Immunoglobulin Classes and Light Chain types of Antiinsulin Antibodies in Insulin Autoimmune Syndrome

Abstract

In 6 patients with insulin autoimmune sy ndrome (IAS), classes of immunoglobulins and types of their light chains were studied by radioimmunoelectrophoresis, Christiansen's method and specific precipitation. Two of 6 patients had been treated with thiamazole because of association with Graves' disease, and developed hypoglycemia caused by autoimmunity to insulin. Another 4 showed hypoglycemic attacks without Graves' disease. For the control study, serum samples were obtained from 13 diabetics treated with insulin.
The results obtained are as follows:
Classes of immunoglobulins: Anti-insulin antibodies were found to be only in immunoglobulin G (IgG) both in patients with IAS and diabetics treated with insulin by radioimmunoelectrophoresis and specific precicipitation. By Christiansen's method, however, besides IgG, the antibodies were detected in IgM in 2 insulin-treated diabetics.
Types of light chains of immunoglobulins: Insuln-treated diabetics showed both K-and L-types of light chains by radioimmuno electtophoresis and specific precipitation. In 3 patients among 6 with IAS, the serum samples were obtained shortly after onset of hypoglycemic attack. In these 3 patients, a minimal amount of the L-type was found by specific precipitation besides the K-type. Therefore, the ratio of K to L-type (K/L) was much higher in these 3 patients than in the diabetics treated with insulin. Regarding the remaining 3 with IAS, only K-type was present.
As a conclusion, one of the structual differences of antibodies to insulin was observed in the light ckains of the immunoglobulins between the patients with IAS and those treated with insulin.