Patient disease responses and PR1-CTL immune responses.

*Patient receiving imatinib 400 mg daily.−Denotes that the result that could not be determined due to an insufficient number of cells.NA Not applicable since IFN was not withdrawn in these patients.BCR-ABL transcripts were determined with quantitative real-time PCR (RQ-PCR) of peripheral blood, as expressed on the International Scale (IS). PR1/HLA-A2 tetramers were used to enumerate PR1-CTL in PBMC, and PBMC were left unstimulated or stimulated with either the PR1 peptide or with SEB and analyzed for IFNγ production by flow cytometry. Shown are the frequencies of CD8+ T cells that produce IFNγ, after subtracting percentage of CD8+ cells that stain positive for IFNγ without any stimulation. The highest frequency of CD8+ cells that produce IFNγ when stimulated with PR1 are shown.