FIGURE 1.

PMNs from old mice fail to efficiently kill Streptococcus pneumoniae. PMNs were isolated either from the bone marrow or blood of young (2 month) and old (18‐22 month) C57BL/6 mice and infected with S. pneumoniae pre‐opsonized with sera from the same mouse group for 45 min at 37°C. Reactions were stopped on ice, and viable CFU were determined after serial dilution and plating. The percentage of bacteria killed upon incubation with PMNs was determined by comparing surviving CFU to a no PMN control. Data shown are pooled from three separate experiments (n = 3 biological replicates or mice per strain) where each condition was tested in triplicate (n = 3 technical replicates) per experiment. *Significant differences calculated by one‐way ANOVA followed by Tukey's test