Immune complexes in the sputum of patients with cystic fibrosis suffering from chronic Pseudomonas aeruginosa lung infection.

12 cystic fibrosis (CF) patients chronically infected with mucoid P. aeruginosa and 
presenting multiple precipitins in serum against this bacterium and 12 patients 
without P. aeruginosa infection were examined for occurrence of soluble immune 
complexes in their sputum sol phase by a complement consumption assay 
and a solid phase rheumatoid factor binding assay. The correlation between 
the results obtained in the two assays was significant (r = 
0.625, p less than 0.01). The patients chronically infected with P. 
aeruginosa showed a significantly (p less than 0.01) higher frequency of 
immune complex activity in their sputum sol phase, as compared to 
the patients without P. aeruginosa lung infection. These findings point to 
the possibility that chronic lung infection with mucoid P. aeruginosa in 
CF may be an immune complex disease. 