Elevation of tumour markers in serum and bronchoalveolar lavage fluid in pulmonary alveolar proteinosis.

It is unclear whether tumour markers are generally increased in the serum and bronchoalveolar lavage fluid (BALF) of patients with pulmonary alveolar proteinosis (PAP). To clarify this point, levels of tumour markers were measured in the serum and BALF of patients with PAP. Squamous cell carcinoma (SCC) antigen, carcinoembryonic antigen (CEA), and carbohydrate antigens sialyl Lewis (CA 19-9) and sialyl SSEA-1 (SLX) were assayed with radioimmunoassay kits. Cytokeratin 19 fragments (CYFRA) were measured by enzyme-linked immunosorbent assay. Values for the tumour markers in serum, except for SCC, exceeded cut-off values in some PAP patients. Levels of the markers were higher in BALF compared with those in serum, and were significantly elevated in PAP patients compared with control subjects. There was a significant inverse correlation between CA19-9 level in BALF and arterial oxygen tension (PaO2) in PAP patients. A gradual elevation of CA19-9 and SLX was observed in a patient who showed a decrease in PaO2 level during the study period. In the light of these findings, it is possible that levels of tumour markers in BALF, especially levels of CA19-9 and SLX, may reflect the severity of the disease in PAP patients.