[Circulating immune complexes in primo-secondary and serological syphilis (author's transl)].

Some clinical features of syphilis suggest that immune complexes may be a pathogenetic factor in the syphilitic lesions. Recently, circulating immune complexes have been reported in six patients with secondary syphilis by Søling et al. In our study, the presence of circulating immune complexes was investigated in 42 patients with syphilis (primary, secondary, serological) by the method of C1q binding test. Elevated C1q binding activity was demonstrated in two-thirds of the patients with primo-secondary syphilis, with a significant difference between this group and the controls. Only two of the 21 patients with serological syphilis showed elevated C1q binding activity. Circulating immune complexes, often at moderates rates, appear very early and decrease rapidly during treatment. It was not possible to demonstrate a decline in serum complement in association with elevated C1q binding activity. During five Jarisch-Herxheimer reactions, no increase in circulating immune complexes has been noticed compared to pre-treatment values: this suggests that circulating immune complexes have no essential importance in this reaction. The characterization of the components of these circulating immune complexes by the previously described "radioimmunoprecipitation PEG assay" (RIPEGA) will enable us to state their specificity and to conceive their potential responsibility in some lesions of secondary syphilis, such as nephrotic syndrome.