Groups of eight mice were treated with either 350 μg of rat anti-mouse Ly6G or rat IgG2a isotype control, one and two days prior to pneumococcal challenge (a, b), or with anti-IL-17A or mouse IgG1 isotype control (c, d), one day before, 2 h before and 6 h after intranasal challenge (see “Methods” section). Twenty-four hours of post-infection, numbers of pneumococci in the nasopharynx and lungs were quantitated (see “Methods” section). NB: n is <8 for some groups because some mice didn’t survive the challenge procedure, or until the time of harvest. Viable counts (total CFU per tissue) are shown for each mouse at each site; horizontal bars indicate the geometric mean (GM) CFU for each group; the broken line indicates the threshold for detection. Differences in GM bacterial loads between groups are indicated by asterisks: *p < 0.05, **p < 0.01, ***p < 0.001, by unpaired t-test.