Infusion of clinical‐grade enriched regulatory T cells delays experimental xenogeneic graft‐versus‐host disease

Abstract

Background We investigated the ability of clinical‐grade enriched human regulatory T cells (Treg) to attenuate experimental xenogeneic graft‐versus‐host disease (GVHD) induced by peripheral blood mononuclear cells (PBMNCs; autologous to Treg) infusion in NSG mice, as well as verified their inability to induce xenogeneic GVHD when infused alone. Study Design and Methods Human Treg were isolated from peripheral blood apheresis products with a cell separation system (CliniMACS, Miltenyi Biotec GmbH) using a two‐step procedure (simultaneous CD8 and CD19 depletion followed by CD25‐positive selection) in six independent experiments with six different healthy volunteer donors. Sublethally (2.5 Gy) irradiated NSG mice were given 2 × 106 cytapheresis (PBMNC) product cells intravenously (IV) without (PBMNC group) or with 1 × 106 Treg (PBMNC + Treg group), while other NSG mice received 2 × 106 enriched Treg alone (also in IV; Treg group). Results The first five procedures were successful at obtaining a relatively pure Treg population (defined as >50%), while the sixth procedure, due to a technical problem, was not (Treg purity, 42%). Treg cotransfusion significantly delayed death from xenogeneic GVHD in the first five experiments, (p < 0.0001) but not in the sixth experiment. Importantly, none of the mice given enriched Treg alone (Treg group) experienced clinical signs of GVHD, while, interestingly, the CD4+ cells found in these mice 26 days after transplantation were mainly conventional T cells (median CD25+FoxP3+ cells among human CD4+ total cells were only 2.1, 3.1, and 12.2% in spleen, marrow, and blood, respectively). Conclusions Infusion of clinical‐grade enriched Treg delayed the occurrence of xenogeneic GVHD without inducing toxicity in this murine model.

Cellular immunotherapy in multiple myeloma: Lessons from preclinical models

“…In addition, lethal xenogeneic GvHD was observed. Co-infusion of Tregs inhibited lethal xenogeneic GvHD, as observed by other groups of investigators [86], and did not impair the GvM response against myeloma residing in the bone marrow. However, it did impair anti-tumor responses against myeloma growing outside of the bone marrow.…”

Anti-thymocyte globulin as graft- versus -host disease prevention in the setting of allogeneic peripheral blood stem cell transplantation: a review from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

“…[31][32][33] This is clinically relevant given accumulating evidence showing an important role for Treg in GvHD prevention after allogeneic HCT. [34][35][36][37] The next paragraphs review the impact of both forms of rabbit ATG on transplantation outcomes in various transplantation settings. However since there has been no controlled head-to-head comparison between ATG-T and ATG-F reported thus far in the allogeneic HCT setting, one should be cautious when extrapolating data from medical literature referring to one of these two drugs.…”

Novel approaches for preventing acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

“…[34,35] Tregs are also featured by a dependency on IL-2 for their homeostasis. [35,36] Importantly, several studies have demonstrated that Treg cotransplantation at a Treg/CD4 + Tconv ratio of 1/1 or 1/2 prevented aGVHD in mouse to mouse [37,38] as well as in humanized mice [39,40] [50] In mice, the B-cell protective activity appears to be mediated by their secretion of IL-10. Recently, impairment in IL-10-producing B cells (regulatory B cells, Breg) was also described in patients with cGVHD.…”

“…[37,39] Based on these observations, Treg infusion has been evaluated in the clinical setting. Specifically, safety and efficacy of Treg infusions were evaluated in a phase I clinical trial including 23 patients given double UCB-alloHSCT.…”

“…This is partly due to differences between human and murine immune systems, and more importantly, to the large genetic diversity within the human species in contrast to what is present in inbred mice. Recent developments in humanized models of GVHD may provide additional tool for testing new immunoregulatory approaches on human immune cells in vivo and offers the possibility to assess various donors with different genetic background, [39,40,49] while the canine model of unrelated dog-leukocyte antigen-mismatched transplantation has remained the only animal model that allows direct translation to the clinic. [55] The holy grail of GVHD prophylaxis is to efficiently prevent grade >1 aGVHD without compromising post-transplant immune recovery and graft-versus-tumor effects.…”