Longitudinal study of immune response to Pseudomonas aeruginosa antigens in cystic fibrosis.

During a 10-year period, the clinical states of 10 cystic fibrosis patients were evaluated on the basis of monthly measurement of lung function and weight; serum antibody titers to alkaline protease and elastase and the number of precipitins to Pseudomonas aeruginosa standard antigen were determined by radioimmunoassay and crossed immunoelectrophoresis. Alkaline protease and elastase concentrations of the P. aeruginosa strains from the patients were measured in vitro. The immune response increased in nearly all patients after the onset of chronic P. aeruginosa lung infection over years, suggesting unimpaired production of these antigens during P. aeruginosa lung infection, whereas the clinical states declined. The mean time for immune response was 15 months for alkaline protease, 11 months for elastase, and 6 months for standard antigen.