TLR2 is required for SAA-induced neutrophilia in mice. (A) SAA was injected subcutaneously into age- and sex-matched C57BL/6 and Tlr2^−/− mice (n = 7). The plasma concentration of G-CSF was determined at the end of the study (168 hours). (B) SAA was injected into these mice as in panel A. Blood samples were collected before injection (0 hours) and at 48, 120, and 168 hours after the initial injection. Neutrophil counts in the whole blood were obtained from WBC differential counts and presented as fold changes. *P < .05 compared with WT mice. In both types of mice, there is a significant difference (P < .05) between 0 hours and other time points in all panels.