Generation of donor-specific T regulatory type 1 cells from patients on dialysis for cell therapy after kidney transplantation

Background. Tregulatory type 1 (Tr1) cell-mediated induction of tolerance in preclinicalmodels of transplantation is remarkably effective. The clinical application of such a therapy in patients on dialysis undergoing kidney transplantation should take into account the possible alterations of the immune systemobserved in these patients. Herein, we aimed at testing the ability to generate donor-specific Tr1 cell-enriched lymphocytes from patients on dialysis on the waiting list for kidney transplantation. Methods. The Tr1 cell-enriched lymphocytes were generated by coculturing interleukin-10-producing dendritic cells obtained from healthy donors with peripheral bloodmononuclear cells (PBMCs) of patients on dialysis, following the same protocol used in a previous cell therapy clinical trial to prevent graft-versus-host disease. Alternatively, purified CD4+ Tcells were used instead of total PBMCs. The ability to generate clinical-grade Tr1 cell-enriched products was defined by testing the reduced response to restimulation withmature dendritic cells generated fromthe original donor (i.e., anergy assay). Results. The Tr1 cell-enrichedmedicinal products generated from PBMCs of patients on dialysis showed a low anergic phenotype, incompatible with their eventual clinical application. This was irrespective of HLA matching with the donor or the intrinsically reduced ability to proliferate in response to alloantigens. On the contrary, the use of purified CD4+ T cells isolated from patients on dialysis led to the generation of a highly anergic donor-specific medicinal product containing an average of 10% Tr1 cells. Conclusions. The Tr1 cell-enriched medicinal products can be efficiently generated from patients on dialysis by carefully tailoring the protocol on the patients' immunological characteristics.