Depletion of Neutrophils Exacerbates the Early Inflammatory Immune Response in Lungs of Mice Infected with Paracoccidioides brasiliensis

Figure 1

The anti-Ly6G mAb efficiently depleted neutrophils demonstrating their essential role during the early stages of P. brasiliensis infection. BALB/c mice were intranasally inoculated with PBS or P. brasiliensis (Pb18) yeast cells, treated with an isotype control Ab or the anti-Ly6G specific mAb against neutrophils, and analyzed during the acute phase of P. brasiliensis infection (48 h and 96 h after challenge). Neutrophils were assessed by flow cytometry as described in the Materials and Methods section, which were identified as CD45⁺/CD11b⁺/Gr1⁺. (a) Representative flow cytometry contour plots of neutrophils within the gated CD45+ subpopulations are shown. Numbers inside the gates indicate the mean percentages of the gated subsets. (b) Bar plots of the neutrophils per lung. Data shown represent median and IQR (-5 mice/group; representative of two independent experiments). comparing infected-untreated mice versus control mice or comparing infected-anti-Ly6G mAb-treated mice versus infected-untreated mice. (c) BALB/c mice were challenged intranasally with or P. brasiliensis yeast cells, treated as previously described, and evaluated over 12 weeks. Results are representative of two independent experiments (-11 mice/group). A statistically significant difference between the survival plots of the anti-Ly6G and the isotype or untreated mice was determined (). (d) Comparison of fungal burden in the lungs of BALB/c mice infected intranasally with P. brasiliensis yeast cells, treated or not as previously described, and sacrificed at 48 h and 96 h after challenge. Data shown represent median and IQR (-5 mice/group; representative of two independent experiments). A statistically significant increase in fungal burden was observed in the lungs of infected mice treated with the anti-Ly6G mAb () compared to the infected-untreated mice and the infected-isotype control Ab treated mice. PBS, control mice; PBS + Iso, control mice treated with isotype control Ab (clone: 2A3); PBS + antineutrophils, control mice treated with anti-Ly6G mAb (clone: 1A8); Pb18, infected-untreated mice; Pb18 + Iso, infected mice treated with isotype control Ab; Pb18 + antineutrophils, infected mice treated with anti-Ly6G mAb.

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