Detection of granulocyte-macrophage colony-stimulating factor in patients with pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is an idiopathic lung disease in which the alveolar spaces are filled with surfactant. Recently, it has been proposed that PAP is caused by deficiency of granulocyte-macrophage colony-stimulating factor (GM-CSF) because GM-CSF-knockout mice develop the disease. To examine this possibility, we tested the two hypotheses that lung GM-CSF levels are low and that alveolar macrophages (AM) do not respond to GM-CSF in patients with PAP. Data from 10 adult patients with PAP who underwent therapeutic whole-lung lavage were compared with those of 10 healthy volunteers who underwent bronchoalveolar lavage (BAL) by fiberoptic bronchoscopy. Bronchoalveolar lavage fluid (BALF) and plasma were collected and analyzed for total protein and levels of GM-CSF, interleukin-3, and tumor necrosis factor (TNF)-alpha. Isolated AM were cultured with or without lipopolysaccharide (LPS) or GM-CSF, and production of GM-CSF and TNF-alpha was measured after 24 h. GM-CSF in BALF and plasma was higher in PAP than in control subjects (p