Autoantibodies against GM-CSF have been associated with the development of idiopathic autoimmune pulmonary alveolar proteinosis (PAP), a rare but potentially serious lung disease, in which abnormal accumulation of pulmonary surfactant protein occurs within the alveoli due to insufficient clearance by GM-CSF-starved macrophages [37, 38]. This evidence concerns the gene CSF2 and pulmonary alveolar proteinosis.