The initial activation stimulus commits MoDCs irreversibly to expressa specific functional phenotype. Migration of MoDCs initially stimulated with either GM-CSF plus TNF-α plus IFN-α plus PGE₂ or with CD40L₁ plus IFN-γ or with CD40L₃ plus IFN-γ. MoDCs were washed twice 24 hours after stimulation. The indicated activation stimuli (no cytokines or GM-CSF plus TNF-α plus IFN-α plus PGE₂) were added either (A) immediately or (B) following a 24-hour rest period in medium without cytokines (mean ± SEM of 4 experiments are shown, *P < .05 as compared with no cytokine condition).