LPS-desensitized DC are poor inducers of IFN-γ production in the MLR: restoration of the IFN-γ inducing activity by pretreatment of desensitized DC with PGE2 plus TNF-α. DC were cultured in the presence or absence of LPS at the concentrations indicated (primary culture). Day-5 DC were recultured with or without LPS (10 ng/mL) or PGE2 (10 μmol/L) plus TNF-α (1,000 U/mL) for 48 hours and then 1 × 10³ DC were used as stimulators of 2 × 10⁵ allogeneic T cells. On day 5 of coculture supernatants were obtained and analyzed for IFN-γ levels using a specific ELISA. Data represent mean values of triplicate measurements with SD from one experiment representative of two independent experiments.