Tumor-associated glycoprotein (TAG-72) expression in ulcerative colitis.

Abstract

Monoclonal antibody (MAb) B72.3 reactive with the high-molecular-weight (Mr greater than 10(6) tumor-associated glycoprotein (TAG)-72 is being increasingly utilized in vivo and in vitro for a variety of purposes in colon cancer patients. Recent evidence has suggested that the TAG-72 antigen expression may be enhanced in inflammatory bowel disease, particularly ulcerative colitis (Thor et al., 1986a: Cancer Res., 46, 3118-3124). We have utilized 117 paraffin-embedded formalin-fixed colonic specimens from 56 ulcerative colitis patients which demonstrate a spectrum of epithelial abnormalities (reactive atypia, dysplasia, and carcinoma) as well as 11 inflammatory controls to evaluate TAG-72 expression. Our selected patient population all had pan-colitis and demonstrated a generally increasing incidence of dysplasia or carcinoma with duration of disease (20% at 0 to 10 years, 50% at 11 to 20 years, 59% at 21 to 30 years, and 100% at more than 31 years). TAG-72 expression was similar in the control and non-dysplastic colonic epithelia, and increased with low- or high-grade dysplasia as well as carcinomatous lesions (mean cellular reactivities 23.7%, 26.5%, 36.7%, 70% and 84.3%, respectively). Epithelium with low-grade dysplasia exhibited a focal perinuclear, superficial crypt staining (when present). High-grade dysplastic epithelium showed pancytoplasmic, pan-cryptic reactivity. Invasive disease showed cytoplasmic as well as extracellular mucin staining. Biopsies from patients with active disease showed significantly more immunoreactive cells for TAG-72 than patients with quiescent disease. For any given biopsy specimen the percentage of cells reactive did not always correlate with the degree of dysplasia. TAG-72 expression in quiescent disease generally increased with duration of disease, in contrast to active disease which showed no correlation between MAb B72.3 staining and duration of disease. The frequent expression of TAG-72 in actively inflamed colonic mucosa (ulcerative colitis and other colitides) may limit the clinical utility of this antigen for detecting colon cancer in ulcerative colitis patients by serological assay or in vivo radiolocalization techniques. The tendency for TAG-72 expression to correlate with disease duration in patients with quiescent disease and to increase with more severe degrees of dysplasia suggests that the expression of this gene product correlates with the dysplasia-to-carcinoma sequence.