Study to assess safety and tolerability of a single dose of study-drug administered to Cystic Fibrosis (CF) patients.

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