Cxcl1^−/−mice have reduced amplification of early granulocyte precursors in pneumococcal lung infection-induced emergency granulopoiesis. (A-F) WT and Cxcl1^−/− mice were infected intratracheally with S pneumoniae 6303 (5 × 10⁴ CFU). FACS analysis plot (A), percentage (B), and number (per femur/tibia) (C) of hematopoietic stem cells ((c-Kit⁺Sca-1⁺Lin⁻) at 48 hours postinfection. FACS dot plot (D), percentage (E), and number (per femur/tibia) (F) of myeloid progenitor cells (c-Kit⁺Sca-1⁻Lin⁻) at 48 hours postinfection (n = 5-6 mice/infection group; n = 3 mice/control group). All experiments were performed 3 times. Statistical significance was determined by unpaired Student t (B-C,E-F). *P < .05; **P < .01.