Only mature monocyte-derived DCs can initiate a CD4⁺ T-cell response to a neoAg in a primary proliferation assay.

Immature DCs (top) or mature DCs (bottom) were pulsed on day 3 of culture with TT as a recall Ag or KLH as a neoAg, and were plated at day 8 with autologous CD4⁺ T cells at various T/APC ratios. T-cell Ag-specific proliferation was measured by [³H]-thymidine incorporation at day 6 after coculture initiation for TT, or at day 7 for KLH. Unpulsed DCs were used as negative controls for the 6- and 7-day assays, and these controls are shown separately. Each point was done in triplicate. These results are representative of 3 experiments with 3 different donors.