Immunohistochemical changes in morphologically involved and uninvolved colonic mucosa of patients with idiopathic proctitis.

Alterations in secretory component, IgA, IgG, and IgM were studied by immunofluorescent techniques in mucosal biopsy specimens obtained at colonoscopy from inflamed and grossly uninvolved colonic mucosa from 12 patients with idiopathic proctitis. Parotid-salivary secretory component and IgA and serum immunoglobulins were also investigated. Decreased secretory IgA was observed in the epithelium of all grossly involved rectal mucosa and in 40% of proximal normal mucosa. Salivary secretory IgA was not diminished. These observations suggest that a local immune defect may be pathogenetically related to idiopathic proctitis.