Lymphocyte subpopulations, lymphoblast transformation activity, and concanavalin A-induced suppressor activity in patients with ulcerative colitis and Crohn's disease.

The following immunologic in vitro tests were applied on peripheral blood mononuclear cells (PBMC) from patients with chronic inflammatory bowel disease (IBD): concanavalin A (Con A)-induced suppressor test, Con A-activated lymphoblast transformation test, and spontaneous lymphoblast transformation test. Concomitant phenotypic characterization of subsets of PBMC was performed with monoclonal antibodies. Patients with ulcerative colitis and a control group with rheumatoid arthritis showed significantly reduced activity in the Con A-activated lymphoblast transformation test compared with healthy controls and patients with Crohn's disease. The distribution of PBMC subsets and the results of the other in vitro tests were similar for patients with IBD and healthy controls. Thus the decrease in Con A-activated lymphoblast activity was not due to an increased suppressor function as measured either by functional Con A-induced suppressor test or indirectly by T8 phenotype.