The airways of cystic fibrosis (CF) patients are characterised by neutrophils that release high amounts of elastase overwhelming the local antiprotease shield. Inhalation of α₁-antitrypsin (AAT) may restore the protease–antiprotease balance and attenuate airway inflammation in CF airways. The aims of the present study were: 1) to assess the best deposition region for inhaled AAT by two different inhalation strategies; and 2) to examine the effect of 4 weeks of AAT inhalation on lung function, protease–antiprotease balance and airway inflammation in CF patients.

In a prospective, randomised study, 52 CF patients received a daily deposition by inhalation of 25 mg AAT for 4 weeks targeting their peripheral or bronchial compartment. The levels of elastase activity, AAT, pro-inflammatory cytokines, neutrophils, immunoglobulin G fragments and the numbers of Pseudomonas aeruginosa were assessed in induced sputum before and after the inhalation period.

Inhalation of AAT increased AAT levels and decreased the levels of elastase activity, neutrophils, pro-inflammatory cytokines and the numbers of P. aeruginosa. However, it had no effect on lung function. No difference was found between the peripheral and bronchial inhalation mode.

In conclusion, although no effect on lung function was observed, the clear reduction of airway inflammation after α₁-antitrypsin treatment may precede pulmonary structural changes. The α₁-antitrypsin deposition region may play a minor role for α₁-antitrypsin inhalation in cystic fibrosis patients.