The orally active PDE4 inhibitors roflumilast and CDP840, given either as a single dose or regularly are known to inhibit the allergen-induced LAR and AHR [29-31], and rolfumilast has been shown to reduce sputum eosinophil and neutrophils in subjects with COPD [32]. This evidence concerns the gene PDE4A and chronic obstructive pulmonary disease.