Aspects of serum and sputum antibody in chronic airways obstruction.
Immunoglobulin levels and precipitating antibody against a range of microbial antigens were measured in simultaneously collected serum and sputum samples from patients with chronic bronchitis (11), cystic fibrosis (9), bronchiectasis (9), and asthma (4). Sputum was prepared by dialysis and high-speed centrifugation methods. Results showed that it was possible to detect precipitating antibody in the sputum, and the rate was increased when both methods were used. A discrepancy was noted between the detection rate in the sputum and serum. This, combined with the lack of correlation between sputum and serum immunoglobulins, lack of relationship between bronchial inflammation and sputum immunoglobulins, and the lack of IgM in the sputum suggested that the antibody and immunoglobulin were locally produced. Sputum IgA (7S) in patients with chronic bronchitis was significantly lower (P less than 0-05) than that found in patients with cystic fibrosis and bronchiectasis. Significant differences (P less than 0-05) were also noted in serum IgG levels between patients with chronic bronchitis, bronchiectasis, and cystic fibrosis while serum IgM levels in patients with chronic bronchitis were significantly lower (P less than 0-05) when compared to serum levels in patients with cystic fibrosis. The presence of precipitating antibody in the sputum raises the possibility that type III reactions may be important in the pathogenesis of these conditions.