Evidence for a Defect of Antibody-dependent Cellular Cytotoxic (ADCC) Effector Function and Anti-HIV Gp120/41-specific ADCC-mediating Antibody Titres in HIV-infected Individuals

Antibody-dependent cellular cytotoxicity (ADCC) is an important antiviral effector mechanism. However, its role, as well as the functional integrity of the ADCC-effector cells in HIV infections, is not well understood. For studying gp120/41-specific ADCC, we recently developed a virus-free target cell system, using a natural killer (NK) cell activity-resistant human lymphoid cell line of B lineage, which was transfected with the env gene of the human immunodeficiency virus type 1 (HIV-1); gp120/41-expressing cell clones were thus selected. In this study, these gp120/41-expressing cloned cells were used as targets in a gp120/41-specific ADCC assay for (a) examining the functional integrity of ADCC-effector cells from HIV-seropositive individuals, and (b) titrating the sera of these individuals for gp120/41-specific, ADCC-mediating antibodies. Our data indicate for the first time that the percentage of sera positive for ADCC-mediating antibodies to gp120/41 is higher in individuals with CD4 counts < or = 400 and > or = 200/mm3. The individuals with CD4 counts < 200/mm3 were found to have the lowest titers of these antibodies in their sera. The ADCC-effector function of the peripheral blood mononuclear cells (PBMC) of HIV-infected individuals was significantly (p < 0.05) reduced as compared to the PBMC from healthy, HIV-seronegative individuals. Further, human recombinant IL2 and interferon-gamma were found to exert a significant (p < 0.05) enhancing effect on ADCC mediated by PBMC from these HIV-infected individuals.(ABSTRACT TRUNCATED AT 250 WORDS)