BETA(2)-GLYCOPROTEIN-I REACTIVITY OF MONOCLONAL ANTICARDIOLIPIN ANTIBODIES FROM PATIENTS WITH THE ANTIPHOSPHOLIPID-SYNDROME

Objective. To elucidate the specificity of anticardiolipin antibodies (aCL) from patients with the antiphospholipid syndrome (APS) to variou s phospholipids (PLs), DNA, and beta(2)-glycoprotein I (beta(2)-GPI). Methods. Five monoclonal aCL were established from peripheral blood ly mphocytes of 3 patients with the APS. The reactivity of monoclonal aCL with various PLs, with DNA, and with beta(2)-GPI was examined by enzy me-linked immunosorbent assay (ELISA). Results. All of the monoclonal aCL bound to anionic PLs, only in the presence of beta(2)-GPI. Neither monoclonal aCL nor beta(2)-GPI bound to DNA. Monoclonal aCL bound to solid-phase beta(2)-GPI on polystyrene ELISA plates that had carboxyl groups on their surface, but did not react with solid-phase beta(2)-GP I on ordinary polystyrene plates. A mixture of beta(2)-GPI and CL inhi bited the binding of monoclonal aCL to beta(2)-GPI, but CL or beta(2)- GPI alone did not. Conclusion. Monoclonal aCL may recognize a cryptic epitope, which appears as a result of beta(2)-GPI binding to anionic P Ls or to polystyrene with carboxyl groups.