Fig. 1.

Importance of β2-glycoprotein 1 (GPI) in antibody binding to antigens. Enzyme-linked immunosorbent assay (ELISA) of immunoglobulin (Ig)M anti-cardiolipin (CL) (a) and IgM anti-oxidized (Ox)CL (b) and dependency of β2-GPI in sera from uraemic patients [haemodialysis (HD) patients], patients with the anti-phospholipid antibody syndrome and healthy controls (a), who had been incubated with different concentration of β2-GP1 [for 1 h at room temperature (RT)]. β2-GPI increased anti-CL binding to CL but not anti-OxCL binding to OxCL among patients with anti-phospholipid antibody syndrome. The effect of anti-CL among uraemics was intermediate, while anti-CL in sera from healthy controls was β2GPI-independent. Antibody levels were determined by ELISA, and the optical density (OD) value where no β2GPI was added was set at 1 as a standard. The results are expressed as mean ± standard deviation.