Direct Detection of Infectious Human Immunodeficiency Virus Type 1 (HIV-l) Immune Complexes in the Sera of HIV-1-Infected Persons

The sera of human immunodeficiency virus type 1 (HIV-1 )-infected subjects were examined for the presence of infectious HIV-I-antibody complexes by their ability to infect Fcγ receptor (FcγR)-bearing cells. Infection of FcγR-bearing cells by a serum in which halfof the p24 antigen was present in a form of immune complexes was inhibited by aggregated human immunoglobulin. Then in studies on 22 sera, 9 sera produced p24 antigen during 14 days of culture in U937 cells. HIV-1 p24 production was inhibited or delayed by the pretreatment ofcells with aggregated human immunoglobulin in 6 of the 9 sera that were infectious. These results may reflect interactions between virus-antibody complexes and FcγR-bearing cells in vivo because serum itself was used as the source of virus and virus-antibody complexes. The results indicate that infectious HIV-1 immune complexes are present in the circulation of HIV-I-infected patients.