What are human leukocyte antigens?

Diseases are constantly taking away human health. We don’t know when and under what circumstances we will suffer from some unpredictable diseases. All we can do now is to learn more about the knowledge of diseases. Knowledge is not only useful to yourself. Sometimes when others don’t understand something, you can help explain it to them. Let us now learn about human leukocyte antigens and pay attention to the health of ourselves and those around us.

Human leukocyte antigen, in English, is human leukocyte antigen, abbreviated as HLA. It is the human major histocompatibility complex (MHC), located on chromosome 6 (6p21.31), and includes a series of tightly linked loci that are closely related to the human immune system function. Some of these genes encode cell surface antigens, which become the unmistakable "signatures" of each person's cells and are the basis for the immune system to distinguish between its own and foreign substances.

Human leukocyte antigen type 1 consists of an alpha chain that spans the cell membrane and an extracellular beta-2 microglobulin attached to this chain. The entire molecule consists of four regions, three of which are located on the α chain (α1-α3) and the β2 microglobulin constitutes the fourth region. The parts of the molecule that lie outside the cell (α1 and α2) form a pit into which the peptide can stick. The peptides that stick here are generally fragments of proteins that have been dismantled in the proteasome. Immune cells (such as CD8+-T cells) can examine these peptides stuck on the cell surface to distinguish between self and foreign cells. All cells in the body that contain a nucleus have human leukocyte antigen type 1, which is further subdivided into HLA-A, HLA-B and HLA-C.

HLA-2 consists of an α chain and a β chain, both of which pass through the entire cell membrane. Outside the cell, this molecule has four regions (α1, α2, β1, and β2), of which α1 and β1 form a pit. HLA-2 is slightly larger than HLA-1. Only phagocytic cells (such as macrophages) have HLA-2 on their surface. Peptides from proteins broken down by lysosomes during macrophagy are stuck in HLA-II pits. This type of molecule can be further divided into HLA-DP, HLA-DQ, HLA-DR, HLA-DN and HLA-DO.

The difference between the third type of human leukocytes and the first two types is that the third type of human leukocyte antigen is a molecule in the extracellular matrix and it participates in indiscriminate immunity. It can be divided into HLA-C2, HLA-C4 and HLA-Bf.

Health has become a topic that people pay more and more attention to. Various health-preserving methods and nutritional diet therapies are actually for the purpose of making the body healthier. Therefore, for the sake of health, we should accumulate more relevant knowledge, understand human leukocyte antigens, pay attention to all aspects of life, and provide more rational protection for ourselves and our families, so that the clarion call for safety and health will become louder and louder.