Dehydroepiandrosterone sulfate and progesterone exhibited an immunomodulatory effect on the tolerogenic characteristics of IFN-α-induced dendritic cells. The hormone effects depended on the initial level of allostimulatory activity of dendritic cells in mixed lymphocyte culture. However, dehydroepiandrosterone sulfate significantly more often stimulated allostimulatory activity by attenuating the tolerogenic properties of dendritic cells, while progesterone potentiated their tolerogenic potential. The capacity of the hormones (dehydroepiandrosterone sulfate and progesterone) to attenuate tolerogenic activity of dendritic cells was associated with reduction of FasL expression on these cells, while the increase in tolerogenic activity was associated with the increase in the percentage of CD123(+) dendritic cells, and under conditions of modification with dehydroepiandrosterone sulfate it was associated with increased B7-H1 expression. Possible contribution of indolamine-2,3-dioxygenase and prostaglandin E2 to stimulation of tolerogenic characteristics of dendritic cells modified with dehydroepiandrosterone sulfate and progesterone, respectively, was demonstrated.