Specific Aim: To determine whether neutrophils, active elastase, and cytokines measured in sputum induced using hypertonic saline are useful screening tests for determining if a particular agent with known anti-inflammatory properties is a suitable candidate for more extensive clinical trials in patients with CF. This aim will be addressed using an anti-inflammatory agent, ibuprofen, that has been shown to have clinical benefit in CF. A "no treatment" arm will be included as the control group.