"Insulin" induced insulitis.

Insulitis, an inflammatory process restricted to the pancreatic islets, can experimentally be induced by active immunization with insulin or passive transfer of anti insulin serum. --Mice and rats injected with anti insulin serum from guinea pigs develop a polymorphcellular islet infiltration composed of many eosinophiles and neutrophiles. This inflammatory reaction is caused by the occurrence of immune complexes within the islet area produced by the injected insulin antibodies and the endogenous insulin. Thus polymorphcellular immune complex insulitis represents a type III immune response, respectively a local Arthus phenomenen. --Cattle, sheep and rabbits immunized with crystalline insulin preparations and Freund's adjuvant were found to develop a lymphoidcellular insulitis. As far as specific localization, histologic features, ultrastructure and an occasional manifestation of a diabetes mellitus-like syndrome are concerned lymphoidcellular immune insulitis suggests an immune response of the cell mediated type with temporary autoimmune characteristics to endogenous insulin evoked by the immunization with exogenous crystalline insulin. Insulin derivatives are the most probable candidates for the assumed insulitis-inducing antigen. --Whether immune reactions may also play a role in the pathomechanisms leading to human insulitis is until now an unsolved question.