Leucocytotoxicity in malignant and non-malignant colonic diseases.

The survival of cells from five different cultures of allogeneic malignant colonic carcinoma, two from normal adult colonic epithelium and eight from foetal colonic epithelium in the presence of leucocytes from patients with neoplastic and inflammatory disorders of the colon has been compared. Cytotoxicity assessed by the reduction of the number of adherent target cells in microplate wells compared with those surviving in wells treated with tissue culture medium alone was observed with leucocytes from donors in all categories examined including those from individuals without any known abnormality. Patients with ulcerative colitis were the only group to reveal consistent reactivity against cultures derived from all three sources, an observation which may reflect sensitization to organ-related antigens in this disease. In contrast, leucocytes from patients with bowel neoplasia showed reactivity for cells derived from colon carcinoma tissue, which was comparable to that of healthy donors. Evidence for tumour-specific cytotoxicity was therefore lacking in this study. It is suggested that the detection of tumour-associated antigens on cultured cells may be limited by a number of factors of which the wide variation in reactivity among controls and unspecified nature of the target cells are likely to be of greatest importance.