Major histocompatibility complex matching and other factors influencing skin allograft survival in related and unrelated rhesus monkeys.

SUMMARY Skin allografting was performed in rhesus monkeys to study the influence of matching for products of the RhLA region and of various other parameters. As expected, the longest mean survival times (MSTs) were observed when donors were RhLA-identical siblings; the MST seemed a bit shorter when grafts from at least two RhLA-nonidentical siblings were simultaneously present. Matching for RhLA-A and B locus antigens was studied in RhLA-haploidentical and in unrelated combinations; in both categories, the MST was about 12 days if there were no A or B antigen disparities, 10 days if there was one A or B disparity, and about 9 days for two or more disparities. A positive effect of matching for D/DR antigens and mixed lymphocyte culture (MLC) nonresponsiveness between host and donor was questionable; additional data are required to confirm the minor beneficial effect observed. With regard to the sex of donors and recipients, female recipients rejected skin allografts more rapidly than did males in related and unrelated combinations. In this respect, females with a known or possible history of pregnancy were not different from nulliparous animals. A possible influence of donor sex on skin allograft survival remained equivocal. The i.v. administration of donor-specific antigen before skin grafting led to a significant prolongation of the MST; in the majority of combinations with prolonged graft survival, B cell-specific antibodies were demonstrable in the recipients' sera. An “enhancing” influence of such antibodies is possible, although the available data do not prove such an effect.