Effects of IL-16/TPO combination on the generation of tolerogenic DCs. The allostimulatory activity of DCs was tested in primary cultures, using monocyte-depleted PBMCs. (A-B) Effects of the presence of IL-16 and TPO at different times of culture. The concomitant presence of IL-16 and TPO during the first 7 days of culture was required to induce the differentiation of tolerogenic DCs. The mean ± SEM from 3 independent experiments is shown. (C) Effects of IL-16/TPO combination on sorted cell subpopulations. The presence of IL-16 plus TPO induced the generation of tolerogenic DCs, which were unable to stimulate the proliferation of allogeneic T lymphocytes, from both CD34⁺/CD4⁺ (top row) and CD34⁺/CD4^- (bottom row) cells. Proliferating lymphocytes identified as CD4⁺/BrdU⁺ double-positive cells. One representative of 4 independent experiments is shown.