Migratory properties of skin-resident γδ T cell populations (49.20)

Abstract

Abstract γδ T cells preferentially reside in epithelial tissues like skin. Dendritic epidermal T cells (DETC) in epidermis have been studied extensively. Recently, a novel IL-17-producing γδ T cell population in dermis was identified and demonstrated to have pivotal role in skin inflammation. Nevertheless, their migration patterns are largely undefined. In this study, we found that almost 30% γδ T cells in dermis, lymph nodes (LNs) and spleen are Vγ2+. This proportional distribution led us to hypothesize that γδ T cells may re-circulate between dermis and secondary lymphoid tissues. To test this hypothesis, we created GFP+:GFP- parabiotic mice, and demonstrated that dermal γδ T cells are constantly circulating, whereas DETC are stationary and non-recirculating. We next focused on skin homing of dermal γδ T cells and found that these γδ T cells were not diminished in lymphotoxin α-/- mice (lacking LNs), suggesting that dermal γδ T cells can be stably maintained after seeding from perinatal thymus. Further study revealed that dermal γδ T cells express high levels of CD69, CD103, and E- and P-selectin ligands, all of which are required for mature T cell migration to skin. However, in E- and P-selectin ligand-deficient (Fuc T IV/VII-/-) mice, dermal γδ T cells are paradoxically increased, while DETC are remarkably diminished. Taken together, these findings may help better define the role of γδ T cells in peripheral epithelial tissues.