Transduced and mock-transduced progeny of cord blood and bone marrow CD34⁺ cells show similarly potent stimulatory function as accessory cells for resting T-cell responses. CD34⁺ cells were cultured in IMDM-20% FCS with c-kit-ligand, GM-CSF, and TNFα. Proliferating cells were transduced on day 3 of culture by cocultivation for 24 hours and were recultured in fresh medium with replenished cytokines for an additional 8 to 10 days. Nonadherent cells were stained with FITC-anti-mCD2 and candidate dendritic cells were cytofluorographically sorted according to the presence or absence of surface mCD2. Sorted cells were used in graded doses as stimulators in the allogeneic (A and B) mixed leukocyte reaction (MLR) or as stimulators of autologous T cells after pulsing with SEA superantigen or tetanus toxoid antigen (B). Cord blood progeny are evaluated in (A) and bone marrow progeny are evaluated in (B). The amount of ³HTdR incorporated by the responder T cells was plotted against the dose of stimulator cells as a measure of stimulatory capacity.