MHC system is its high degree of genetic polymorphism. MHC genes exhibit an extensive variety of alleles in the population, resulting in a diverse array of MHC molecules. This diversity allows the immune system to recognize a wide range of antigens, contributing to the effectiveness of immune responses. We offer a comprehensive product catalogue of research reagents for studying MHC, including HLA DR + HLA DP antibodies, beta 2 Microglobulin antibodies, HLA G antibodies, Cathepsin S ELISA Kits, and beta 2 Microglobulin ELISA Kits. Explore our full MHC product range below and discover more, for less. Alternatively, you can explore our Class I and Class II product ranges.