Antibody-dependent cell-mediated cytotoxicity can protect PBMC from infection by cell-associated HIV-1

We have developed a novel in vitro assay system to study the role of antibo dy-dependent cell-mediated cytotoxicity (ADCC) in protection against HIV-1 infection by cell-associated virus. HIV-1-infected NK-resistant cells are m ixed with specific antibody and unstimulated PBMC and ADCC is allowed to oc cur over several hours. The PBMC are then activated and cultured to allow v irus replication in newly infected T cells. To ensure that ADCC is the only mechanism by which protection could occur we have used haptenated (TNP) in fected cells and anti-hapten antibody. Anti-hapten sera completely protecte d PBMC from infection by haptenated HIV-infected cells in ADCC protection a ssays. F(ab'), fragments of anti-hapten IgG showed no protection, confirmin g that ADCC was responsible for protection by anti-hapten IgG. PCR analysis for HIV-1 DNA confirmed the elimination of infected cells. We believe this to be the first direct demonstration that ADCC alone can protect PBMC from infection by cell-associated HIV-1. (C) 1999 Academic Press.