FIG 4.

Depletion of neutrophils increases susceptibility to LVS respiratory tularemia. (A and B) BALB/c mice (8 mice/group) were treated i.p. with the neutrophil-depleting 1A8 MAb (A), with the RB6-8C5 MAb (B), or with isotype-matched IgG. Mice were treated either 1 day before and after infection (preinfection) or 3 and 5 days after infection (day 3). The infectious dose was 1 LD₅₀. P values for the significance of the differences between the indicated groups were determined by the log-rank test. *, P < 0.05; **, P < 0.01; ***, P < 0.001. (C and D) BALB/c mice (3 mice/group) were infected i.n. with 1 LD₅₀ of F. tularensis LVS and given i.p. injections of the 1A8 MAb or an isotype-matched IgG. At the indicated time points, lung Gr1-positive CD11b⁺ cells were enumerated by flow cytometry. (C) Representative flow cytometry plots of 1A8- and isotype control-treated lungs; (D) quantification of neutrophils as a percentage of live lung cells. ****, P < 0.001 by two-way ANOVA with a multiple-comparison test comparing means at each time point.