Nfkb1^–/–C-Rel^–/– pDCs fail to stimulate naive T cells in a mixed lymphocyte reaction. pDCs isolated from wt or Rel/NF-κB mutant mice were incubated with CBA/CaH CD4⁺ T cells and incubated for 4.5 days in the absence (–) or presence (+) of CpG1668-ODN. Cultures were then pulsed for 8 hours with ³H-thymidine, harvested, and incorporated radioactivity measured by scintillation counting. The data are representative of 2 independent experiments, and error bars represent variation among triplicate samples within an experiment.