African Journal of Immunology Research

African Journal of Immunology Research ISSN 9431-5833 Vol. 7 (3), pp. 001-010, March, 2020. © International Scholars Journals

Full Length Research Paper

Autoantibodies against reactive oxygen species modified immunoglobulin G in patients with type 1 diabetes mellitus

Naila Rasheed1,4, Nadeem A. Ansari2, Lokendra Kumar3, Trivendra Tripathi2 and Rizwan Ahmad3 and Zafar Rasheed3,4*

1Division of Pharmacology, Central Drug Research Institute, Lucknow, India.

2Department of Biochemistry, Faculty of Medicine, J. N. Medical College, A.M.U., Aligarh, India.

3Department of Biochemistry, SBSPGI, Balawala, Dehradun, India.

4Department of Medical Biochemistry, College of Medicine, Qassim University, P.O. Box 6655, Buraidah-51452, KSA.

Accepted 16 October, 2019

Abstract

The role of hydroxyl radicals (.OH) damaged immunoglobulin G (IgG) in insulin dependent diabetes mellitus has been investigated. IgG was isolated from normal human serum and modified by hydroxyl radicals, generated by UV irradiation of hydrogen peroxide. .OH-induced modification on IgG has been studied by ultra-violet (UV) absorption spectroscopy, tryptophan/tyrosine fluorescence, circular dichrosim, SDS-PAGE and carbonyl groups estimations. .OH caused extensive damage to IgG. The binding characteristics of circulating antibodies in type 1 diabetes patients against native and modified IgG were assessed. Type 1 diabetes patients (n = 36) were examined by direct binding ELISA and the results were compared with healthy age-matched controls (n = 22). High degree of specific binding of diabetes sera towards .OH modified IgG, in comparison to its native analogue (p < 0.05). Sera from normal human subjects showed negligible binding with either antigen. Our results conclude that .OH-modification of IgG causes structural perturbations, resulting in the generation of neo-epitopes and making it a potential immunogen. IgG modified with .OH may be one of the factors for the induction of circulating type 1 diabetes autoantibodies.

Key words: Autoantibodies, hydroxyl radicals, immunoglobulin G, .OH-IgG, type 1 diabetes mellitus.