Graft-versus-host disease (GVHD) is driven by extensive activation and proliferation of alloreactive donor T cells causing significant morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). Invariant natural killer T (iNKT) cells are a potent immunoregulatory T-cell subset in both humans and mice. Here, we explored the role of adoptively transferred third party CD4(+) iNKT cells for protection from lethal GVHD in a murine model of allogeneic HCT across major histocompatibility barriers. We found that low numbers of CD4(+) iNKT cells from third party mice resulted in a significant survival benefit with retained graft-versus-tumor (GVT) effects. In vivo expansion of alloreactive T cells was diminished while displaying a Th2-biased phenotype. Notably, CD4(+) iNKT cells from third party mice were as protective as CD4(+) iNKT cells from donor mice although third party CD4(+) iNKT cells were rejected early after allogeneic HCT. Adoptive transfer of third party CD4(+) iNKT cells resulted in a robust expansion of donor CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) that were required for protection from lethal GVHD. However, in vivo depletion of myeloid-derived suppressor cells (MDSCs) abrogated both Treg expansion and protection from lethal GVHD. Despite the fact that iNKT cells are a rare cell population, the almost unlimited third party availability and feasibility of in vitro expansion provide the basis for clinical translation.
View details for DOI 10.1182/blood-2014-11-612762
View details for PubMedID 25795920