EXPRESSION OF ADHESION MOLECULES ICAM-1 AND LFA-3 IN COLORECTAL ADENOMAS AND CARCINOMAS

Tumor cells can escape immune recognition in vivo by at least three possible means: altered expression of HLA molecules, immunogenic peptides or accessory molecules involved in cell adhesion. The immunohistochemical expression of the adhesion molecules LFA-3 and ICAM-1 was examined in 15 colorectal adenomas and 56 carcinomas. None of the adenomas and only 1 of the carcinomas showed loss of LFA-3, while ICAM-1, which is not normally expressed in colonic epithelium, was detected de novo in 3 cases. These findings question the hypothesis that neoplastic alterations of LFA-3 and/or ICAM-1 expressed by tumor cells play a major role in the evasion of immune recognition by cytotoxic T lymphocytes.