Streptozotocin-diabetic BB/OK rats accept permanently BB/OK-islet grafts without immunosuppression.

The recurrence of hyperglycaemia after transplantation of BB rat islets in partially inbred BB rats with an autoimmune diabetes could be either caused by graft rejection or by autoimmune destruction. We investigated in the BB/OK rat substrain which does accept BB/OK rat skin grafts permanently, the survival of BB/OK islet grafts by using streptozotocin-diabetic BB/OK rats as recipients. We observed a permanent acceptance of islet grafts despite using animals inbred for only 8 generations. The results demonstrated homogeneity for islet grafts and provide evidence that an autoimmune B-cell destruction cannot be triggered by a direct (toxic effect on immune cells) or indirect (due to B-cell killing) action of a single large doses of streptozotocin in BB/OK rats.