CSF2 and autoimmune pulmonary alveolar proteinosis: Autoimmune pulmonary alveolar proteinosis (PAP) (aPAP) is characterized by the accumulation of phospholipids and surfactant proteins in the peripheral air spaces due to alveolar macrophage dysfunction caused by anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies (GMAb) [1,2].