Murine dendritic epidermal T cells (DETC) express the homophilic adhesion molecule E-cadherin

Cadherins mediate homotypic intercellular adhesion in epidermis and other epithelia. E-cadherin is also involved in interactions between murine epidermal Langerhans cells (LC) and keratinocytes (KC). Dendritic epidermal T cells (DETC) comprise another subpopulation of epidermal leukocytes. Using flow cytometry, we determined that DETC expressed levels of E-cadherin similar to those expressed by LC and KC. DETC also adhered congruent to three-fold better to KC and E-cadherin-transfected fibroblasts than to normal fibroblasts. Treatment of DETC with trypsin in the absence of calcium caused a loss of E-cadherin and resulted in an congruent to 80% decrease in DETC-KC adhesion whereas treatment of DETC with trypsin in the presence of calcium did not significantly affect E-cadherin expression or DETC-KC binding. Thus, E-cadherin may be involved in adhesion of DETC to KC. DETC are derived from TCR V gamma 3+ thymocytes that transiently populate embryonic murine thymus. We determined that TCR V gamma 3+ thymocytes as well as other early (fetal day 16) TCR gamma/delta+ thymocytes expressed E-cadherin; TCR gamma/delta+ (TCR V gamma 3-) thymocytes that developed later did not. These results indicate that cells of the T cell lineage can express E-cadherin, and suggest that E-cadherin may play a role in adhesion of DETC (and/or DETC precursors) to KC.