Reactive antibodies in the bronchial washings of lung cancer patients.

Lung-carcinoma-reactive antibodies have been previously isolated from tumor tissues and pleural effusions. To explore the immunoglobulin (Ig) content of bronchial secretions, bronchial washings of patients with inflammatory and neoplastic lung diseases were studied with respect to Ig levels and specificity. Expressed as Ig/potassium ratios, statistically significant increases in Ig levels were found in inflammatory diseases and even higher increases in lung carcinomas. The isolation of Ig from bronchial washings was achieved by dissociation of immune complexes at low pH, neutralization and subsequent purification by anion exchange chromatography. The isolated immunoglobulins were tested in indirect immunofluorescence against lung cancer cells of various histologic types in tissue cultures and fresh suspensions. Positive cytoplasmic fluorescence was obtained with cells of adeno carcinomas and squamous-cell carcinomas of the lung but not with cells of normal lung. The accessibility of bronchial washings makes the investigation of their lung-cancer-reactive immunoglobulins relatively easy and raises the possibility of its eventual conversion into a screening test.