Expression of 7F7-antigen, a human adhesion molecule identical to intercellular adhesion molecule-1 (ICAM-1) in human carcinomas and their stromal fibroblasts.

The 7F7-antigen is a widespread 85-kDa membrane adherence molecule involved in heterotypic adhesion between PHA-blasts and fibroblasts. Immunofluorescence analysis of COS cells transfected with clone pICAM-I indicated that 7F7-antigen is identical with ICAM-I, the ligand for the contact molecule LFA-I. We have investigated the expression of ICAM-I on several human carcinomas. Tumor cells in most carcinomas, with the exception of squamous-cell carcinomas, expressed very little ICAM-I or none at all. In contrast, marked expression of this molecule was observed on fibrous tissue in the vicinity of carcinoma cells, its intensity correlating with lymphatic infiltration in these tumors. We also examined the expression of ICAM-I on carcinoma cell lines and its induction by treatment with interferon-gamma (IFN-gamma). The inducibility of ICAM-I expression on cultured fibroblasts by several lymphokines suggests that the expression of ICAM-I in the vicinity of carcinoma cells is effected by lymphokines produced by activated lymphocytes/macrophages within the tumor.