Bacterial clearance of pneumococci from noninfluenza-infected lungs after coinoculation of serum from normal, unvaccinated mice (NMS) or serum from mice vaccinated with PPS-conjugate (IMS). A, Bacterial colony-forming units (CFUs) were determined 4 hours after inoculation of C57Bl/6 mice with 105 (Groups 1 and 2) or 106 (Groups 3 and 4) CFUs of A66.1 S. pneumoniae and NMS or IMS. B, Numbers of bacterial CFUs 4 hours after inoculation of C57Bl/6 WT or FcγR−/− mice with 106 CFUs of A66.1 S. pneumoniae and IMS. Each symbol represents an individual mouse (4–5 mice/group). The data represent results from at least 2 independent experiments. **P < .01; ****P < .0001. Abbreviations: NS, not significant; PPS, pneumococcal polysaccharide.