Mast cell–derived TNF, but not T-cell–derived TNF, contributes to Th17 cell–mediated neutrophilic airway inflammation. (A-B) Mice were treated with 50 μg of OVA or PBS intranasally for 3 days (once per day). Cells (A) and cytokine levels (B) in BALF were quantified 24 hours after the last inhalation of OVA. Kit^+/+ and wild-type OTII mice (PBS, n = 11; OVA, n = 15), Kit^W-sh/W-sh OTII mice (PBS, n = 13; OVA, n = 18), Kit^W-sh/W-sh OTII mice that were systemically engrafted with wild-type BMCMCs (Kit^W-sh/W-sh OTII + WT BMCMCs) (PBS, n = 5; OVA, n = 11), TNF^−/− OTII mice (PBS, n = 9; OVA, n = 15) and Kit^W-sh/W-sh OTII mice that were systemically engrafted with TNF^−/− BMCMCs (Kit^W-sh/W-sh OTII + TNF^−/− BMCMCs) (PBS, n = 6; OVA, n = 11) (A-B). Data are the average + SD of results pooled from 3 independent experiments, all of which gave similar results. *P < .01 versus corresponding values for PBS-treated mice; †P < .05 versus corresponding values for each of the 3 other OVA-treated groups; ¶P < .01 versus corresponding values for OVA-treated Kit^+/+ and wild-type OTII mice and Kit^W-sh/W-sh OTII mice plus WT BMCMCs; and §P < .05 versus corresponding values for OVA-treated TNF^−/− OTII mice. (C) Rag-1^−/− mice were injected intravenously with wild-type (WT), TNF^−/−, or IL-17^−/− OTII CD4⁺ T cells, and then the mice were treated with 50 μg of OVA or PBS intranasally for 3 days (once per day). Cells in BALF were quantified 24 hours after the last inhalation. WT OTII CD4⁺ T-cell–injected Rag-1^−/− mice (PBS, n = 6; OVA, n = 10), TNF^−/− OTII CD4⁺ T-cell–injected Rag-1^−/− mice (PBS, n = 6; OVA, n = 10), and IL-17^−/− OTII CD4⁺ T-cell–injected Rag-1^−/− mice (PBS, n = 6; OVA, n = 8). 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 < .05 versus corresponding values for OVA-treated WT OTII CD4⁺ T-cell–injected Rag-1^−/− mice or TNF^−/− OTII CD4⁺ T-cell–injected Rag-1^−/− mice.