Granulocyte-macrophage colony-stimulating factor inhalation therapy for patients with idiopathic pulmonary alveolar proteinosis: a pilot study; and long-term treatment with aerosolized granulocyte-macrophage colony-stimulating factor: a case report.

Idiopathic pulmonary alveolar proteinosis (IPAP) is considered to be caused by an autoantibody to the granulocyte-macrophage colony-stimulating factor (GM-CSF), which neutralizes GM-CSF and therefore impairs the differentiation of alveolar macrophages. The authors have previously characterized the BAL fluid and alveolar macrophages obtained from three IPAP patients who were successfully treated with aerosolized GM-CSF and demonstrated restoration of the cell number, expression of surface marker, and phagocytic ability of the alveolar macrophages as well as a decrease in the autoantibody levels in the BAL fluid. The condition recurred in one of the patients after 20 months. This patient underwent a second and third course of GM-CSF inhalation therapy with the same dose and schedule as the first one. Since the second therapeutic intervention did not succeed in producing any improvement in the symptoms and disease markers, the authors used a new nebulizer and a liquid preparation of the drug instead of the lyophilized preparation for the third therapeutic session and this restored the respiratory function considerably. A 6-month maintenance therapeutic regimen with a lower GM-CSF inhalation frequency brought about a further improvement in the disease markers. The results suggest that the efficacy of GM-CSF inhalation therapy might be related to the drug preparation mode, choice of nebulizer, and duration of treatment.