Phase II Study of the Safety and Efficacy of Inhaled Alpha-1 Antitrypsin (AAT ) in Cystic Fibrosis Patients

Inclusion Criteria: * Diagnosis of CF by clinical symptoms and positive sweat test or disease inducing mutation. * Age \>5 yrs * Proven ability to perform reproducible PFTs * FEV1 \>25% predicted * Steady disease state for 3 months and no decrease in lung function exceeding 10% during that period * Colonization * Stable concomitant therapy \>2 weeks prior to visit 1 and during the study * Non-tobacco user of any kind * Ability for sputum induction * Written informed consent Exclusion Criteria: * Severe CF with an FEV1 of \<25% predicted * History of lung transplant * Active allergic bronchopulmonary aspergillosis (ABPA) * Treatment with additional antibiotics (beyond standard CF treatment) for a period of 14 days before study entry (routine antibiotics permitted) * Treatment with additional oral and/or IV steroids (beyond standard CF treatment) for a period of 14 days before study entry (screening day) * Known hypersensitivity to plasma products * IgA deficiency * Uncontrolled hypertension * Lung surgery in the previous two years * Being on any thoracic surgery waiting list * Severe concomitant disease * Hospitalization within 1 month before study entry, not due to an airway disease * Severe liver cirrhosis with ascites * Hypersplenism * Grade III/IV oesophageal varices * Active pulmonary exacerbation within the 4 weeks prior to screening * History of significant hemoptysis within the previous year * Use of tobacco products or recreational drugs * Pregnancy or breastfeeding * Any serious or active medical or psychiatric illness which, in the opinion of the investigator, would interfere with patient treatment, assessment, or compliance with the protocol. * Being a female of child-bearing age without adequate contraception * Participation in research study within 1 month