Circulating immune complexes in sera of patients infected with Echinococcus granulosus

Circulating immune complexes (CIC) were investigated by the C1q binding assay in sera of 23 patients infected with Echinococcus granulosus. For the 23 sera studied, nine were found to be positive in the test. When the samples were grouped according to the cyst localization, the highest rate of CIC positively was found in the group of sera from patients with pulmonary cyst; in this group, double diffusion (DD) and indirect haemagglutination (IHA) tests gave a low rate of positivity for antibodies directed against parasitic antigens. Rheumatoid factor, anti-nuclear and anti-mitochondrial autoantibodies were not detectable in patients' sera by indirect immunofluorescence technique (IIF). Anti-smooth muscle autoantibodies, detectable by IIF, were present in 56% of the sera and this positivity was higher in the hepatic (83%) than in the pulmonary form (40%).