Autoimmunity, inflammatory bowel disease and hyposplenism.

The presence or absence of nine autoantibodies were assessed in 44 patients with ulcerative colitis (17 with hyposplenism) and 22 patients with Crohn's disease (eight with hyposplenism). The purpose of the study was to determine whether hyposplenism in inflammatory bowel disease is associated with an increased tendency to autoimmunity, or whether autoimmunity is linked not to hyposplenism itself but to the underlying bowel disease. The results strongly suggest that the latter hypothesis is correct. There was a much higher frequency of autoantibodies in patients with ulcerative colitis than in those with Crohn's disease (P < or = 0.01), suggesting that autoimmune factors are more important in the pathogenesis of ulcerative colitis than in Crohn's disease.