FIG. 7.

Effect of IFN-λ on the expression of IFN-α/β in macrophages. (A) IFN-α/β mRNA expression. Macrophages were cultured in the presence or absence of IFN-λ (100 ng/ml) for 6 h. Total cellular RNA extracted from cell cultures was subjected to real-time PCR for IFN-α, IFN-β, and GAPDH RNA quantification. The data are expressed as IFN-α or IFN-β mRNA levels relative (fold) to the control (without IFN-λ treatment, which is defined as 1). The results shown are means ± SD for triplicate cultures and are representative of three experiments with cells from three different donors (IFN-treated macrophages versus untreated control: *, P < 0.05; **, P < 0.01). (B) Antibody to IFN-α/βR1 blocks IFN-λ-mediated anti-HIV activity in macrophages. Macrophages were incubated with or without goat anti-IFN-α/βR1 (10 μg/ml) for 1 h prior to treatment with IFN-λ. IFN-α (1,000 IU/ml) or IFN-β (1,000 IU/ml) treatment of macrophages was used as controls. Goat IgG was used as a control IgG to determine the specificity of the antibody to anti-IFN-α/βR1. Macrophages treated with IFN-λ (100 ng/ml) for 24 h were infected with the HIV-1 Bal strain. Culture supernatants were collected for HIV-1 RT activity at day 8 postinfection. The data shown are expressed as percent HIV RT activity in IFN-treated cultures compared to control cultures (without IFN treatment, which is defined as 100%). The results shown are means ± SD for triplicate cultures and are representative of experiments using cells from three different donors (**, P < 0.01; *, P < 0.05).