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 Rasheed^1,4, Nadeem A. Ansari², Lokendra Kumar³, Trivendra Tripathi² and Rizwan Ahmad³ and Zafar Rasheed^3,4*

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.