Gastrointestinal carcinoma-associated antigen detected by a monoclonal antibody in dysplasia and adenocarcinoma associated with chronic ulcerative colitis.

Colorectal tissue specimens from 13 patients with chronic ulcerative colitis, of whom all had epithelial dysplasia and 2 had adenocarcinoma, were tested for the presence of gastrointestinal carcinoma-associated antigen (GICA), using an immunoperoxidase technique with a monoclonal antibody (MAb) against this antigen. GICA was present in the formaldehyde-fixed and paraffin-embedded sections of dysplastic and cancer tissue but absent from normal or hyperplastic epithelium. However, the pattern and extent of staining with the antibody did not correlate with the degree of dysplasia, i.e., "mild" dysplasia was often positive, and "severe" dysplasia was sometimes negative. Changes classified as "indefinite for dysplasia but probably negative" were variable in their expression of GICA. The adenocarcinomas were selectively labelled within cell clusters. In contrast, ulcerative colitis (UC) patients with severe inflammatory changes but with no detectable dysplasia were negative for GICA. GICA could be eluted from paraffin blocks of dysplastic tissue and biochemically characterized as a glycolipid. The detection of this antigen might be a useful complement to morphological examination in discriminating between precancerous and benign epithelial lesions of the colon.