Expression of Forssman antigen in human large intestine.

Forssman antigen is a commonly occurring heterophile antigen but is thought not to be present in most humans. Recent biochemical studies, however, have shown the presence of Forssman antigen in several forms of human cancer, including gastric, colon, and lung cancers. Immunohistochemical staining with both monoclonal and polyclonal antibodies has failed to demonstrate this antigen in human tissues. In this study we conclusively demonstrated the presence of Forssman antigen in cytoplasm of colon goblet cells, especially those in the so-called transitional mucosa adjacent to carcinoma. Specimens from 69 of 70 patients with colon cancer contained the antigen in goblet cells in transitional mucosae. The antigen was successfully demonstrated only after removal of sialic acid by alkaline hydrolysis-neuraminidase digestion. Localization of the antigen was quite different from that of Tn and human blood group A, B, and H antigens. This antigen was thought to be associated exclusively with globo-series glycolipids, and its existence in glycoproteins has not been conclusively demonstrated. However, the results presented here, based on proteolytic digestion and lipid extraction studies, strongly suggest that the antigen is also contained in glycoproteins.