Interferon-γ release of CD8⁺ T lymphocytes in response to EYFP antigen. After a 7- to 15-day in vitro stimulation with irradiated, autologous EYFP-positive CD34-enriched bone marrow cells, FSC/SSC gated, CD8⁺ events were analyzed by flow cytometry for their expression of interferon-γ (IFN-γ) after exposure to mock-transduced or EYFP-transduced autologous targets with the percent of CD8⁺ cells positive for IFN-γ indicated in the upper right of the plots. Exposure to PMA/ionomycin was used as a positive control for IFN-γ production. (A) M99149 PBMCs exposed to EYFP⁺ antigen presenting cells (APCs), (B) M99149 PBMCs exposed to mock-transduced APCs, (C) M99149 PBMCs treated with PMA/ionomycin, (D) M00067 PBMCs exposed to EYFP-positive APCs, (E) M00067 PBMCs exposed to mock-transduced APCs, (F) tolerant control animal M99267 PBMCs exposed to EYFP-positive APCs.