Characterization of T cell receptors on resident murine dendritic epidermal T cells

Cell lines derived from Thy‐1 dendritic epidermal cells (Thy‐1DEC) display a marked heterogeneity in T cell receptor (TcR) expression including CD3‐associated α/β, Cγ2/δ or Cγ2/δ and Cγ4/δ TcR. In order to investigate whether this heterogeneity is primarily imposed by in vitro culture conditions or, alternatively, is already present within the epidermis, we studied TcR expression by Thy‐1 DEC in situ and on freshly isolated epidermal cell suspensions greatly enriched for Thy‐1DEC. Immunolabeling experiments showed that resident Thy‐lDEC are CD45, Thy‐l, CD3, TcR V_β8⁻, CD5⁻, CD4⁻ CD8⁻, CD25⁻ lymphocytes. Immunoprecipitation of lysates from ¹²⁵1‐surface‐labeled Thy‐1DEC‐enriched epidermal cells with anti‐CD3 ε, anti‐C_γ 1,2,3 and anti‐C_γ4 antibodies, respectively, and subsequent analysis of the precipitates by two‐dimensional sodium dodecyl sulfate‐polyacrylamide gel electrophoresis revealed only CD3‐associated 35 kDa/45 kDa γ/δ heterodimers. The demonstration of TcR heterodimers on resident Thy‐1DEC strongly implies that these cells are functional T cells. The selective expression of C_γ1/δ (C57BL/6) and C_γ1/δ or C_γ2/δ (C3HkIe) TcR makes these cells useful for the study of γ/δ TcR function.