major histocompatibility complex

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A group of genes that code for cell-surface histocompatibility antigens and are the principal determinants of tissue type and transplant compatibility.

The genetic region that contains the loci of genes that determine the structure of the serologically defined (SD) and lymphocyte-defined (LD) transplantation antigens, genes that control the structure of the immune response-associated (Ia) antigens, and the immune response (Ir) genes that control the ability of an animal to respond immunologically to antigenic stimuli.

(Abbr. MHC) A chromosomal segment that codes for cell-surface histocompatibility antigens and is the principal determinant of tissue type and transplant compatibility. Also called HLA complex.

Major histocompatibility complex.