Induction of interferon and other cytokines by imiquimod and its hydroxylated metabolite R-842 in human blood cells in vitro

The low-molecular-weight immunomodulator drug candidate, imiquimod (R-837), and its hydroxylated metabolite R-842, induce interferon-alpha (IFN-alpha) in human blood cells in vitro when tested in concentrations of 0.5 microgram/ml or more. The amounts of IFN-alpha found increased with time from 2-6 h of incubation up to 24-48 h, and were dependent on cell number and drug concentration. These two chemicals yielded more IFN-alpha in human peripheral blood mononuclear cell (PBMC) cultures than Other known inducers tested in parallel. They also induced detectable amounts of interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor-alpha in human PBMC cultures in vitro.