Characteristics of patient CTL lines. The growth kinetics, immunophenotype, and cytolytic properties of the CTL lines generated from our cohort of SOT recipients are shown. EBV-CTL lines were expanded from PBMCs of 35 SOT patients by weekly stimulations with irradiated LCLs and biweekly feeding with IL-2. (A) The mean ± SD of the growth rate of all 35 CTL lines generated. (B) The majority of the CTL lines were CD3⁺CD8⁺ and TCRαβ-positive T cells. Data are shown as the mean % of positive cells ± SD. (C) The cytotoxic activity of these expanded lines. Lysis of autologous LCLs (•) is significantly higher compared with lysis of HLA-mismatched LCLs (▴). Autoreactivity was excluded by absence of lysis of autologous PHA blasts (▪). Shown is the mean Cr⁵¹ release of the CTL lines ± SD. (D) Killing of autologous LCLs (▦) is inhibited after preincubation with anti–class I (▪) and anti–class II (▥) blocking antibodies of CTLs prevalently composed of CD8⁺ T cells (left bars) and of CTLs prevalently composed of CD4⁺ T cells (right bars). □ shows lysis in the presence of isotype control mAbs. Bars indicate mean Cr⁵¹ release of CTLs ± SD.