QUANTITATIVE STUDIES ON IMMUNOLOGICALLY SPECIFIC AND NON‐SPECIFIC ABSORPTION OF PSEUDOMONAS AERUGINOSA ANTIBODIES IN SERUM FROM CYSTIC FIBROSIS PATIENTS

Abstract

A quantitative determination of anti-Pseudomonas immunoglobulins was carried out by means of rocket-line Immunoelectrophoresis in the serum from 19 cystic fibrosis (CF) patients with chronic P. aeruginosa infection and with many precipitins against these bacteria (CF + P), from six CF patients without P. aeruginosa infection (CF-P) and from nine normal persons. On an average P. aeruginosa antigens could absorb 7.7% of IgG, 8.49% of IgA and 29% of IgM from CF + P sera, whereas no detectable IgG and IgA and only 14.6% IgM were absorbed from normal sera and only 1.2% of IgG, 3.8% of IgA, but 29% of IgM was absorbed from CF-P sera. The results show that most, if not all, of the P. aeruginosa precipitins belong to the IgG and IgA classes, but that these precipitins can account only for a part of the increased levels of immunoglobulins in CF + P patients. Staphylococcus aureus containing protein A (strain Cowan I) could absorb 95% of the precipitating antibodies against P. aeruginosa and 92% of IgG, 27% of IgA and 34% of IgM in CF + P patients. The absorption of P. aeruginosa precipitins by protein A points to a possible synergism between S. aureus and P. aeruginosa infections in the lungs of CF patients, since S. aureus may interfere with antibody-mediated immune elimination of P. aeruginosa. Such a mechanism may also facilitate infections with other microorganisms in these patients.