PMC

Mortality of MSR-A^−/− and MSR-A^+/+ mice after S. aureus challenge. Four MSR-A^−/− and four MSR-A^+/+ mice were injected intraperitoneally with 1 ml of buffer containing S. aureus (Cowan I): (A) 2 × 10⁷ CFU, (B) 2 × 10⁸ CFU, (C) 10⁹ CFU. Mice were observed for signs of systemic infection, and moribund animals were killed. Data represent the mean of six experiments.

Clearance of S. aureus by MSR-A^−/− and MSR-A^+/+ mice. 10⁷ CFU S. aureus (Cowan I) were injected into the peritoneal cavity of four MSR-A^−/− and four MSR-A^+/+ mice. (A) At the indicated times, the peritoneum was lavaged and its content of viable bacteria was determined by plating serial dilutions on agar plates. (B) Viable bacteria in the blood were determined after collecting blood via cardiac puncture of killed animals and subsequent plating on agar plates at the indicated times. Data represent the mean of three experiments.

Recruitment of peritoneal leukocytes. Four MSR-A^−/− mice and four MSR-A^+/+ mice were injected intraperitoneally with 10⁷ CFU of S. aureus (Cowan I). At the indicated times, mice were killed and their peritoneal cavities were irrigated with cold buffer. (A) The total number of leukocytes (WBC) in peritoneal lavage fluids of each mouse was determined microscopically. (B) The total number of neutrophils in the peritoneal lavage fluid was calculated after the percentage of neutrophils was determined microscopically by Wright's stain. Data represent the mean of three experiments.

Phagocytosis of gram-positive bacteria by TMφ from MSR-A^−/− and MSR-A^+/+ mice. Macrophages were prepared, and phagocytosis was measured as described in Materials and Methods. (A) Phagocytosis of various fluorescently labeled gram-positive bacteria and of zymosan particles by TMφ from MSR-A^−/− or MSR-A^+/+ mice. (B) Phagocytosis of various fluorophore-labeled live gram-positive bacteria in serum-free buffer, with or without Ca²⁺, Mg²⁺, or LTA, by TMφ from MSR-A^+/+ mice. (C) Phagocytosis of S. aureus (Cowan I) by TMφ from MSR-A^+/+ mice in the absence or presence of various SR-AI/II ligands: polyguanylic acid (polyG, 0.5 mg/ml), polyinosinic acid (polyI, 0.5 mg/ml), fucoidan (0.5 mg/ml), LTA (1.0 mg/ml), or polycytidylic acid (polyC, 0.5 mg/ml) in the presence of an RNase inhibitor (10 U/ml). (D) Phagocytosis of various gram-positive bacteria and of zymosan particles by TMφ from MSR-A^+/+ mice in the presence of the anti–SR-AI/II antibody 2F8, or an isotype-matched control antibody (EM-34.1). (E) Phagocytosis of S. aureus (Cowan I) by TMφ from MSR-A^+/+ mice in the presence of various concentrations of 2F8 or LTA. All data represent the mean of six to eight experiments.