Isolation and characterization of circulating immune complexes in cystic fibrosis.

A methodology for the isolation and immunologic characterization of IgG-containing circulating immune complexes (IgG-CIC) as detected by the 125IClq-binding assay (ClqBA) is described. We applied this methodology to sera from patients with cystic fibrosis (CF), both positive and negative for IgG-CIC. We used latex-fixation-positive rheumatoid arthritis sera and normal human sera as positive and negative controls, respectively. All IgG-CIC-positive serum samples from CF patients were found to contain antibodies against Pseudomonas aeruginosa in the isolated complexes. Some patients also had antibodies in CIC specific for Staphylococcus aureus and Candida albicans. CIC specificity corresponded to respiratory tract colonization for each patient.