EXPRESSION OF GP40, THE MURINE HOMOLOG OF HUMAN EPITHELIAL-CELL ADHESION MOLECULE (EP-CAM), BY MURINE DENDRITIC CELLS

Dendritic cells (DC) can be distinguished from other antigen-presentin g cells (APC) by their morphology, motility and ability to initiate pr imary responses in naive T cells. Certain cell surface proteins (e.g. major histocompatibility complex antigens, co-stimulatory/adhesion mol ecules and DEC205) are selectively expressed by DC, and may contribute to the potent APC activity of these leukocytes. As an outgrowth of st udies of adhesion molecules expressed by epithelia and Langerhans cell s (LC), we examined DC from murine epidermis and various lymphoid tiss ues for evidence of expression of gp40, a glycoprotein recently identi fied as the murine homologue of human epithelial cell adhesion molecul e (Ep-CAM). gp40 was detected on freshly-obtained LC, cultured LC and LC that migrated from skin explants, as well as on keratinocytes. In s kin-associated lymph nodes, gp40 was selectively expressed by some DC in T cell-dependent areas. DC-enriched preparations from skin-associat ed lymph nodes and spleen contained many cells that co-expressed DC ma rkers (CD11c and DEC205) and high levels of gp40. Lower levels of gp40 were present on DC from gut-associated lymph nodes. These results dem onstrate that the putative hemophilic adhesion molecule gp40 is expres sed by subpopulations of DC in selected tissues: we propose that gp40 expression may have functional consequences for DC.