Circulating immune complexes in patients with cystic fibrosis in relation to clinical features.

Immune complexes have been previously reported in the serum of patients with cystic fibrosis. This study was undertaken to relate the finding of complexes with the clinical features of the disease. Immune complexes detected by the 125I-C1q binding assay were found in the sera of 17/60 (28%) of patients with cystic fibrosis (CF). There was no association between the finding of raised levels of immune complexes and duration of chest symptoms, duration of daily sputum production, age, sex, weight, atopy, the presence or absence of malabsorption, pneumothorax, diabetes, Aspergillus precipitins or specific bacterial pathogens in the sputum. There was however a correlation between the finding of increasing circulating immune complexes and decrease in the respiratory function; forced expiratory volume in 1 sec (P less than 0.001) and forced vital capacity (P less than 0.005); also with weight (P less than 0.02). It is possible that the finding of immune complexes, at low levels, in cystic fibrosis are the result of tissue damage rather than its cause.