Cellular cytotoxicity to membrane-associated insulin in an autologous system.

A method is described for the measurement of T-cell cytotoxicity to purified preparations of insulin, their high molecular weight fractions and C-peptide derivatives. The technique assesses cellular cytotoxicity to membrane associated insulin in an autologous system. Peripheral blood lymphocytes from 19 type 1 diabetic patients were stimulated in vitro for 6 days with the pharmaceutical preparation(s) used therapeutically. At the end of this period, they were set up in a 4-h cytotoxicity assay against 51Cr labelled PHA blast transformed lymphocytes in the presence of therapeutic insulin, monocomponent insulin, B-component or C-peptide. The results presented here demonstrate cytotoxicity to insulin B-component in diabetic patients who have received pork insulin for 2-6 years. The possible reasons for this finding are discussed.