[Incidence and specificity of circulating immune complexes in infectious mononucleosis (proceedings)].

Occurrence of immune complexes in infectious mononucleosis has been investigated by the 125I Clq binding assay. Increased serum Clq-binding activity was found in 87% of the 23 patients studied during the acute stage of the disease. The serum Clq-binding material detected has properties identical to those of immune complexes. IgG antibodies dissociated from the complexes at acid pH and F (ab)'2 fragments obtained after treatment by pepsin appeared to be directed against the viral capsid antigen of Epstein-Barr virus.