Effect of granulocyte colony-stimulating factor on the course of infection with gram-positive bacteria in mice during granulocytopenia induced by sublethal irradiation or cyclophosphamide

This study assesses the effect of granulocyte colony-stimulating factor (G-CSF) on the outcome of infection with Listeria monocytogenes or Staphylococcus aureus in mice during leukocytopenia induced by sublethal total body irradiation or cyclophosphamide treatment. The role of granulocytes during infection was assessed in the thigh muscle, spleen, and liver. G-CSF treatment in naive mice increased the number of blood granulocytes; upon infection, these numbers increased further, but G-CSF did not affect the outgrowth of bacteria in the tissues. Cyclophosphamide treatment and sublethal irradiation decreased the number of blood granulocytes, which was not affected by G-CSF treatment. However, during infection in cyclophosphamide-treated mice, G-CSF increased the number of granulocytes in the circulation and at the site of infection and decreased the number of bacteria in the tissues. Treatment with G-CSF did not affect the number of granulocytes or the course of infection in irradiated mice.