Skin-derived γδ T cells as a source of IL-17 in the lymph nodes and a possible initiator in contact hypersensitivity (121.22)

Abstract

Abstract In the murine skin, there exist two subsets of γδ T cells, Vγ5+ dendritic epidermal T cells (DETCs) and Vγ4+ dermal γδ T cells. It remains unclarified about the role of skin γδ T cells in contact hypersensitivity and their homeostasis. Initially, to evaluate the mobility of cutaneous γδ T cells, we used kaede-transgenic mice which express photoconvertible fluorescence protein “kaede”. By exposing the skin to violet light, cutaneous cells changes its fluorescence from green to red. Using this labeling system, we demonstrated that γδ T cells migrated from the skin to draining lymph nodes (DLNs) even in the steady state and such transmigration was enhanced after hapten-application. Skin-derived γδ T cells were mainly Vγ4+ cells, suggesting that they were dermal origin. In addition, this subset produced a higher amount of IL-17 than either LN-resident γδ T cells or αβ T cells migrating from the skin. In addition, we found that γδ T cells assisted αβ T cells proliferation and production of IFN-γ and IL-17 in vitro. These data suggest that the main source of IL-17 in the DLN is γδ T cells from the dermis, and this population may play an important role to establish contact hypersensitivity response through modulating αβ T cell functions.