Serum and effector-cell antibody-dependent cellular cytotoxicity (ADCC) activity remains high during human immunodeficiency virus (HIV) disease progression

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Abstract
The activity of both serum and effector cell antibody-dependent cellular cytotoxicity (ADCC) against human immunodeficiency virus (HIV-1, HIV) was assessed in HIV-infected individuals. The goal was to relate ADCC levels with the stage or progression of HIV disease. Serial serum samples, usually collected at 6-month intervals, from individuals at defined stages of HIV disease (sero-conversion, the HIV-seropositive period before AIDS, and around the time of clinical AIDS diagnosis) were tested. HIV-coated CEM tumor cells were used as targets. Effector-cell ADCC activity was evaluated using fresh peripheral blood mononuclear cells (PBMC) from HIV-infected individuals at different stages of HIV disease. Samples were obtained from male homosexual participants in the Multicenter AIDS Cohort Study (MACS). In seroconverters, ADCC-inducing HIV-specific antibodies were detected at the time that the ELISA antibody test was first positive. Within several months, serum ADCC activity stabilized in each individual. In 29 HIV-seroprevalent individuals (HIV seropositive on their first visit), serum ADCC activity remained constant regardless of whether the individual's HIV disease was stable (high stable CD4;n=9) or rapidly deteriorating (sharply declining CD4,n=10; AIDS progressors,n=10). With respect to effector-cell activity, PBMC from HIV-infected individuals with or without AIDS were capable of mediating ADCC with heterologous and usually with autologous sera. Although the level of NK cytotoxic activity and the level of antibody-armed effector cell activity have been reported to decline as disease progresses, our results support previous observations that ADCC effector-cell activity against antibody-coated targets does not decline in HIV infection. These results indicate that both serum and effector cells with ADCC activity are present in HIV-infected individuals shortly after seroconversion and are maintained throughout HIV disease. Although levels of serum and effector-cell ADCC activity do not predict whether an individual will develop AIDS, CD4 cells which express HIV antigens (either produced endogenously or adsorbed onto the surface) could serve as targets for anti-HIV-mediated ADCCin vivo. ADCC could, thereby, contribute to CD4 T-cell depletion in infected individuals. However, since serum and effector-cell ADCC levels do not seem to relate to disease stage or progression, the protective or pathogenic role that ADCC plays in HIV-disease remains unresolved.