Alloreactivity of virus-specific T-cell lines. Eleven virus-specific T-cell lines, of which 7 are shown in this figure, were stimulated with a panel of EBV-LCLs for 18 hours and IFNγ production was measured by ELISA. In experiments in which EBV-specific T-cell lines were tested, we excluded the EBV-LCLs expressing the HLA molecules to which the T-cell lines were restricted. The purity of the virus-specific lines was analyzed by tetramers and CD8 staining, and all T-cell lines proved to be more than 98% pure. As a positive control, the lines were tested against EBV-LCLs expressing the HLA-restricting molecule of the viral epitope, loaded with the viral peptide recognized by the T-cell lines (pept). (A) The CMV-pp50/HLA-A1–specific lines of patient MBX recognized almost all EBV-LCLs. (B) The CMV-pp50/HLA-A1–specific line of patient UKL showed broad alloreactivity. (C) Two of the 10 tested T-cell lines exerted no alloreactivity against the tested EBV-LCLs of which 1, the pp50/HLA-A1–specific line, is shown. (D) The CMV-IE1/HLA-B8 recognized a limited number of EBV-LCLs. (E) The BMLF1/HLA-A2–specific line showed high reactivity against all HLA-A11–positive EBV-LCLs and 1 HLA-A11–negative EBV-LCL. (F) The VZV-IE62/HLA-A2–specific line of patient PKO recognized a limited number of EBV-LCLs. (G) EBNA3A/HLA-B8–specific line recognized EBV-LCLs expressing either HLA-B44 or HLA-B55. Experiments were performed in duplicate, mean values are shown ± SD.