To confirm that BALF TNF responses reflected alveolar macrophage interactions with S. pneumoniae and to try and reduce CFU differences between the strains, low-dose infection (5 × 105 CFU) experiments were performed in mice treated with intranasal liposomal clodronate 72 h prior to infection, which depletes approximately 85% of alveolar macrophages (32). Here, TNF is linked to infection.