Islet transplantation in experimental diabetes of the rat. X. Induction of cytotoxic antibodies and islet-cell-surface-antibodies after homologous islet transplantation in rats.

The mechanisms of islet allograft rejection are still unknown. 350 allogeneic rat islets (BDE/Han) were transplanted into the liver of Streptozotocin-diabetic rats (Lewis/Han). Animals were killed either on day 4, 7, 10 or 14. Immunofluorescence analysis for islet-cell-surface-antibodies (ICSA) was performed on BDE-islet-single-cells yielded by Collagenase-Dispase digestion. In order to detect cytoplasmic islet cell antibodies, immunofluorescence technique was used on BDE-pancreas cryosections. Cytotoxicity assay was tried out using 51Cr-release-test. After successful intraportal transplantation, rejection took place between day 7 and 10. ICSA could be observed on day 10 and 14. Cytoplasmic antibodies were not detected at any time. A specific cytotoxic activity in the recipient serum revealed itself on day 10 (23.0%) and day 14 (27.7%). Transplantation of freshly isolated allogeneic islets induced ICSA and cytotoxic antibodies. These results indicate an involvement of humoral mechanisms in islet allograft rejection.