CXCL1 and infection: Upon infection of Il13−/− and WT mice with S. pneumoniae, we observed a more pronounced early (6 hr) influx of neutrophils in bronchoalveolar lavage fluid (BALF) and lung (Figures 4E and 4F) and enhanced amounts of lung CXCL1 (Figure 4G) in Il13−/− mice.