An immunohistochemical study of a colonic mucus antigen in normal and neoplastic gastrointestinal tissues.

A monoclonal antibody YPC 44.3 which reacts with human large intestinal goblet cell mucus has been used to examine normal gastrointestinal mucosa and a series of gastric and colorectal carcinomas in an immunohistochemical study. In normal colonic mucosa the antibody is shown to detect an antigen which is expressed polymorphically and depends on the presence of the active allele at the Lewis locus for its expression. However the antigen appears distinct from regular Lewis antigens on the basis of immunoabsorption studies and organ distribution. Results of immunostaining tumours show no correlation with the site, classification or grade of tumour or the type of metaplasia adjacent to gastric cancers. The relationship of YPC 44.3 to other mucus antibodies and the importance of screening tissues with a wide range of blood group phenotypes is discussed.