Evolution and Diversity of the Human Leukocyte Antigen(HLA)

Human leukocyte antigen (HLA) Class I and Class II antigens can be genetically extremely diverse, play a central role in immunity and are of primary importance in several branches of medicine. By presenting fragments of pathogens or altered ‘self’ proteins, HLA molecules activate T lymphocytes and are essential in adaptive immune responses against infection or cancer. Clinically, certain HLA types are associated with severity, treatment outcomes or risk of particular infections (e.g. HIV, leprosy, hepatitis B virus) [1]. HLA are the most important histocompatibility antigens to match donors and recipients for successful organ or tissue transplantations. They are also the strongest known predictors of a range of autoimmune disorders including Type I diabetes, coeliac disease, narcolepsy and spondyloarthritis [2]. Increasing evidence also suggests that the combination of HLA types in a couple might affect fertility [3].