Fig. 3.

Binding of purified IgG to protein C. IgG fractions were prepared from two patients with antiphospholipid antibodies (aPL). IgG (A) showed the binding to β₂-GPI coated on irradiated plates, but IgG (B) did not (data not shown). Both IgG were added to protein C-coated plate with cardiolipin (CL) in the presence/absence of β₂-GPI. IgG (A) with β₂-GPI bound to protein C, but IgG (A) without β₂-GPI, IgG (B) with/without β₂-GPI showed little binding.