FIG. 1.

Enhanced expression of HIV-1 by OX40 stimulation from HIV-1 chronically infected ACH-2/OX40 cells. (A) Five groups of ACH-2/OX40 cells (cell groups 3, 4, 5, 6, and 10), four groups ACH-2/mock cells (cell groups 2, 7, 8, and 10), and the parental ACH-2 cell line were stimulated by PFA-fixed SV-T2/gp34 cells or PFA-fixed SV-T2/mock cells at a cell ratio of 2:1 with TNF-α (2 ng/ml) or TNF-β (10 ng/ml). After 3 days, HIV-1 production was determined quantitatively by p24 assay using the culture supernatants. (B) PFA-fixed SV-T2/gp34 cells and PFA-fixed SV-T2/mock cells were preincubated with or without anti-gp34 neutralizing MAb (5A8) or control MAb (Cont.) at 5, 1, 0.2, or 0.04 μg/ml for 1 h at 37°C and then were added to ACH-2/OX40 cells. Culture supernatants were harvested 3 days after coculture. (C) Kinetics of HIV-1 expression after stimulation with gp34 in ACH-2/OX40 cells. Supernatants were harvested at each time point, i.e., at 0, 2, 4, 8, 12, 18, 24, 48, 72, 96, and 120 h, and then tested for p24 titers. All results are the means of values obtained in triplicate. A representative result from two independent experiments is shown.