The investigators designed an experimental, randomized by parallel groups, stratified according to previous treatment, open-label study evaluating the superiority of the combination of whole lung lavage/inhaled GM-CSF versus whole lung lavage alone in patients with pulmonary alveolar proteinosis. The primary efficacy objective is the total resolution of the pulmonary involvement. PAP patients matching the enrolment criteria will enter the study. If requiring the first WLL, they will be randomized to receive WLL (1st level control group) or WLL/followed by inhaled GM-CSF, according to an acute (12 weeks) followed by maintenance (6 months) schedule (1st level treated group).