Autoimmune pulmonary alveolar proteinosis may not be invariably lifelong: exponential decay of anti–GM-CSF autoantibodies over more than a decade

Extract Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare disorder caused by neutralizing autoantibodies against granulocyte–macrophage colony-stimulating factor (GM-CSF), resulting in impaired alveolar macrophage function and progressive accumulation of proteins, phospholipids, and cholesterol within the alveolar spaces 1–3. Although advances in whole-lung lavage (WLL) and inhaled GM-CSF therapy have substantially improved clinical conditions 4–6, aPAP has generally been regarded as a chronic autoimmune condition characterized by persistent production of anti–GM-CSF autoantibodies (GMAb). However, the long-term immunological trajectory of circulating GMAb beyond the first decade has not been systematically clarified. Because longitudinal measurement of GMAb is not routinely accessible in most clinical settings and often unavailable outside specialized reference laboratories, the long-term immunological natural history of aPAP has remained essentially unexplored—an important gap in an antibody-mediated autoimmune disease in which autoantibody kinetics are integral to disease activity.