Figure 1

IL-17A and γδT cells are essential for the control of S. pneumoniae infection. (a–e) Age- and sex-matched WT C57BL/6 or IL-17A-deficient mice were infected i.n with S.p. (5 × 10⁵ CFU: 1 × LD₅₀) (a) Survival of mice was monitored daily (n=10). (b) Number of CFU was determined 60 h post infection (p.i.) in the lungs (left panel) and in the spleen (right panel). Individual counts of one representative experiment out of two (n=7–10) are shown. (c) Absolute number of pulmonary neutrophils was assessed by FACS (CD11b⁺ Ly6G⁺) 12 h p.i. The mean±s.e.m. of one experiment out of two is shown (n=4–5). (d) Absolute number of pulmonary IL-17A-producing lymphocyte subsets was assessed by intracellular FACS staining 12 h p.i. The mean±s.e.m. of two experiments (n=8) is shown. (e) IL-17A⁺ γδT cells from infected mice were screened by FACS for Vγ chain usage 12 h p.i. A pie chart representing means of two experiments is shown (n=6) (left panel). A representative FACS plot of pulmonary γδT cells is presented in the middle panel. CD3^bright vs. CD3^dim γδT cells were labeled in presence or not of the 17D1 mAb (right panel). (f) Means±s.e.m. of CD45⁺ vs. CD45⁻ populations in naive lungs from three experiments (n=6) are represented in the upper panel. A representative FACS plot of γδT cell subsets for anti-CD45 (in vivo) labeling is shown in the lower panel. (g,h) WT and Tcrd^−/− mice were infected with S.p. (5 × 10⁵ CFU). (g) Survival of mice was monitored daily (n=7–8). (h) Number of CFU was determined 60 h p.i. in the lungs and in the spleen (upper panel). Individual counts of two experiments (n=16–17) are shown. Absolute number of neutrophils in lungs of control or S.p.-infected WT or Tcrd^−/− mice (lower panel) was assessed by FACS 12 h p.i. and represented as in panel (c). The mean±s.e.m. of two experiments (n=7–8) is shown. *P<0.05; **P<0.01; ***P<0.001. IL-17, interleukin-17; FACS, fluorescence-activated cell sorting; WT, wild-type.

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