Major Histocompatibility Complex

**Definition:** The genetic region which contains the loci of genes which determine the structure of the serologically defined (SD) and lymphocyte-defined (LD) TRANSPLANTATION ANTIGENS, genes which control the structure of the IMMUNE RESPONSE-ASSOCIATED ANTIGENS, HUMAN; the IMMUNE RESPONSE GENES which control the ability of an animal to respond immunologically to antigenic stimuli, and genes which determine the structure and/or level of the first four components of complement.

**Tree numbers:** - G05.360.340.024.340.610 - G05.360.340.024.380.500 - G12.500.500

**Synonyms:** - Histocompatibility Complex