HDACis upregulate the expression of OX40L in HL. (A) Baseline expression of OX40L in lymphoid cell lines by western blot analysis. (B) OX40L expression in HL and MCL cells. Cells were incubated with DMSO, MGCD0103, vorinostat, and SNDX-275 (1 μM) for 24 hours before OX40L levels were analyzed by FACS. MGCD0103 and SNDX-275 increased OX40L expression in HL cells but not in MCL cells. (C) CD40 expression in HL cells. (D) OX40L expression in HL cells. Cells were incubated with DMSO, MGCD0103, and vorinostat (0.1-2.0 μM) for 48 hours and collected, and their OX40L expression was analyzed by FACS. MGCD0103 increased OX40L expression in a dose-dependent manner. Each value is the mean of 3 independent experiments (±SEM). *P < .05, **P < .005. (E) Effect of HDACis on OX40L mRNA levels in HL cells. Results of qRT-PCR after 48 hours of incubation in the absence or presence of MGCD0103 (0.5-1.0 μM) or SNDX-275 (0.5-1.0 μM). Data are presented as mRNArelative units (RU) ± SEM; n = 3 for each condition and kinetic point. *P < .05, **P < .005. (F) Effect of MGCD0103 on OX40L expression. HL cells were incubated with MGCD0103 (0.1-2.0 μM) for 48 hours. Western blot analysis was performed on whole-cell lysates. The effect was more evident with higher doses of MGCD0103 in all HL cell lines.