Imatinib inhibits virus-specific T-cell proliferation in response to cognate antigen. (A) T cells from healthy HLAA2⁺ human blood donors with tetramer-defined CD8⁺ T-cell responses to CMV pp65_495-503 were purified, CFSE-labeled, and kept in culture for 8 days in the presence of CMV peptide and antibodies against the costimulatory molecules CD28 and CD49d without imatinib (dashed line) or with imatinib at 5 μM (dotted line) or 10 μM (solid line). Data presented are overlaid histograms representing percentage fluorescence intensity of CFSE-labeled HLA A2–CMV pp65_495-503 tetramer-positive CD8⁺ T cells (donors 1-3 [d1-3]) and CMV tetramer-positive CD3⁺ T cells (donor 4 [d]). The y-axis is scaled to 100% defined by the highest value on the y-axis for each condition. (B) Effects of imatinib on expansion of CMV-specific CD8⁺ T cells over a 4-day period in response to cognate peptide. (C) Effects of imatinib on expansion of EBV-specific CD8⁺ T cells over a 4-day period in response to cognate peptide.