Patterns of Immune Regulation in Rhesus Macaque and Human Families.

UNLABELLED: 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.