Capsule-related capture of pneumococci by liver KCs. (A and B) Survival of mice after i.v. infection with 10⁶ CFU of WT TH870 and acapsular mutant (A) or isogenic capsule-switched derivatives (B). n = 5–6. (C) Bacteremia kinetics in the mice during the first 72 h after i.v. infection. n = 5–6. (D) Proportional distribution of isogenic HV and LV pneumococci in blood, liver, and spleen 10 and 30 min after infection. n = 3. (E) Depletion efficiency of neutrophil and monocyte verified by flow cytometry. Mice were treated with 500 μg anti-Ly6G (1A8), 500 μg anti-Ly6C/Ly6G (Gr1), or the isotype controls (ISO). The ratios of neutrophils (Ly6C^low/SSC^high) and inflammatory monocytes (Ly6C^high/SSC^low) in the blood were measured in the myeloid populations (CD45⁺/CD11b⁺). n = 3. (F) Depletion efficiency of tissue-resident macrophage verified by flow cytometry. The Clec4f-DTR mice were treated with 10 ng/g DT. The populations of liver KC and spleen red pulp macrophage (RPM) were measured 24 h after DT treatment. Depletion efficiency was calculated by comparing the ratios of macrophages (CD11b^low/F4/80⁺) in the immune cells (CD45⁺). n = 3. (G) 3D rendering of the liver sinusoid revealing bacterium-binding KCs 20 min after inoculation. (H) Clearance rates of LV isogenic derivatives of TH870 (type 14, 19F, and 23F) during the first 30 min after infection with 10⁶ CFU in Clec4f-DTR mice treated with (+) or without (−) DT. n = 5–10. (I) Sustained bacteremia levels of LV strain TH870¹⁴ in the KC-depleted mice after i.v. infection with 10⁸ CFU. n = 5. (J) In vitro binding of pneumococcal isogenic capsule variants to primary human KCs. n = 3. Mice were used on CD1 (A–D) or C57BL/6 (E–I) backgrounds. Data are representative results (D–G and J) or pooled (A–C, H, and I) from two independent experiments. Two-way ANOVA with Sidak’s multiple comparisons test (H), ordinary one-way ANOVA with Tukey’s multiple comparisons test (J), **, P < 0.01, ***, P < 0.001, ****, P < 0.0001.