A subset of Vγ4+ γδ T cells are derived from the adult murine thymus (P4462)

Abstract

Abstract γδ T cells are a phenotypically diverse subset of immune cells with equally diverse functions in innate and adaptive immunity. We have identified a population of Vγ4+ γδ T cells that play an important role in protective immunity against oral Listeria infection. To further examine these cells, we generated mixed chimeras using a combination of neonatal thymocytes (neoThy) and adult bone marrow (BM). Surprisingly, the Vγ4+ population (identified as lacking expression of all other known γδ TCRs) was derived from both neoThy and BM progenitors demonstrating that the development of Vγ4 cells is not strictly limited to early ontogeny. Indeed, Vγ4 cells were found in the adult murine thymus, and, similar to other subsets of BM-derived γδ T cells, were the progeny of c-kit+ early thymic progenitors and required an adult thymus for their development. However, unlike the neoThy-derived subset, the BM-derived Vγ4 cells had a CD44intCD27+CD25- phenotype and did not produce IL-17 in naïve mice. However, when challenged with oral Listeria, there was a significant increase in BM-derived Vγ4 cells producing both IL-17 and IFNγ, but the overall contribution of this population to the anti-Listeria response was not significant compared to that of the neoThy-derived cells. Thus, we have discovered a unique population of Vγ4-expressing γδ T cells that emerge in adulthood.