[Morphological, histochemical and immunochemical characteristics of the terminal ileum of patients with ulcerative colitis. Relationship with the development of pouchitis].

Unlabelled: Pouchitis is the most frequent long-term complication of the ileoanal reservoirs. Its etiology is unknown and it is currently believed to be a recurrence of ulcerative colitis in the mucosa of the ileal reservoir.

Aim: To evaluate whether the mucosa of the terminal ileum of patients with ulcerative colitis is different from that of patients free of this disease and whether there are morphological and immunological alterations which might predispose to inflammation of the reservoir.

Patients And Methods: Colectomy samples from the terminal ileum of 20 patients (12 women, 8 men) with ulcerative colitis who had undergone restorative proctocolectomy with ileoanal reservoir and of 10 controls who had undergone right hemicolectomy for other causes were studied. During follow-up (46.9 months) seven patients were diagnosed with pouchitis (Sandborn > 7). In all patients, morphometric histopathologic, histochemical and immunohistochemical studies of the ileal mucosa were performed.

Results: Chronic inflammatory infiltrate and the degree of villous atrophy and of global chronic inflammation were significantly higher in the terminal ileum of patients with ulcerative colitis than in the control group. There were no differences in the mucin content between the two groups and IgA, IgG and B lymphocyte expression was significantly higher in the terminal ileum of patients with ulcerative colitis. Chronic inflammatory infiltrate, degree of atrophy, villous atrophy and of global chronic infiltration, macrophage and CD8 lymphocyte expression were higher in the terminal ileum of patients with pouchitis, but differences was not significant.

Conclusions: The terminal ileum of patients with ulcerative colitis has histopathologic, morphometric and immunohistochemical characteristics that are different from those of patients without this disease. These results may eventually lead to an association between alterations in the ileum and the subsequent development of pouchitis.