The Presence of Insulin Catalytic Antibodies in Plasma of Two Type 2 Diabetes Patients

Recent studies have reported the role of catalytic antibodies in the pathogenesis pattern of some diseases. Autoimmune reactions playing a role in some type 2 diabetic patients and the β- cell autoimmune markers were found to be present in some of these patients. The presence of such antibodies was assessed in the plasma of patients suffering from type 2diabetes. Antibodies in 3 diabetic patients and 7 non-diabetic control subjects were purified using protein-G sepharose affinity column chromatography and S-300 gel filtration methods purity of the IgG antibodies was confirmed by SDS-PAGE and in western blot analysis and proteolytic activity of electrophoretically homogenous IgG antibodies was confirmed with zymogram analysis. The purified antibodies were incubated with insulin at 37°C for 6 days and the effect of antibodies on insulin degradation was assessed by Acetic Acid-Urea polyacrylamide gel electrophoresis. Insulin degradation effect was observed only in purified antibodies in the 2 diabetic patients and it was not seen in the 7 control subjects and the remaining diabetic patients. Our data revealed, for the first time, insulin degradation by isolated IgG from 2 diabetic patients. This finding may not only explain the insulin resistance observed in some diabetic patients, but may most likely propose also a new mechanism for occurrence of the disease.