Morphology of rejection in experimental pancreas transplantation and its modification by cyclosporin A administration.

Histology of pancreas transplant rejection is complicated by non-specific appearances related to undrained exocrine secretions. Using a rat model of pancreas transplantation with exocrine drainage into the urinary tract, morphology of acute rejection has been studied with minimal interference from non-specific change. Unmodified acute rejection was complete after 7-9 days. Intralobular lymphocytic infiltration, which differentiated allografts from isografts, was present 5 days after transplantation and lymphocytic infiltration of islets and blood vessel walls developed between 5th and 7th days. Cyclosporin A immunosuppression of allografts resulted in marked attenuation of the cellular infiltrate. The nature of the infiltrate and its suppression with cyclosporin A indicated an allograft reaction.