H antigen
H antigen can refer to one of the various types of antigens having diverse biological functions:
- Also known as substance H, H antigen is a precursor to each of the ABO blood group antigens, apparently present in all people except those with the Bombay Blood phenotype. The gene responsible for making H antigen is FUT1, located on the 19th chromosome in humans.
- Histocompatibility antigen, a major factor in graft rejection.
- * major H antigens "encode molecules that present foreign peptides to T cells"
- * minor H antigens are polymorphic alloantigens presented on foreign major histocompatibility complex molecules. Includes, e.g. the H-Y antigen. Even when major histocompatibility complex genotype is perfectly matched, can cause slow rejection of a graft.
- a bacterial flagellar antigen