Major histocompatibility complex
The major histocompatibility complex (MHC) is a multigene region in jawed vertebrates that encodes cell-surface glycoproteins central to antigen presentation and T-cell recognition. In humans, the MHC is termed the Human Leukocyte Antigen (HLA) system and resides on chromosome 6p21, encompassing class I, class II, and class III gene clusters that govern adaptive immunity, natural killer cell regulation, and complement components. Extensive polymorphism across classical HLA loci underlies interindividual variation in immune responses, disease associations, and transplantation compatibility.
