CSF2 and pulmonary alveolar proteinosis: Direct pathologic effect has perhaps been most convincingly shown for the role of ACAAs against GM-CSF in the disease pulmonary alveolar proteinosis, where the cytokine GM-CSF is integrally involved in the disease process, and passive transfer of autoantibodies purified from the serum of patients with the disease reproduces the disease phenotype in non-human primates (54).