We investigated the ability of isolated human colonic epithelial cells to express the common acute lymphoblastic leukemia antigen (CALLA), the transferrin receptor, and the 4F2 antigen in response to different types of stimuli. The expression of these markers was assessed by immunofluorescence using monoclonal antibodies. Thirty-two percent of freshly isolated colonic epithelial cells from actively inflamed mucosa of patients with inflammatory bowel disease expressed the 4F2 antigen, 28% the transferrin receptor, and 13% the CALLA. Normal colonic epithelial cells were cultured and the kinetics of expression of the three antigens was studied. A significant increase in the expression of the three markers was observed throughout the culture period in response to the lectin phytohemagglutinin and the epidermal growth factor. The kinetics of expression of the 4F2 antigen and the CALLA after lectin stimulation appeared to differ from that observed after epidermal growth factor. At the end of the cultures one-third of the cells expressed the 4F2 antigen and the transferrin receptor, whereas one-fifth were positive for CALLA. Thus, after these cultures the expression of the three markers was quantitatively similar to that observed with freshly isolated cells from inflamed mucosa. γ-Interferon markedly induced the 4F2 antigen but had no effect on the transferrin receptor and the CALLA. These data demonstrate that colonic epithelium is capable of expressing the 4F2 antigen and the CALLA in association with the transferrin receptor.