Autoantibodies in serum and sputum from patients with cystic fibrosis.

Sera from 89 patients with cystic fibrosis (CF) and 88 control persons 
were examined for the occurrence of rheumatoid factors (RF) of the 
IgG, IgA and IgM classes by an indirect immunofluorescence method and 
by the latex fixation slide test. The prevalence of RF-IgG was 
significantly higher (88%) (p less than 0.0005) among the CF patients 
than among the control persons (7%), while no difference was found 
between the two groups with regard to RF of the IgA 
or IgM classes. Fifty-five of the CF patients had chronic Pseudomonas 
aeruginosa infection in their lungs and two or more precipitins against 
these bacteria in their sera determined by crossed immunoelectrophoresis. These CF 
patients did not differ from the 34 CF patients without chronic 
P. aeruginosa infection, neither with regard to prevalence nor titer of 
RFs, but there was a positive correlation between the number of 
P. aeruginosa precipitins in the 55 chronically infected CF patients and 
their titers of IgG-RF. Nineteen CF patients were examined also for 
RFs, antinuclear antibodies (ANA) and anti-DNA antibodies in their sputum sol 
phase and corresponding sera. RFs were demonstrated in the sputum sol 
phase from 6 of the patients by the latex fixation test, 
whereas their sera were negative in this test, possibly indicating a 
local production of RF. Positive reactions for ANA and anti-DNA antibodies 
were found in 7 and 10 of the sputa respectively, and 
in higher titers than in the corresponding sera, also suggesting a 
local production. Titers of autoantibodies in sputum were low and no 
difference was found between patients with chronic P. aeruginosa infection and 
patients without P. aeruginosa infection. The possible role of autoantibodies in 
the patogenesis of pulmonary tissue damage in CF patients is discussed. 
