title: Naturally occurring V region connected antibodies inhibit anti-dsDNA antibody reactivity with dsDNA.
abstract: The production of autoantibodies against a vast array of self antigens, most notably double stranded (ds) DNA, characterized systemic lupus erythematosus (SLE). The purpose of this work is to study specific Ig fractions isolated from normal human serum (NHS) and their effect on the binding of anti-double-stranded deoxyribonucleic acid (dsDNA) antibodies (Abs) to dsDNA. A fraction named immunoglobulin G (IgG)-reactive IgG was purified from total NHS IgG by absorption onto (CNBr)-activated Sepharose 4B linked to intact IgG molecules (IgG-Sepharose column). IgG-reactive IgG was co-incubated with systemic lupus erythematosus (SLE) patient's serum and binding of the anti-dsDNA Abs to dsDNA was measured by enzyme-linked immunosorbent assay (ELISA). Co-incubation of SLE patient's serum with IgG-reactive IgG resulted in a dose-dependent reduction in binding of anti-dsDNA Abs to dsDNA. A reduction greater than 70% was observed at a concentration of 300 μg of IgG-reactive IgG per mL of a 400-fold diluted SLE patient's serum whereas total NHS IgG, at the same concentration, resulted in a 10% reduction in binding. The purification process used to isolate IgG-reactive IgG was based on interactions between intact Ig rather than on interactions between F(ab')(2) portions. IgG(2) is the predominant immunoglobulin (Ig) subclass in IgG-reactive IgG. Thus, IgG(2) might have an important role in the connectivity characteristics of NHS IgG. The capacity of IgG-reactive IgG to inhibit anti-DNA Ab binding to dsDNA may have potential application in the treatment of SLE. This targeted biological approach may provide an alternative strategy to immunosuppressants.
authors.affiliation: Department of Experimental Oncology, Institute of Oncology and Radiology of Serbia, Pasterova 14, 11000 Belgrade, Serbia. tsrdic@yahoo.com
authors.forename: Tatjana
authors.initials: T
authors.lastname: Srdic-Rajic
authors.forename: Vladimir
authors.initials: V
authors.lastname: Jurisic
authors.forename: Sladjana
authors.initials: S
authors.lastname: Andrejevic
authors.forename: Branka
authors.initials: B
authors.lastname: Bonaci-Nikolic
authors.forename: Timothy
authors.initials: T
authors.lastname: Bowker
authors.forename: Daniela
authors.initials: D
authors.lastname: Concas
authors.forename: Radmila
authors.initials: R
authors.lastname: Metlas
mesh_terms: D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000097:blood* / Q000276:immunology; D000974:Antibodies, Antinuclear / Q000097:blood* / Q000276:immunology; D000918:Antibody Specificity; D001324:Autoantigens / Q000097:blood* / Q000276:immunology; D001665:Binding Sites; D001667:Binding, Competitive; D002846:Chromatography, Affinity; D004247:DNA / Q000097:blood* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000737:chemistry / Q000276:immunology; D007167:Immunotherapy / Q000379:methods*; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000188:drug therapy / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011485:Protein Binding / Q000276:immunology; D012685:Sepharose / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000974:Antibodies, Antinuclear; D001324:Autoantigens; D007074:Immunoglobulin G; C036210:immunoglobulin G-sepharose; D004247:DNA; D012685:Sepharose