Immunohistochemical staining of colorectal tissues with monoclonal antibodies to ras oncogene p21 product and carbohydrate determinant antigen 19-9.

Two monoclonal antibodies were applied to benign, dysplastic, and malignant human colorectal tissues using immunohistochemical techniques on formalin fixed paraffin embedded material. RAP-5 antibody is directed against a synthetic peptide, reflecting an amino acid sequence of the ras oncogene p21 protein product. Despite using several different techniques and antibody dilutions differential staining between the various epithelial populations was not obtained. RAP-5 also showed other tissue components such as plasma cells, histiocytes, fibroblasts, smooth muscle and vascular endothelium. CA19-9 antibody recognizes an epithelial surface carbohydrate antigen originally derived from a human colorectal carcinoma cell line: it did not stain normal colorectal mucosa or adenomatous polyps, but showed focal expression of variable strength in regenerative, dysplastic, and cancerous mucosa in ulcerative colitis, and in non-colitic colorectal carcinoma. Neither antibody was found to be a reliable marker of the evolution of malignant mucosal changes, although CA19-9 may be of limited use in confirming adenocarcinoma of gastrointestinal origin.

An immunoperoxidase study of epithelial marker antigens in ulcerative colitis with dysplasia and carcinoma.

An immunoperoxidase technique was applied to formalin and Helly fixed paraffin wax sections from cases of ulcerative colitis complicated by dysplasia and carcinoma for carcinoembryonic antigen and components of the colonic secretory immunoglobulin system--namely, secretory component, IgA, and J chain. Sections from both resection specimens and mucosal biopsies were available. Intensity of immunostaining was assessed qualitatively. There was appreciable variation in expression of carcinoembryonic antigen and secretory component antigens. Carcinoembryonic antigen stained heavily in dysplasia and carcinoma while these tissues showed only focal light staining for secretory component. Normal tissue stained heavily for secretory component. The variation in staining intensity for both carcinoembryonic antigen and secretory component in inflamed and regenerative mucosa precluded their use as a reliable diagnostic aid in discriminating these tissues from true dysplasia. Loss of secretory component production or transport or both may be incurred during malignant change, but it should not be assessed as an isolated index of epithelial maturity. The relation with mucosal plasma cells warrants further study to determine more fully the factors affecting tissue secretory component expression.