Visualizing skin γδ T cell antigen expression during wound repair

Abstract

Skin is the largest organ through which we experience the outside world and our first line of defense against environmental and pathogenic assault. Within the skin, dendritic epidermal T cells (DETC) are uniquely poised to monitor the tissue for damage and disease and play key roles in wound repair and homeostasis. Central to the role in wound repair is stimulation of the DETC through their invariant γδ TCR by an unknown antigen expressed on stressed keratinocytes. Characterizing ligands for the DETC TCR is crucial to understanding DETC activation and function. We developed soluble DETC TCR tetramers to investigate expression patterns and kinetics of putative antigens specific for the DETC TCR. In vitro tetramer studies showed stimulatory keratinocyte cell lines express DETC TCR ligands. Ex vivo tetramer staining in wounded epidermal sheets revealed rapid upregulation of antigen on keratinocytes at, but not distal to, the wound site prior to DETC activation followed by a loss of antigen after DETC activation. This study represents the first visualization of DETC antigen expression during wound repair and provides novel information about patterns of antigen expression and early stages of DETC activation during wound repair. Ongoing studies using the DETC TCR tetramer are focused upon identification of the unknown DETC antigen. This work is supported by NIH grants AI064811 to W.L.H, A142267 to L.T, and a NSF GRFP to H.K.K.