Inhaled Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) in Hereditary Pulmonary Alveolar Proteinosis (PAP)

Participants will receive inhaled rhGM-CSF (Sargramostim, Leukine) at the dose of 250 mcg one time per week for 12 weeks. Following an interim safety evaluation, participants may be entered into a second 12 week treatment period where participants will receive either 250 mcg or 500 mcg once weekly. At the end of any treatment period, participants will be followed for 12 additional weeks in the absence of inhaled rhGM-CSF to evaluate safety and efficacy.