Cutting Edge: Identification of a Motile IL-17-Producing γδ T Cell Population in the Dermis

Dendritic epidermal T cells (DETCs) are a well-studied population of gamma delta T cells that play important roles in wound repair. In this study, we characterize a second major population of gamma delta T cells in the skin that is present in the dermis. In contrast to DETCs, these V gamma 5-negative cells are IL-7R(hi)CCR6(hi) retinoic acid-related orphan receptor gamma t(+) and are precommitted to IL-17 production. Dermal gamma delta T cells fail to reconstitute following irradiation and bone marrow transplantation unless the mice also receive a transfer of neonatal thymocytes. Real-time intravital imaging of CXCR6(GFP-/+) mouse skin reveals dermal gamma delta T cells migrate at similar to 4 mu m/min, whereas DETCs are immobile. Like their counterparts in peripheral lymph nodes, dermal gamma delta T cells rapidly produce IL-17 following exposure to IL-1 beta plus IL-23. We have characterized a major population of skin gamma delta T cells and propose that these cells are a key source of IL-17 in the early hours after skin infection. The Journal of Immunology, 2011, 186: 6091-6095.