What is "human leukocyte antigen"?

Human leukocyte antigen (HLA) refers to a group of proteins present on the surface of cells that play a crucial role in the immune system. They are responsible for distinguishing the body's own cells from foreign substances, aiding in immune responses, and regulating the compatibility of organ transplantation. HLA proteins are highly diverse and contribute to individual variations in immune responses and susceptibility to certain diseases.