FIG 6.
The cell-permeabilizing activity of CyaA triggers infiltration of neutrophils into B. pertussis-infected lungs. (A and B) BALB/c mice infected intranasally with 105 CFU of the indicated strains were sacrificed on day 6, and the sections of unperfused lung tissue were examined upon NASDCL histochemical and F4/80 immunohistochemical staining for neutrophils and macrophages, respectively. Representative sections documenting the main inflammatory cell components from the B. pertussis-induced lesions are shown. Neutrophil infiltration was significantly reduced in both AC+ Hly− and AC− Hly+ strain-infected lungs, while macrophage counts were reduced only in sections of lungs infected by the AC− Hly+ strain. Magnification, 20×. (B) The numbers of neutrophils and macrophages per surface unit were quantified by analysis of all inflamed parenchyma regions that were manually delimited on three consecutive lung sections for 4 infected animals per group (12 sections analyzed in total). (C to E) Distribution of cell subsets in infected mouse lungs. BALB/c mice were infected with 1.5 × 105 CFU of the various B. pertussis strains (AC+ Hly+, AC− Hly+, AC+ Hly−), using medium as a control, and suspensions of unperfused lungs were analyzed by flow cytometry. (C) Dot plots of cell subtypes in one representative mouse lung suspension per experimental group. (D) Total counts of indicated cell subsets in the infected lungs (n = 5) that were not perfused prior to homogenization. (E) Relative distribution of myeloid cell subsets in suspensions of nonperfused lungs (n = 5). Groups were compared using ANOVA followed by Tukey test for pairwise comparison of subgroups. *, **, and *** represent P values of <0.05, <0.01, and <0.001, respectively. The experiment was repeated twice with similar results. EOS, eosinophils; Mϕ, macrophages; MONO, monocytes; NEU, neutrophils; cDC, conventional dendritic cells; pDC, plasmacytoid dendritic cells.