Effect of activin A on the acquisition of M1- and M2-specific markers. (A) MAF, IGF1, SERPINB2, F13A1, and HS3ST1 mRNA expression levels determined by qRT-PCR on macrophages differentiated for 7 days in M-CSF, GM-CSF, or M-CSF plus activin A (10 ng/mL). (B) MAF, IGF1, SERPINB2, F13A1, and HS3ST1 mRNA expression levels determined by qRT-PCR on macrophages differentiated for 7 days in GM-CSF or M-CSF plus GM-CSF–free M1-conditioned medium together with either a blocking anti–activin A antibody (M-CSF + 50% M1 SN + α-ActA) or an isotype-matched antibody (M-CSF + 50% M1 SN + IgG). (C) Expression of the indicated genes in M1 macrophages generated in the presence of a blocking anti–activin A antibody (100 ng/mL) and relative to their expression in M1 macrophages generated in the presence of an isotype-matched antibody (IgG) determined by qRT-PCR using microfluidic cards. The experiment was performed in triplicate and data are presented on a log scale; *P < .005; **P < .05. The left panel shows the expression of M2 (M-CSF)–specific markers, and these results as expressed relative to the level of expression of each gene in the presence of the isotype-matched antibody (Fold induction α-ActA/IgG). The right panel shows the expression of M1 (GM-CSF)–specific markers and these results are expressed relative to the level of expression of each gene in the presence of the anti–activin A antibody (Fold repression, IgG/α-ActA). (D) SERPINE1 mRNA expression levels determined by qRT-PCR on macrophages from 2 independent donors and treated for 7 days with M-CSF, GM-CSF, or activin A. Results are expressed as relative mRNA levels (relative to GAPDH RNA levels) and refer to the expression level observed in the presence of M-CSF (A), M-CSF + 50% M1 SN + IgG (B), or GM-CSF (D). The means and SD of triplicate determinations are shown; *P < .005; **P < .05.