Figure 3.

Proinflammatory cytokine production in response to S. pneumoniae in control and FcγRIIb^−/− mice. (A) Peritoneal macrophages from C57BL/6 and FcγRIIb^−/− mice were cultured for 12 h alone, with unopsonized, heat-killed S. pneumoniae, or with heat-killed S. pneumoniae opsonized with heat-inactivated immune serum. TNF-α levels, measured using a cytometric bead assay, and were higher in FcγRIIb^−/− culture supernatant in all conditions, but particularly when opsonized bacteria were used. The experiment shown is representative of two. (B) Serum TNF-α levels were higher in FcγRIIb^−/− mice whether unimmunized (left), 7 h after inoculation with S. pneumoniae (middle), and in particular, in mice immunized and subsequently inoculated with S. pneumoniae (right, gray shading). (C) IL-6 levels in peritoneal macrophage culture supernatant. (D) Serum IL-6 levels in control (□) and FcγRIIb^−/− (▪) mice, uninfected or 7 h after inoculation with S. pneumoniae either with (gray shading) or without prior immunization. Values are from individual mice, experiments shown are representative of two, and p-values were obtained using an unpaired Student's t test.