ABSTRACT
The 65 kD isoform of Glutamic Acid Decarboxylase (GAD), is one of the major autoantigens in human type 1 diabetes mellitus. This enzyme shares amino acid identity, in select regions already determined as antigenic with its counterpart from E. coli. We tested the reactivity of diabetic and normal sera and an E. coli GAD-specific monoclonal antibody (2D9) to E. coli GAD by solid phase and competition ELISA, as well as immunoblotting to check for cross-reactivity of autoantibodies to the two antigens. Specific antibodies for E. coli GAD are present in diabetics and normal subjects without any differences in frequency and titer. The reactivity of such antibodies in ELISA could be blocked in a dose-dependent manner by the addition of excess antigen in the liquid phase. Furthermore, the monoclonal antibody against E. coli GAD does not recognise human recombinant GAD65 in an ELISA. We conclude that there is no basis for cross-reactivity between the two antigens, and antibody reactivity to GAD65 in man cannot arise from cross-reactivity to the E. coli enzyme.
Subject(s)
Diabetes Mellitus, Type 1/enzymology , Diabetes Mellitus, Type 1/immunology , Escherichia coli/enzymology , Escherichia coli/immunology , Glutamate Decarboxylase/immunology , Isoenzymes/immunology , Adolescent , Animals , Autoantigens/blood , Autoantigens/immunology , Child , Diabetes Mellitus, Type 1/blood , Diabetes Mellitus, Type 1/diagnosis , Escherichia coli/drug effects , Female , Glutamate Decarboxylase/blood , Glutamate Decarboxylase/pharmacology , Humans , Isoenzymes/blood , Isoenzymes/pharmacology , Male , Mice , Mice, Inbred BALB CABSTRACT
Honey bee venom (HBV) administration to adjuvant arthritic (AA) rats resulted in a significant suppression of arthritis and in suppression of the hepatic acute phase alpha 1-acid glycoprotein (AGP) gene induction at the early stages of disease development. AGP administration in AA rats resulted in acceleration of arthritis development and in increase of severity and duration of the disease. IL-1, IL-6, tumour necrosis factor (TNF) and glucocorticoids alone are not responsible for the HBV-mediated AGP gene down-regulation. These results indicate that AGP gene expression in AA and HBV-treated AA rats involves the interaction of several factors, and that AGP plays a role for AA development in rats.
