Differentiation-related expression of the Thomsen-Friedenreich glycotope in developing human lung and in lung carcinoma - Lack of association with malignancy

BACKGROUND. It has been proposed that the Thomsen-Friedenreich glycotope re presents a general carcinoma-associated antigen and a candidate for the dev elopment of a tumor vaccine. However, the expression of the unmasked and ma sked (sialylated) forms in lung carcinomas, as well as in developing and ad ult human lung, has not been documented sufficiently. METHODS. Sections from 82 lung carcinomas, including squamous cell carcinom as, adenocarcinomas, and large cell and small cell carcinomas, as well as s ections of developing and adult human lung were studied using the lectin am aranthin and a monoclonal antibody. RESULTS. All lung carcinomas but one bronchiolo-alveolar carcinoma were unr eactive for the Thomsen-Friedenreich glycotope, whereas its sialylated form was detectable in well-differentiated squamous cell carcinomas and adenoca rcinomas, including bronchiolo-alveolar carcinomas. Both unmasked and maske d Thomsen-Friedenreich glycotopes were undetectable in large cell and small cell lung carcinomas. In all developmental stages of lung, the Thomsen-Fri edenreich glycotope was expressed only in epithelia of the most peripheral parts of the bronchial tree, whereas its sialylated form was expressed in e pithelia of all parts of the bronchial tree. In adult lung, the Thomsen-Fri edenreich glycotope was expressed in pneumocytes, whereas its sialylated fo rm was expressed ubiquitously in all epithelia. CONCLUSIONS. The Thomsen-Friedenreich glycotope in human lung represents a differentiation antigen, rather than a carcinoma-associated antigen. The si alylated form is expressed constitutively in both developing and adult lung and well-differentiated lung carcinomas. Thus, the Thomsen-Friedenreich gl ycotope is of limited value in the diagnosis of lung carcinoma, and there i s no rationale for a Thomsen-Friedenreich glycotope-based immunotherapy for patients with this disease. Cancer 1999;85:2151-9. (C) 1999 American Cance r Society.