FIGURE 2.

Kaplan–Meier survival curves after intracerebral injection of different numbers of Streptococcus pneumoniae D39 (kindly provided by Prof. Dr. Sven Hammerschmidt, University of Greifswald, Germany). (A) C57Bl/6 immunocompetent mice, (B) C57Bl/6 mice rendered neutropenic with 50 μg of an anti-Ly-6G monoclonal antibody (1A8 clone). Meningitis was induced by bacterial inoculation into the right frontal neocortex under anesthesia. Please note that 70% of immunocompetent mice survived an intracerebral injection of 200 colony-forming units (CFU). Conversely, all neutropenic mice were killed by an intracerebral inoculum of 100 CFU in less than 3 days suggesting that microglia need the cross-talk with granulocytes across the blood–brain barrier to function properly (Sandra Ribes, unpublished data).