ANTIBODIES AGAINST CHROMOSOMAL BETA-LACTAMASE

A murine monoclonal anti-chromosomal beta-lactamase antibody was devel oped and an immunoblotting technique was used to study the presence of serum and sputum antibodies against Pseudomonas aeruginosa chromosoma l group 1 beta-lactamase in patients with cystic fibrosis (CF). The se rum antibody response was studied with serum samples collected in 1992 from 56 CF patients in a cross-sectional study and with serum samples from 18 CF patients in a longitudinal study. Anti-beta-lactamase immu noglobulin G antibodies were present in all of the serum samples from the patients with chronic bronchopulnonary P. aeruginosa infection (CF +P) but in none of the CF patients with no or intermittent P. aerugino sa infection. Anti-beta-lactamase antibodies were present in serum fro m CF+P patients after six antipseudomonal courses (median) and correla ted with infection with a beta-lactam-resistant strain of P. aeruginos a. The sputum antibody response and the beta-lactamase activity in spu tum samples from 14 of the CF+P patients were also studied. beta-Lacta mase antibodies were present in 10 of these samples. P. aeruginosa str ains isolated from these samples were partially derepressed, producing group 1 cephalosporinase. We found a wide range of chromosomal beta-l actamase activity in the sputum samples, with no correlation with basa l or induced activity of beta-lactamase expression. The presence of an ti-beta-lactamase antibodies in endobronchial sputum could be an impor tant factor in the defense against the infection. On the other hand, i mmune complexes between beta-lactamase and corresponding antibodies co uld play a role in the pathogenesis of bronchopulmonary injury in CF b y mediating hyperimmune reactions.