Expression of E-cadherin by murine dendritic cells: E-cadherin as a dendritic cell differentiation antigen characteristic of epidermal Langerhans cells and related cells*
Murine epidermal Langerhans cells (LC) synthesize and express E-cadherin, a homophilic adhesion molecule that mediates adhesion of LC to keratinocytes in vitro. To determine if E-cadherin expression is characteristic of LC or is a feature of all dendritic cells (DC), we studied DC from various lymphoid tissues and peripheral blood for reactivity with anti-E-cadherin monoclonal antibody. By flow cytometry, DC prepared from skin-associated lymph nodes (LN) expressed E-cadherin, whereas DC prepared from gut-associated LN and spleen did not. However, direct comparison revealed that levels of E-cadherin expressed by DC from skin-associated LN werefivefold lower than those expressed by freshly-prepared LC. Immunohistochemical studies confirmed that E-cadherin was expressed by DC in skin-associated LN in situ, and demonstrated that the number of E-cadherin+ DC in LN draining skin previously treated with the contact allergen 2,4,6-trinitrochlorobenzene was increased relative to the number of E-cadherin+ DC present in LN draining normal skin. DC propagated from the blood of cyclophosphamide-treated mice in granulocyte/macrophage-colony stimulating factor-supplemented media also expressed E-cadherin. E-cadherin immunoprecipitated from DC co-migrated in SDS polyacrylamide gels with that from fibroblasts transfected with murine E-cadherin cDNA, and mRNA encoding extracellular and intracellular regions of E-cadherin was present in DC propagated from blood. These results indicate that E-cadherin expressed by murine dendritic cells is identical to E-cadherin expressed by epithelial cells, and suggest that E-cadherin represents a DC differentiation antigen characteristic of LC and lineage-related cells (skin-associated LN DC).