CD49a Regulates Cutaneous Resident Memory CD8 T Cell Persistence and Response.

CD8 tissue-resident memory T cells (T) persist at sites of previous infection, where they provide rapid local protection against pathogen challenge. CD8 T expressing the α1 chain (CD49a) of integrin VLA-1 have been identified within sites of resolved skin infection and in vitiligo lesions. We demonstrate that CD49a is expressed early following T cell activation in vivo, and TGF-β and IL-12 induce CD49a expression by CD8 T cells in vitro. Despite this rapid expression, CD49a is not required for the generation of a primary CD8 T cell response to cutaneous herpes simplex virus (HSV) infection, migration of CD8 T cells across the epidermal basement membrane, or positioning of T within basal epidermis. Rather, CD49a supports CD8 T persistence within skin, regulates epidermal CD8 T dendritic extensions, and increases the frequency of IFN-γ CD8 T following local antigen challenge. Our results suggest that CD49a promotes optimal cutaneous CD8 T-mediated immunity.