To examine whether the differential effects of these IgG may be explained by their binding to different epitopes of the FXa active site, we compared the effects of APS-IgG, SLE-IgG and a 50/50 mix of these upon FXa activity to examine whether an appreciable increase in ability to inhibit FXa activity would be observed with the mixed APS/SLE-IgG samples. Here, F10 is linked to systemic lupus erythematosus.