Inflammatory bowel diseases and thymus disorder: reactivity of thymocytes with monoclonal antibodies.

Thymectomy is one of the most effective means of treating myasthenia gravis (MG). Formation of lymphoid follicles in the thymus is seen at high rate in ulcerative colitis (UC) as well as MG. We examined the subsets of lymphocytes in the thymuses taken from patients with inflammatory bowel diseases (IBD), using OK series monoclonal antibodies. Decreases in OKT8 (CD8)-, 6(CD1)- and 10-positive cells and an increase of IA1-positive cells were observed in UC. In contrast, there were no significant changes in Crohn's disease (CD). Therefore, the thymocytes from UC appear to consist of comparatively matured cells under the influence of thymic hormone.