Patterns of Immune Regulation in Rhesus Macaque and Human Families

Naturally acquired immune regulation amongst family members can result in mutual regulation between living related renal transplant donor and recipients. Pretransplant bidirectional regulation predisposed to superior renal allograft outcome in a CAMPATH-1H protocol. We tested whether Rhesus macaques, a large animal model of choice for preclinical transplant studies, share these immunoregulatory properties. METHODS: Antigen-specific linked suppression was measured by trans vivo delayed-type hypersensitivity [tvDTH] response. Neutralizing antibodies to regulatory cytokines, IL-10, TGF-β, and IL-35 were coinjected to ascertain the role of these cytokines in the regulatory response. RESULTS: Peripheral blood mononuclear cells (PBMC) of 116 Rhesus macaques in 50 families and 78 human subjects in 25 families were analyzed. Suppression of the recall response of 25% or greater was detected in 30 of 51 (59%) monkeys, and 25 of 36 (69%) human subjects when PBMC were coinjected with antigens of the mother, containing the noninherited maternal antigens. In 33% of Rhesus and 32% of human subjects, linked suppression was also seen when PBMC from the mother was assayed with antigens from offspring. Bidirectional regulation was also seen between greater than 50% of the major histocompatibility complex (MHC)-identical full siblings; subcellular antigens caused significant linked suppression in 7 of 10 (Rhesus) and 8 of 15 (human) cases, indicating the importance of familial minor H antigens. The lowest incidence of regulation was seen in MHC-1 haplotype mismatched siblings in both species. Linked suppression was most effectively reversed by antibodies that neutralized TGFβ1, and the 2 subunits of IL-35 (Ebi3 and IL12p35). CONCLUSIONS: Rhesus macaques provide a suitable model for analyzing the impact of bidirectional regulation in living related donor-recipient pairs.