Abnormalities of the local immune system in intestinal neoplasia: a morphological study.

In colonic adenocarcinomata abnormalities have been noted in all morphological aspects of the local immune system of the bowel; thus, in such tumours there is a defective production of secretory IgA, a diminished content of secretory component (SC) and a marked decrease in intraepithelial lymphocytes. By contrast, no such abnormalities were noted in the non-neoplastic areas of the bowel, either immediately adjacent to, or some distance from, the carcinoma. These findings suggest that there is not usually any generalised morphological abnormality of the local immune systems in intestinal neoplasia and that the immunological abnormalities noted within the tumour are a result of the changed nature of the epithelium, thus altering, or interfering with, the normal interactions between epithelial and lymphoid tissue in the gut.