Detection by enzyme-linked immunosorbent assays of antibody specific for Pseudomonas proteases and exotoxin A in sera from cystic fibrosis patients

Abstract

Enzyme-linked immunosorbent assays were developed to measure serum antibody specific for Pseudomonas elastase, alkaline protease and exotoxin A. Antibody responses to each Pseudomonas antigen were measured in cystic fibrosis (CF) patients who were not colonized with P. aeruginosa, in those who were colonized, in those who were chronically infected with this organism and in control subjects. Antibody levels for each antigen in the colonized and infected CF patients were higher than levels in uncolonized CF patients or non CF control subjects. The antibody responses to elastase were similar in patients of the colonized and infected groups. Infected CF patients had significantly elevated levels of antibody to exotoxin A (P < 0.01) and alkaline protease (P < 0.05) when compared with patients simply colonized with P. aeruginosa. These findings confirm that Pseudomonas alkaline protease, elastase and exotoxin A are produced by Pseudomonas strains which colonize and infect CF patients. As an adjunct to established procedure (X-ray, microbiological culture, etc.), the antitoxin and anti-protease enzyme-linked immunosorbent assays may be clinically useful tests for differentiating colonized CF pateints from those who have more severe Pseudomonas pulmonary infections.