The major histocompatibility complex of the cynomolgus monkey: absorption analysis of 24 CyLA antisera

The major histocompatibility complex (MHC) of the cynomolgus monkey consists of at least 35 serologically defined specificities, 14 of which have been assigned to the CyLA-A locus, 10 to the B locus, and six to the newly identified C locus. Selected specificities and antisera were further studied by the analysis of data obtained from absorptions with single donor platelets of known CyLA type. These data confirmed the existence of four groups of cross-reactive specificities identified by serological typing and revealed that three other well-defined specificities could be divided into two or more subtypes. Seven sera were shown to contain two or more populations of distinct, probably noncross-reactive antibodies that could be readily separated by absorption. Of the 24 sera analyzed, only three could be considered likely to contain antibodies reactive with a single CyLA specificity. At least three antibody specificities, after repeated absorption attempts, could not be readily removed by platelets and may reflect poor expression of the determinants on the platelet membrane. The complexity and degree of polymorphism of the CyLA system approaches that known for the human HLA complex. This homology of genetic organization and serologic features provide additional evidence in yet another species for the important role that these systems of alloantigens play in the organism.