Abstract
Immunosuppressive acidic protein (IAP) and carcinoembryonic antigen (CEA) levels in sputum from patients with various respiratory diseases were measured by single radial immunodiffusion method and enzyme immunoassay, respectively. The sputa were effectively solubilized with 2% N-acetyl-L-cysteine prior to the analysis. The mean value±S.D. of IAP (μg/ml) in sputum from patients with lung cancer (n=23), chronic bronchitis (n=45), bronchial asthma (n=5), bronchiectasis (n=6), pneumonia (n=5), chronic pulmonary emphysema (n=9) and idiopathic pulmonary fibrosis (n=18) was 212±396, 121±131, 110±141, 101±53, 68±55, 62±23 and 60±32, respectively. The IAP level in sputum increased in proportion to purulence and the number of causative bacteria cultured, except for a patient with bronchiolo-alveolar carcinoma. There was a weak correlation between serum levels and sputum levels of IAP (r=0.39, p<0.05). The mean value±S.E. (μg/ml) of CEA in sputum was 2, 387±1, 095 in patients with lung cancer (n=14) and 444±102 in those with non malignant pulmonary diseases (n=30), with a significant difference between them (p<0.05). These results indicate that IAP in sputum reflects local inflammatory change and that measurement of CEA in sputum appears to be a useful simple test in the diagnosis of lung cancer.
