Expression of a Tn-like epitope by carcinoma cells

A monoclonal antibody, FBT3, was raised against Tn positive erythrocytes and, using immunohistochemistry, fresh and fixed tissues from patients with cancer were studied to detect any expression of a Tn-like epitope. Expression was found in neoplastic cells, usually both in cytoplasm and on cell membranes, from 104 of 147 cases of carcinoma and 1 of 13 cases of lymphoma, but rarely in adjacent, morphologically normal cells. Tn expression was seen in some normal glandular cells but, unlike cancer cells, it was distributed as fine granules in a supranuclear position. Detection of a Tn-like epitope is of theoretical interest and may be of direct diagnostic value.