Figure 6. Antibody mediated depletion of PMN does not interfere with bacterial clearance in S. pneumoniae infected hosts.

C57Bl/6 mice were intraperitoneally injected with rat IgG (•) as control or RB6-8C5 antibody (○) to deplete PMN. To confirm depletion of PMN, mouse peripheral blood samples were FACS analysed for Gr-1 positive cells on days 1, 2, 5, 6 and 7 post RB6-8C5 antibody treatment. Data show the percentage of Gr-1_high cells out of the respective total granulocyte population for one representative out of two analysed animals per group (A). Likewise, numbers of Gr-1_high/CD11b⁺ cells (neutrophils) in lung tissue or BAL fluid were analysed by flow cytometry 24 h post antibody treatment (B). On the day following antibody treatment, mice were intranasally infected with 1×10⁵ CFU Streptococcus pneumoniae TIGR4 and sacrificed 24 hours after infection to assess S. pneumoniae CFU counts in nasopharyngeal lavage, bronchoalveolar lavage and lung homogenates (C). Additional groups of mice were treated equally to assess CFU counts in nasopharyngeal lavage seven days following infection (C) and survival rates (D). CFU counts show values of individual mice together with group means (horizontal lines). Data are compiled from two independent experiments with groups of at least 5 mice. For lung and BAL fluid neutrophil numbers, data from 5 mice/group are shown (+/−s.e.m.).