Background: The induction of catalytic antibodies (abzymes) was first postulated by Pauling in 1948. Various catalytic antibodies have been detected recently in the sera of patients with several autoimmune pathologies such as systemic lupus erythematosus and rheumatoid arthritis. In addition, antibodies with DNase and RNase activity have been discovered in the milk and sera of healthy human mothers, which shows the physiologic role of these antibodies. In this study, we examined the proteolytic activity of antibodies in the sera of pregnant women.Methods: IgG antibody fractions were isolated from the sera of 30 healthy pregnant women in the first trimester of pregnancy and 10 control samples (men and nonpregnant women) by subsequent steps of chromatographic purification on Protein G sepharose and sephacryl S-300. All patients were in their first pregnancy and aged 25-35 years. The conditions for proteolytic activity, such as type of buffer, pH and temperature, were optimized. The proteolytic activity of these antibodies was demonstrated by in-gel assay with gelatin as the substrate.Results: Antibody treatments at the optimum temperature showed that some samples from pregnant women contain proteolytic abzymes, as demonstrated by in-gel assays. Western blot results confirmed that the proteolytic activity is an intrinsic property of the antibodies. Conclusions: During pregnancy and immediately after delivery women very often experience autoimmune processes similar to those in patients with autoimmune disease. Because of their specific immune status, pregnant women can produce various catalytic antibodies with different enzymatic activity. These proteolytic abzymes might be involved in the direct clearance of antigens from blood.

Introduction: 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. Material and Methods: 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. Results: 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. Conclusion: 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.