title: Autoimmune reactivity of IgM acquired after oxidation.
abstract: OBJECTIVE
  Redox-reactive antibodies, mainly of the IgG class, gained a wide area of interest after their autoimmune reactivity was revealed following the application of chemical and physiological oxidants. In this study, we examined the susceptibility of IgMs to oxidation and evaluated their binding to the autoantigens important in some autoimmune diseases.
  
  
  METHODS
  IgM and IgG fractions, isolated from healthy individuals' sera, were oxidized using direct electric current or physiological oxidant hemin. Specificities towards beta-2-glycoprotein I (β(2)-GPI), cardiolipin (CL), and rheumatoid factor were evaluated with the enzyme-linked immunosorbent assays (ELISAs). Post-translational modification was investigated by 2,4-dinitrophenylhydrazine reaction.
  
  
  RESULTS
  Electrochemically oxidized IgM fractions exhibited altered immunoreactivity - low to medium titers in anti-CL and low positive titers in anti-β(2)-GPI ELISA but exhibited no rheumatoid factor reactivity. Oxidized IgG and IgM fractions exhibited 2.5- and 5-fold increase in the carbonyl content, respectively.
  
  
  CONCLUSIONS
  An increase in the carbonyl content along with increased immunoreactivity after oxidation suggests modifications of the IgM paratopes. These results point towards possible modifications of native IgMs to their autoimmune state despite the fact that IgMs were less susceptible to oxidation than IgGs. The importance of an individual's redox status in maintenance of autoimmune reactions was emphasized by in vitro diagnostic tests.
authors.affiliation: University in Ljubljana, Ljubljana, Slovenia.
authors.forename: Jasna
authors.initials: J
authors.lastname: Omersel
authors.forename: Ivica
authors.initials: I
authors.lastname: Avberšek-Lužnik
authors.forename: Pegi Ahlin
authors.initials: PA
authors.lastname: Grabnar
authors.forename: Tanja
authors.initials: T
authors.lastname: Kveder
authors.forename: Blaž
authors.initials: B
authors.lastname: Rozman
authors.forename: Borut
authors.initials: B
authors.lastname: Božič
mesh_terms: D000328:Adult; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D001324:Autoantigens / Q000276:immunology* / Q000378:metabolism; D001666:Binding Sites, Antibody; D002308:Cardiolipins / Q000276:immunology; D004563:Electrochemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006427:Hemin / Q000494:pharmacology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology / Q000378:metabolism; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology* / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010659:Phenylhydrazines / Q000378:metabolism; D050050:Protein Carbonylation; D011499:Protein Processing, Post-Translational; D012217:Rheumatoid Factor / Q000276:immunology; D053482:beta 2-Glycoprotein I / Q000276:immunology
chemical_list: D001324:Autoantigens; D002308:Cardiolipins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D010659:Phenylhydrazines; D053482:beta 2-Glycoprotein I; C004787:2,4-dinitrophenylhydrazine; D006427:Hemin; D012217:Rheumatoid Factor