TNF is required for IL-17–induced neutrophil influx in the lungs. (A) Cells in BALF were quantified 8 hours after intranasal treatment of mice with PBS or rmIL-17 (10 μg). Wild-type mice (PBS, n = 5; IL-17, n = 4) and TNF^−/− mice (PBS, n = 5; IL-17, n = 4). Data are the average + SD of results pooled from 2 independent experiments, each of which gave similar results. *P < .01 versus corresponding values for PBS-treated mice; †P < .01 versus corresponding values for IL-17–treated wild-type mice. (B) TNF levels in culture supernatants of BMCMCs that were stimulated with ionomycin in the presence of various concentration of rmIL-17 for 6 hours. Data are the average ± SD of triplicate determinations in 1 of 3 independent experiments, all of which gave similar results (because the SDs were very small, the bars indicating the SDs are obscured by the symbols). *P < .01 versus corresponding values for the cells incubated without rmIL-17 (0 ng/mL).