On the Occurrence of the Diabetes-Associated Antigen GAD 65 in Human Sera

Abstract

Background: Glutamic acid decarboxylase (GAD 65) is involved as an antigen in diabetes mellitus type 1 and is generally considered to be located intracellularly in pancreas β-cells. In this study we demonstrate its appearance in 64 human sera samples representing a cross-section of a blood bank. Method: The proof of GAD 65 in sera was done using an enzyme-linked immunosorbent assay (ELISA) setup where it was detected by interaction with corresponding antibodies labeled with an enzyme. The enzyme catalyzes a substrate reaction, resulting in a change of color, that is used for the quantitative evaluation of the antigen-antibody interaction. Result: The measurements showed that GAD 65 exists in various amounts in the sera of blood donors, with an average concentration of 58.00 ng/ml. The correlation analysis of samples stored at –80°C and at room temperature demonstrates the stability of GAD 65 at room temperature. The correlation coefficient between the GAD 65 concentrations of samples stored at room temperature and of the same samples after 1 week shows that the molecule remains stable. Conclusion: Our results encourage us to propose antigen GAD 65, due to its frequency in human sera in different concentrations and its stability, as a biomarker for the early diagnosis of type 1 diabetes and related inflammations.

Low Frequencies of Autoimmunity-Associated <b><i>PTPN22</i></b> Polymorphisms in MODY Patients, Including Those Transiently Expressing Islet Cell Autoantibodies

“…Circulating GAD antigen identified in the blood serum of randomly chosen blood donors as published in this journal [55] may also be elevated and thus available for antigen-presenting cells before and during diabetes onset as a consequence of β-cell destruction. Further research should elucidate the mechanisms that lead to the transient exposure of β-cell antigens to the immune system in at least a portion of the MODY patients of Central European origin.…”

The Role of the Antigen GAD 65 in Diabetes Mellitus Type 1: A Molecular Analysis

“…But this hypothesis can not explain the procedure of immunization and therefore the occurrence of GAD 65 antibodies in the blood. To understand the procedure and development of immunization, it was proposed that in an initial step the immune system is primed by the accessibility to GAD 65 [36,37]. The assumption is that the enzyme has to be in the human serum and should be found in higher concentrations before the onset of the disease.…”