Capture of acapsular pneumococci by KCs. (A) Schematic depiction of experimental design to assess the contribution of major phagocytes to the hepatic clearance of acapsular bacteria. (B–E) Bacteremia kinetics (B), clearance rates during the first 30 min (C), proportional distribution at 10 min (D), and bacterial killing in 30 min (E) after i.v. infection of phagocyte-depleted mice with 106 CFU of Δcps. Clec4f-DTR mice were treated with (+DT) or without (−DT) 10 ng/g body weight of DT, and WT mice were treated with 500 μg of each antibody 24 h before i.v. infection. n = 3–5. (F and G) IVM detection of bacterium-binding KCs. Representative IVM images exemplify the KCs (red), pneumococci (green), and sinusoid endothelial cells (cyan) in the liver sinusoids of WT (F) and Clec4f-DTR (G) mice 10 min after i.v. infection with 5 × 107 CFU of pneumococcal strains. n = 3. Five to 10 random fields of IVM images were quantified as bacteria per field of view (FOV) and presented at the right of the images. Scale bar, 20 μm. All mice were used on a C57BL/6 background. Data were representative results (F and G) or pooled (B–E) from two independent experiments. Two-way ANOVA with Tukey’s multiple comparisons test (B), ordinary one-way ANOVA with Tukey’s multiple comparisons test (C and E), *, P < 0.05, ****, P < 0.0001.
