DCs matured in the presence of Tr1-like cell supernatants induce the proliferation of conventional effector T cells. Peripheral-blood monocytes were cultured for 3 days in media containing GM-CSF and IL-4. These immature DCs were then incubated for 24 hours in control media containing GM-CSF/IL-4 (A), and supernatants from T cells activated with CD3 (B), CD3/CD28 (C), or CD3/CD46 (D), and maturation was induced by LPS addition for 24 hours. The matured DCs were washed and used in an MLR with allogeneic PBMCs. The cytokine profile of the proliferating PBMCs was analyzed after 5 days using the Th1/Th2 cytokine bead array (BD Biosciences). Data shown represent the mean cytokine production ± SD of 3 independent experiments performed in triplicate. The observed level of significance for the differences in the amount of cytokines produced by DCs treated with either control media or different supernatants was P > .15 by the paired Student t test in all cases.