Dendritic interdigitating cells isolated from lymph nodes, Langerhans' cells from skin and dendritic cells from the spleen have been tested for expression of the mucosal T cell integrin alpha M290 beta 7. Almost all interdigitating cells isolated from mesenteric lymph nodes expressed the integrin at high levels; 50-60% of those from lymph nodes draining non-mucosal sites also expressed this adhesion molecule. In contrast, alpha M290 beta 7 was not detected on either Langerhans' cells or splenic dendritic cells. Because this integrin has recently been shown to recognize a ligand that seems to be expressed mainly or exclusively by epithelial cells; it is proposed that this adhesion pathway may be important for antigen sampling by dendritic cells in mucosal tissues.