Peripheral blood mononuclear-cell interleukin-2 production, receptor generation and lymphokine-activated cytotoxicity in inflammatory bowel disease

The interleukin-2 pathway is essential for the normal immune response to antigen stimulation; we have examined the possibility that this may underlie abnormal peripheral blood lymphocyte immunoregulatory function that has been observed in patients with inflammatory bowel disease. We studied 11 patients with Crohn's disease and 5 with ulcerative colitis, all with quiescent disease activity. Peripheral blood mononuclear cells were isolated from these patients and from healthy age- and sex-matched controls. Interleukin-2 production after mitogen and phorbol-myristate acetate stimulation was similar in both groups: 381±71 (mean ± SE) U/ml by control cells and 451±70 by patient cells. Interleukin-2 receptor generation was also measured pre- and poststimulation by labeling with anti-Tac antibody. This was 10.45±1 and 69.95±3.85% for control cells and 11.41±1.38 and 60.9±4.25% for patients cells. Finally, we examined the response of these cells to interleukin-2 stimulation by generating cells with direct cytotoxicity to⁵¹Cr-labeled Daudi-cell targets. Control cells caused 59.5±46%⁵¹Cr release, whereas patient cells caused 50.8±5.18% release. None of the above results achieved statistical significance. We conclude that the peripheral blood interleukin-2 pathway is normal in inactive inflammatory bowel disease.