Complement activation is associated with the presence of specific human immunodeficiency virus (HIV)-anti-HIV immune complexes in patients with acquired immunodeficiency syndrome-related complex or lymphoadenopathy syndrome.

The complement system was examined in a group of eight patients (six with lymphoadenopathy syndrome (LAS); two with acquired immunodeficiency syndrome (AIDS)-related complex (ARC], who were found to be human immunodeficiency virus (HIV)-positive, for the presence of specific HIV-anti-HIV complexes. A significant impairment of the classical and/or alternative pathway was found associated with the presence of cleavage fragments of C3 and/or B and a significant reduction in the complement factors studied. Ultracentrifugation fractions of serum samples obtained from one of the patients were assessed for the detection of specific HIV-anti-HIV (GP41-anti-GP41) complexes and were incubated with normal human serum to determine their complement activation capacity. A clear complement activation was found with the fraction in which a clear peak of HIV-anti-HIV (GP41-anti-GP41) immune complexes was present. The results demonstrate that specific immune complexes and complement activation are sometimes concomitantly present in patients with AIDS-related disease and that specific immune complexes may be one of the causal factors of the pathogenesis of complement activation in these patients. Possible consequences for the severe immune regulation with relevance to the dramatic failure in treating the virus effectively are discussed.