Immunoreactive alpha-interferon in insulin-secreting beta cells in type 1 diabetes mellitus.

Of 37 pancreases removed at necropsy from patients with type 1 diabetes 34 had residual beta cells. In 33 of the 34 the beta cells were positive for immunoreactive alpha-interferon, and this finding in islets was related to hyperexpression of class I major histocompatibility complex (MHC) antigens. Of islets showing class I hyperexpression 93% contained alpha-interferon compared with 0.4% of those showing no hyperexpression. Among 80 control pancreases significant numbers of beta cells containing alpha-interferon were present only in 4 cases of acute infantile viral pancreatitis, known to be caused by Coxsackie-B viral infection in 3 cases. Chronic viral infection of beta cells may underlie the pathogenesis of some cases of type 1 diabetes.