Figure 6. Effect of rPF4 on phagocytosis of live S. aureus by macrophages.

Nonencapsulated and encapsulated bacteria were preincubated with 40 μg/ml rPF4 for 1 h at 37 °C. 1×10⁶ CFUs of bacteria were added to adherent inflammatory peritoneal macrophages (5×10⁴) and incubated for 1 h at 37 °C. Aliquots of media containing nonphagocytosed bacteria were plated on LB agar for 16 h at 37 °C to determine CFU/ml. Phagocytosis was assessed as a difference between total added and nonphagocytosed bacteria. Data are expressed as a percent of phagocytosed bacteria and are means ± S.D. of three experiments. ***p< 0.001, ns, no significant difference. (B) Adherent inflammatory macrophages isolated from WT and Mac-1-deficient mice were incubated with nonencapsulated S. aureus pretreated with 40 μg/ml rPF4 for 1 h at 37 °C. Data are expressed as a percent of phagocytosed bacteria and are means ± S.D. of three experiments with duplicates. **p≤ 0.01, ns, no significant difference.