CTL clone RDR173 lyses tumor cells and hematopoietic cells. Lysis of patient-derived tumor cells (A), EBV-LCL cells (B), and donor-derived EBV-LCL cells (C) was tested in a CFSE-based cytotoxicity assay. Target cells were labeled with CFSE and incubated for 48 hours with CTL clone RDR173 (E/T ratio, 3:1). As a positive control, target cells were incubated with an HLA-A2–specific alloreactive CTL clone (pos CTL), and as negative control cells were incubated with a male-specific CTL clone (neg CTL).