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Figure 2 | BMC Immunology

Figure 2

From: Platelets convert peripheral blood circulating monocytes to regulatory cells via immunoglobulin G and activating-type Fcγ receptors

Figure 2

FcγRs mediate IgG-bound platelet-induced regulatory response in human peripheral blood circulating monocytes. (A) PBMCs were stimulated with LPS in the presence of whole IgG of an anti-CD41 mAb or an equimolar amount of the F(ab’)2 fragment, and then the production of IL-10 and IL-1β was measured after 24 h. Blank (−) indicates cells with no antibody or stimulator for monitoring spontaneous production of cytokines. Data are shown as means for triplicate samples ± SEM. The results are representative of more than three independent experiments with similar results. *P < 0.05; **P < 0.01; n.s., not significant. (B) FcγRII mediates IgG-bound platelet-induced regulatory response. PBMCs were incubated with an FcγRIIA/B-blocking mAb (IV.3), and then stimulated with LPS in the presence of an anti-CD61 or anti-CD41 mAb or its cIg. Data are shown as means for triplicate samples ± SEM. The results are representative of more than three independent experiments with similar results. *P < 0.05; **P < 0.01. (C) Robust FcγRIIA/B expression on circulating CD14++CD16 and CD14+CD16+ monocytes. The monocytes were sort-purified from human PBMCs and tested for their CD32 (FcγRIIA/B) expression. (D) Sorted CD14++CD16 and CD14+CD16+ monocytes were treated with an anti-CD61 mAb in the presence of CD32 (FcγRIIA/B)- or CD16 (FcγRIIIA/B)-blocking mAb, IV.3 or 3G8, respectively, or an isotype control, and then stimulated with LPS in the presence of human platelets. The IL-10 and IL-12 levels in the culture supernatants were measured after 24 h. Data are shown as means for triplicate samples ± SEM. The results are representative of more than three independent experiments with similar results. *P < 0.05; **P < 0.01; n.s., not significant.

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