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