Effect of Immune Complexes on Macrophage Subsets Figure 6. mRNA expression of IL-10, IL-23p19, and IL-12p35 after macrophage stimulation with HAGGs and LPS. Healthy peripheral blood monocytes were cultured for 4 days in medium or in medium supplemented with IFN-c, IL-4, or IL-10. Polarized macrophages were stimulated for 7 hours with LPS, in the presence or absence of HAGGs. mRNA expression levels were measured by quantitative RT-PCR and were normalized to those of the human housekeeping gene GAPDH. Bars represent the mean 6 SEM of 6 independent experiments. *p,0.05. doi:10.1371/journal.pone.0035994.g006 Discussion ICs in combination with TLR ligands have been described to increase the IL-10 production of mouse macrophages, leading to a distinct alternative macrophage activation type (M2b) [5]. ICs also stimulated the in vivo IL-10 production in different animal models, which induced immune regulation [34,38]. In host defence, this mechanism could represent a physiological feed-back loop, Figure 7. TNF, IL-6, and IL-10 production by MWIFN-c, MWIL-4, and MWIL-10 after stimulation with immobilized IgG and P3C. Healthy peripheral blood monocytes were cultured for 4 days in medium or in medium supplemented with IFN-c, IL-4, or IL-10. Polarized macrophages were not stimulated, or stimulated for 20 hours with P3C, in the presence or absence of immobilized IgG. Bars represent the mean 6 SEM of 3 independent experiments. *p,0.05, **p,0.01, ***p,0.001. doi:10.1371/journal.pone.0035994.g007 PLoS ONE | www.plosone.org 7 April 2012 | Volume 7 | Issue 4 | e35994