Opsonization of mucoid and non-mucoid Pseudomonas aeruginosa by serum from patients with cystic fibrosis assessed by a chemiluminescence assay.

Since Pseudomonas aeruginosa (P. aeruginosa) is a major pathogen for patients with cystic fibrosis (CF), we compared serum from CF patients to serum from controls for opsonic activity against a mucoid and a non-mucoid strain of this organism. A chemiluminescence assay was employed to assess opsonic activity using control polymorphonuclear leukocytes and organisms opsonized with: (1) serum from CF patients who were colonized with P. aeruginosa; (2) serum from CF patients who were not colonized with this organism; and (3) pooled control serum. Serum from CF patients who were colonized with P. aeruginosa had 1.5-2-fold greater opsonic activity against mucoid and non-mucoid P. aeruginosa respectively than serum from non-colonized CF patients or pooled control serum. The increased activity was attributed to antibody, since adsorption of serum with the organism removed much of its opsonic activity. Heat inactivation also decreased opsonic activity indicating that complement plays an important role. We speculate that the increased levels of opsonic antibodies in patients colonized with P. aeruginosa may play a role in the pathogenesis of lung damage by triggering neutrophil migration to the lung.