Safety and Tolerability Study of Liquid Alpha1 Proteinase Inhibitor (API) in Subjects With Cystic Fibrosis

Inclusion Criteria: * Have a confirmed diagnosis of CF: one or more clinical findings consistent with CF and at least one of the following: 1. Sweat chloride ≥ 60 mEq/L by quantitative pilocarpine iontophoresis test OR 2. A genotype with two identifiable mutations consistent with CF (∆F508 homozygous or two alleles known to cause a class I, II, or III mutation) * Have an FEV1 ≥30% of predicted normal as defined by age, gender, and height Exclusion Criteria: * Oxygen saturation \<90% * Changed in treatment regimen within 2 weeks prior to screening * Antibiotics regimen change \< 4 weeks before screening * Persistent colonization with Burkholderia cepacia * Serum IgA \< 50% of lower level of normal