ObjectiveTo describe the clinical,radiographic,and laboratory features of autoimmune pulmonary alveolar proteinosis (PAP) from a single center. MethodsConsecutive autoimmune PAP cases diagnosed in the Nanjing Drum Tower Hospital between January 2006 and December 2012 were recruited in the study. The clinical,radiographic and laboratory data of the PAP patients were analyzed to explore the clinical significance of serum GM-CSF autoantibody (GMAb) and serum cytokeratin (CYFRA21-1). ResultsThe median serum GMAb level of the 26 cases was 28.64 μg/mL (interquartile range,19.2-75.4 μg/mL),which were diagnosed as autoimmune PAP based on the serum GMAb levels of these patients all above the cut-off value of 2.39 μg/mL while the serum GMAb levels of 30 normal controls were 0.10(0.05-0.15)μg/mL and all below the cut-off value. 34.6% of all recruited 26 autoimmune PAP patients had identified occupational inhalational exposure. There was no significant correlation in the serum GMAb in autoimmune PAP patients with disease severity scores (DSS),lung function parameters,chest high resolution computed tomography (HRCT) scores,or PaO2 (P>0.05). There was significant correlation of DSS of autoimmune PAP patients with PaO2,FVC%pred,TLCO%pred,opacity extent score of chest HRCT,and opacity severity score of chest HRCT (P<0.05). The median serum level of CYFRA21-1 of the autoimmune PAP patients was 9.9(4.3-19.5)ng/mL,which was significant higher than that of the normal control group (P<0.05). However there was no significant correlation in the serum CYFRA21-1 in the autoimmune PAP patients with DSS,lung function parameters,and chest HRCT scores. 92.3% of the chest HRCT of 26 autoimmune PAP patients had crazy paving sign,while 100% of them had geographic sparing sign. ConclusionSerum GMAb and CYFRA21-1 may be important biomarkers for diagnosis of autoimmune PAP. The PAP with occupational inhalational exposure constitutes a high proportion of autoimmune PAP patients.