IFN-gamma restores HIV- and non-HIV-specific cell mediated immune response in vitro and its activity is neutralized by antibodies from patients with AIDS.

The addition of IFN-γ to cultures of peripheral blood mononuclear cells (PBMCs) obtained from asymptomatic HIV-infected patients increased cell proliferation in response to HIV envelope synthetic peptides (Env), influenza A virus (VIRUS), andallogeneic lymphocytes (ALLO) but not to phytohaemagglutinin (PHA) stimulation. F(Ab)2 fragments of IgG purified from the sera of HIV-seropositive patients specifically interfered with IFN-γ-induced cell proliferation in response to recallantigens. Neutralization of the lymphokine activity was found to be sustained by specific IFN-γ antibodies. Data obtained demonstrate that IFN-γ can restore the cell-mediated immunity of a number of asymptomatic HIV+ individuals invitro, while IFN-γ antibodies present in sera of patients with AIDS interfere with the activity of the lymphokine.