[Inhibition of insulin secretion in vitro by serum of diabetic subjects in the presence of complement].

In order to explore complement-dependent humoral immunity in insulin-dependent diabetic patients, their serum was incubated with Mouse isolated pancreatic islets in the presence of complement, after which the response of these islets to glucose was estimated by measuring insulin secretion. Out of 13 sera from insulin-dependent diabetic patients, 5 caused a significant inhibition of the insulin response. Morphological observation of islets suggested that this inhibition was due to a cytotoxic effect of the sera. In the absence of complement, the same sera were not able to suppress insulin release. No beta-cell inhibition or morphological damage was detectable on islets incubated with sera from 13 healthy subjects and 4 non-insulin dependent diabetic patients, in the presence or in the absence of complement. Complement-dependent humoral immunity may play a role in the beta-cell injury of insulin-dependent diabetes.