Cytotoxic effects of islet cell surface antibodies

Antibodies against rat islet cells were produced by immunisation of rabbits with neonatal rat islet cells. In the presence of complement the rabbit anti-rat islet cell surface sera were strongly cytotoxic for both, neonatal rat islet cells and spleen lymphocytes as revealed by the high percentage of 51Cr release from these cells. However, after absorption with rat lymphocytes and rat liver powder the cytotoxicity of the islet cell antisera for rat lymphocytes was drastically reduced while the release of 51Cr from islet cells was only slightly influenced. These data indicate that islet cell specific antibodies were still present in the antisera after absorption. Native normal rabbit serum was also cytotoxic for neonatal rat islet cells and spleen lymphocytes. The release of 51Cr from islet cells and lymphocytes was vigorously reduced after absorption of the normal rabbit serum with lymphocytes and was paralleled by a similar decrease of insulin release from intact islets under conditions where the active insulin secretion was blocked pharmacologically. Intact islets prelabeled with 51Cr were also used as targets but this approach was less suitable for the detection of cytotoxic islet cell surface antibodies.