CSF2 and pulmonary alveolar proteinosis: ,9 About 90% of PAP cases are caused by generation of anti-GM-CSF autoantibodies,10 which prevent adequate GM-CSF-mediated surfactant clearance by alveolar macrophages.11, 12, 13, 14 The standard of care is whole-lung lavage,15,16 an invasive technique where the lipoproteinaceous surfactant is washed out of each lung in turn under anesthesia at regular intervals.