Immunohistochemical localization of Y hapten and the structurally related H type-2 blood-group antigen on large-bowel tumours and normal adult tissues.

The monoclonal antibody C14/1/46/10 which defines the Y hapten carbohydrate antigen (Brown et al., 1983) was shown, by the indirect immunoperoxidase technique, to stain tissue sections of 96% of colo-rectal adenocarcinomas and 100% of colo-rectal adenomas. In contrast, a monoclonal antibody defining the related H type-2 blood-group antigen was found to stain 86% of adenocarcinomas and 32% of adenomas. In adenocarcinomas the percentage of cells stained for both antigens was, on average, greater in group O than in group A patients. In adenomas a focal pattern of expression was observed, for both Y hapten and H type-2 antigen, that was characteristic of group A but not group O adenocarcinomas. In the normal mucosa of the distal colon, whilst H type-2 antigen was absent, Y hapten was found in the immature cells of the crypt bases. A comparison of the cellular phenotypes present in adenocarcinomas, adenomas and normal mucosa of the distal colon supports the adenoma-carcinoma sequence hypothesis for the genesis of colo-rectal carcinomas. In normal adult tissues Y hapten was predominantly found on epithelial cells whilst nervous tissues, muscles and connective tissues were negative. The expression of Y hapten in several positive tissues was dependent upon secretor status. A comparison of the expression of Y hapten and H type 2 antigen on normal adult tissues revealed that all of the permutations of expression of these two structurally related antigens were possible.