Expression of gp40, the murine homologue of human epithelial cell adhesion molecule (Ep-CAM), by murine dendritic cells

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