IL-17A secreted by γδ T cells after MCAO attracts neutrophils to the injured site. (A) Absolute numbers of neutrophils (N; Ly6G⁺, CD11b⁺), macrophages (mφ; Ly6G⁻, CD11b⁺), and dendritic cells (DC; CD11c⁺, CD11b⁺) in ischemic hemispheres of wt, Rag1^−/−, and Tcrd^−/− mice 3 days after MCAO. Cell counts were determined by flow cytometric analysis of CNS-infiltrating cells with the use of TrueCount tubes. The graph shows mean ± SD of 9-12 animals per group analyzed in 4 independent experiments. (B) Immunohistochemical staining of neutrophils (Ly6G) in wt, Rag1^−/−, Tcrd^−/−, and sham-operated wt mice 3 days after MCAO (scale bar = 50 μm). (C) Percentage of neutrophils in the CNS-infiltrating cells of Rag1^−/− mice reconstituted 1 hour before stroke induction with 1 × 10⁷ CD3⁺ cells isolated from wt or Tcrd^−/− mice. (D) Percentage of neutrophils in the CNS-infiltrating cells of Rag1^−/− mice reconstituted 1 hour before stroke induction with 1 × 10⁷ CD3⁺ cells isolated from wt or Il17ra^−/− mice. The graph shows mean ± SD of 6-8 animals per group analyzed in 3 independent experiments. (E) Frequency of neutrophils eluted from the ischemic hemispheres of Rag1^−/− and Il17ra^−/− mice in comparison with wt animals. A representative dot plot displaying gated CD45⁺ cells is shown in the right panel. (F) Percentages of neutrophils in the infiltrating cells of wt animals after administration of 500 μg of anti-IL17A antibodies (MM17F3) 3, 6, and 12 hours or of 500 μg of isotype control antibodies 3 hours after MCAO treatment. Representative plots are shown for isotype control (mouse IgG1) and anti–IL-17A treatment at the indicated time points. The graphs show in all cases the means ± SDs of 9-12 animals per group analyzed 3 days after MCAO in 3 or 4 independent experiments. (A,C,E,F) One-way ANOVA with Bonferroni posthoc test was used to assess statistical significance. **P < .01, ***P < .001. (D) Student t test with *P < .05.