Figure 3.

Solid-phase IgM but not IgM in solution activates human blood–derived macrophages to express TF. Human blood–derived macrophages were incubated with IgM, either in solution or adsorbed to the plastic, and analyzed for procoagulant activity and TF expression. A: Solid-phase IgM, but not fluid-phase IgM (10 μg × mL⁻¹), stimulates human blood–derived macrophage procoagulant activity, as measured using a clot turbidity assay. B: Cells were incubated with solid-phase IgM, IgG, or BSA (equal masses) for 24 hours and analyzed for TF mRNA using quantitative PCR. The y axis shows TF (f3, NCBI ccds: 53345.1) mRNA levels normalized to housekeeper (β-actin). Data are mean ± SEM; *P < 0.05 by analysis of variance; n = 5. C: Cells were incubated with solid-phase IgM or fluid-phase IgM and analyzed by flow cytometry for surface TF protein, representative of at least three experiments using different donors.