Immunohistologic Study of Ulcerative Colitis With Monoclonal Antibodies Against Tumor-Associated and/or Differentiation Antigens

We used monoclonal antibodies (MAbs) (19-9, 55-2, and 73-3) that detect tumor-associated or differentiation antigens, or both, to immunohistochemically study a well-defined group of patients with ulcerative colitis. Monoclonal antibody 19-9 detects the gastrointestinal cancer-associated antigen (sialylated Lewis A). Monoclonal antibody 55-2 detects the Lewis Y antigen and reacts with deep crypt cells in the normal colon. In the normal colon MAb 73-3 reacts with mature superficial columnar cells detecting the protein moiety of a 35,000-dalton glycoprotein. In cases of inactive or mildly active disease, MAbs 19-9, 55-2, and 73-3 had staining patterns similar to normal colon. In 72% and 44% of cases of severely active disease, MAb 19-9 and MAb 73-3, respectively, reacted with epithelial cells at all levels of the crypt, whereas MAb 55-2 reacted only with deep crypt cells. Monoclonal antibodies 19-9, 55-2, and 73-3 reacted with dysplastic epithelium in 70%, 10%, and 60% of cases, respectively. In severely active disease, proliferating epithelial cells “paradoxically“ express markers of differentiated epithelium throughout the entire crypt. Similarly, colonic epithelial cells may have the ability to reversibly express tumor-associated antigens. Unfortunately, the MAbs used in this study cannot differentiate dysplasia from reactive epithelium.