Serum lymphocytotoxins in inflammatory bowel disease. Studies of frequency and specificity for lymphocyte subpopulations.

Serum cold-reactive lymphocytotoxin (LCT) was detected in twenty-two of fifty-six (40%) patients with inflammatory bowel disease (IBD). The frequency of LCT detection was similar in Crohn's disease and ulcerative colitis. Cytotoxicity testing against T or B cell-enriched peripheral blood lymphocytes from normal donors, together with absorption experiments, indicated that LCT in IBD was reactive against determinants on both cell subpopulations. Reactivity against T cells from patients with common variable immunodeficiency was significantly less than with normal donor T cells. LCT in IBD could not be related to prior allogeneic sensitization and its presence appeared to be unrelated to disease activity or drug therapy. No correlation was found between LCT and peripheral blood T- or B-cell numbers. The present findings suggest the need for further investigation of the role of infectious agents in the pathogenesis of IBD.