Avidity of anti-beta-2-glycoprotein I antibodies.
The terms affinity and avidity are often used indiscriminately, despite clearly differing. Since affinity refers to monovalent binding of antibodies to a monovalent epitope, the majority of data on the binding of anti-beta2-glycoprotein I antibodies (anti-beta2-GPI) characterized their avidity rather than affinity. Anti-beta2-GPI were generally believed to be of low avidity, but heterogeneous avidity of patients' IgG anti-beta2-GPI has been demonstrated. High avidity anti-beta2-GPI monoclonals were reported to possess higher pathogenicity than low avidity anti-beta2-GPI. Polyclonal high avidity anti-beta2-GPI were found to be more common in patients with antiphospholipid syndrome (APS) and associated with thrombosis. Some conformational changes of beta2-GPI are required for the binding of polyclonal anti-beta2-GPI to the antigen: neither high density of the antigen nor high avidity of the anti-beta2-GPI alone is sufficient for the recognition. Avidity of anti-beta2-GPI should be considered in any attempt of inter-laboratory standardisation and/or evaluation of anti-beta2-GPI enzyme-linked immunosorbent assay (ELISA).
University Medical Centre, Division of Internal Medicine, Department of Rheumatology, Vodnikova 62, SI-1000, Ljubljana, Slovenia. borut.bozic@guest.arnes.si
B
B
Bozic
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S
Cucnik
T
T
Kveder
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B
Rozman
D000818:Animals; D000915:Antibody Affinity / Q000235:genetics; D001323:Autoantibodies / Q000737:chemistry* / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D006023:Glycoproteins / Q000235:genetics / Q000276:immunology*; D006801:Humans; D053482:beta 2-Glycoprotein I
D001323:Autoantibodies; D006023:Glycoproteins; D053482:beta 2-Glycoprotein I