Monocytic myeloid-derived suppressor cells generated from rhesus macaque bone marrow enrich for regulatory T cells.

Putative monocytic myeloid-derived suppressor cells (mMDSC; lineage- HLA-DR-/lo ) were generated in 7-day cultures from normal rhesus macaque bone marrow (BM) cells in GM-CSF and IL-6. Three subsets were identified based on their differential expression of CD14, CD33, CD34 and CD11b. Following flow sorting, assessment of the capacity of these subsets to suppress anti-CD3/CD28-stimulated CD4 and CD8 T cell proliferation revealed that the most potent population was CD14hi CD33-/lo CD34lo CD11bhi . These BM-derived mMDSC markedly increased the incidence of CD4+ CD25+ CD127- Foxp3+ regulatory T cells in responder T cell populations. They offer potential value in testing the therapeutic efficacy of immunoregulatory mMDSC for the promotion of tolerance in nonhuman primate transplant models.