Complement-mediated cytotoxic effects of islet cell surface antibodies: factors influencing the sensitivity of the target cells

Sera from 26 out of 34 newly diagnosed type I diabetic patients were cytotoxic to the beta cells of isolated rat pancreatic islet. The severity of beta cell lysis by cytotoxic sera was increased when the islets were preincubated for 20 h with clofibrate, actinomycin D, or tolbutamide. Preincubation of isolated islets with elevated glucose concentration decreased the sensitivity of the beta cells to humoral immune attack whereas glibenclamide had no effect. The sensitivity of target cells to complement-mediated cytotoxicity seems to be related to cellular lipid synthesis.