Different expression of E-cadherin by two cutaneous γ/δ TcR⁺ T-cell subsets, Vγ5^- and Vγ5⁺ γ/δ TcR⁺ T cells

Recently we have demonstrated that, besides Vγ5⁺ γ/δ TcR⁺ T cells (Vγ5⁺ γ/δ T cells), Vγ5^- γ/δ TcR⁺ T cells (Vγ5^- γ/δ T cells) are also present in murine skin. In the present study, to characterize the functional differences between these two different cutaneous γ/δ T cells we examined the expression pattern of E-cadherin and its two integrins. After co-culturing of Ly-5⁺ epidermal cells and migrating cells from organ-cultured murine skin with cutaneous stromal cells, we could expand Vγ5⁺ γ/δ T cells and Vγ5^- γ/δ T cells, respectively. Flow cytometry demonstrated that cultured Vγ5⁺ γ/δ T cells expressed E-cadherin, but Vγ5^- γ/δ T cells did not. This difference in E-cadherin expression was also observed in freshly isolated Vγ5⁺ and Vγ5^- γ/δ T cells. On the other hand, both Vγ5⁺ and Vγ5^- γ/δ T cells expressed the α chain of the vitronectin receptor, but did not express the α4 integrin. Of these two cutaneous γ/δ T cells, only Vγ5⁺ γ/δ T cells adhered to murine keratinocyte cell line, PAM 212 cells. Unexpectedly, however, the adhesion of E-cadherin-expressing Vγ5⁺ γ/δ T cells to PAM 212 cells was not inhibited by anti-E-cadherin antibody, which effectively abrogated the adhesion of Langerhans cells to PAM 212 cells. These distinct phenotypic and functional characteristics in the subsets of cutaneous γ/δ T cells may suggest that they reside in different locations in the skin to play different functional roles in skin immunophysiology.