In CF, it is degraded by neutrophil elastase, which is present in high concentrations in the sputum and is ineffective at ASL pH values below 7.0 [19,24], also leading to reduced activity of Gram-negative bacteria, such as Haemophilus influenzae, Pseudomonas aeruginosa and the Burkholderia cepacia family, in CF airways [23]. This evidence concerns the gene ELANE and cystic fibrosis.