High levels of complement-activation capacity in sera from patients with cystic fibrosis correlate with high levels of IgG3 antibodies to Pseudomonas aeruginosa antigens and poor lung function.
Heat-stable opsonins from sera of cystic fibrosis (CF) patients were investigated for their ability to activate complement. Complement activation by Pseudomonas aeruginosa after opsonization with patient serum was examined in a complement-consumption assay. Absorption of patients' sera with formalin-treated and boiled bacteria removed specific antibodies and the complement activation decreased. We found a positive correlation between serum complement-activation ability and IgG3 antibody levels to lipopolysaccharide (LPS), alginate, and a crude mixture of P. aeruginosa antigens (sonicate) in a group of patients with high levels of anti-Pseudomonas precipitins. In the same group of patients a significant negative correlation was found between complement activation and lung function. Eighteen patients have been followed longitudinally with serum samples covering the pre-infection, the early, and the late stages of chronic infection. Patients with poor lung function showed significantly higher levels of complement-activation capacity. We conclude that patients with high levels of specific IgG3 antibodies are able to induce a high level of complement activation and then develop more aggressive pulmonary tissue damage, probably secondary to local immune complex formation.
Pressler
T
T
Danish CF Center, Department of Paediatrics, Rigshospitalet, Copenhagen, Denmark.
Jensen
E T
ET
Espersen
F
F
Pedersen
S S
SS
Høiby
N
N
D000293:Adolescent; D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology*; D003167:Complement Activation / Q000276:immunology*; D003165:Complement System Proteins / Q000378:metabolism*; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008137:Longitudinal Studies; D011550:Pseudomonas aeruginosa / Q000276:immunology*
D000942:Antigens, Bacterial; D007074:Immunoglobulin G; D003165:Complement System Proteins