(A) Protocol: BALB/c mice were placed on a vitamin D supplementation or control water for 4 weeks, and then exposed intratracheally to saline, DEP (100μg) and/or house dust mite (HDM; 10μg) three times a week over 3 weeks. (B) Airway Resistance was measured 24 hours after last challenge. (n=4–12 mice per group; 2-way ANOVA, ****p< 0.0001, ***p <.001, **p <.01, *p < 0.05). (C) Resistance after exposure to 12.5 mg/mL methacholine. (D) Total lung cell counts. (E) BALF cell counts. (F) BALF eosinophils. (G) BALF neutrophils.