Impaired Lymphocyte Responsiveness in Inflammatory Bowel Disease

The in vitro responsiveness of circulating lymphocytes to the nonspecific mitogen, phytohemagglutinin, was studied in 58 patients with Crohn's disease, 18 patients with ulcerative colitis, and 21 normal control subjects. Lymphocyte responsiveness was impaired in about one-third of all the patients with inflammatory bowel disease, Crohn's disease and ulcerative colitis alike. This phenomenon of depressed lymphocyte responsiveness did not correlate with anatomical extent, duration, or activity of disease, nor with the presence or absence of lymphopenia. The phenomenon was not attributable to a plasma factor nor to treatment with salicylazosulfapyridine. We have concluded that impaired lymphocyte responsiveness reflects an intrinsic defect of the immunocyte system which occurs equally in patients with Crohn's disease and ulcerative colitis.