Phagocyte infiltration into pulmonary metastases of WT and Mac-1^−/− mice.

WT and Mac-1^−/− mice were challenged intravenously with 1 × 10⁵ B16F10 cells, and treated with peg–G-CSF and saline (control), or TA99 and peg–G-CSF as detailed in “Materials and methods.” Lungs were removed 15 days after tumor inoculation for immunohistochemistry. GR-1 staining (mouse neutrophil marker, shown in brown) of pulmonary tissue of WT (left panels) and Mac-1^−/− (right panels) mice treated with (bottom panels) or without (top panels) TA99. Red arrows point at GR-1–positive cells. Original magnifications: × 400 (main panels) and × 1000 (insets).