Impaired lymphocyte reactivity against tumour cells in patients with Crohn's disease.

Evidence is presented which indicates a possible reduction in recognition capacity for tumour cell antigens (EB(2) Burkitt lymphoma cell line) by lymphocytes from some patients with longstanding but inactive Crohn's disease. Three out of seven patients tested also showed diminished or absent lymphocytotoxicity when their cells were grown in mixed culture with chromium-labelled lymphoma cells and absent response has never been observed in a large series of controls similarly tested. In both test systems impaired reactivity appeared to be partly caused by a factor present in Crohn's disease serum. Increased tumour incidence in Crohn's disease may in part be attributable to defective immune surveillance and the histology of Crohn's disease could reflect an imbalance between the proliferative and the cytotoxic responses of lymphocytes to various antigens in the bowel lumen in this disease.