Anticardiolipin antibodies (aCL) derived from the sera of individuals exhibiting the antiphospholipid syndrome (APS) directly bind to β2- glycoprotein I (β2-GPI), which is adsorbed to an oxidized polystyrene surface. Oxygen atoms were introduced on a polystyrene surface by irradiation with electron or γ-ray radiation. X-ray photoelectron spectroscopy revealed the irradiated surfaces were oxidized to generate C-O and C=O moieties. aCL derived from either APS patients or (NZW x BXSB)F1 mice bound to β2-GPI coated on the irradiated plates, depending on the radiation dose. Antibody binding to β2-GPI on the irradiated plates was competitively inhibited by simultaneous addition of cardiolipin (CL)-coated latex beads mixed together with β2-GPI but were unaffected by addition of excess β2-GPI, CL micelles, or CL-coated latex beads alone. There was a high correlation between binding values of aCL in sera from 40 APS patients obtained by the anti-β2-GPI enzyme-linked immunosorbent assay (ELISA) using the irradiated plates and those by the β2-GPI-dependent aCL ELISA. Therefore, aCL have specificity for an epitope on β2-GPI. This epitope is expressed by a conformational change occurring when β2-GPI interacts with an oxygen- substituted solid phase surface.
ASJC Scopus subject areas
- Immunology and Allergy