Dose dependence of APS IgG-induced monocyte TF activity. Normal monocytes were incubated with varying concentrations of APS IgG or normal IgG for 6 hours in the presence of β2GPI (100 μg/mL), washed, and assayed for TF activity. Scaling of the x-axis, IgG concentration, is logarithmic. Data shown are the mean ± SEM of 2 experiments.