Induction of complete clinical response and T-cell accumulation at tumor site after CTL infusion. A PET scan demonstrating abnormal FDG uptake in the nasopharyngeal region was observed before CTL infusion in another patient (pt 4) with NK/T-cell lymphoma. The follow-up scan 8 weeks after CTL infusion was reported as normal (A). EBV DNA levels in this patient's (pt 4) PBMCs measured by quantitative real-time PCR before and after CTL infusion were plotted against the EBV(LCL)-specific T-cell response after infusion as measured by IFN-γ secretion in ELISPOT assay (B). Using immunohistochemistry, CD4⁺ infiltrating T cells were seen in a lymph node biopsy after CTL infusion, and corresponded to a clearance of LMP2-positive tumor cells in patient 4 (C). Images were acquired with an Olympus BX41 microscope, with a Plan Achromat 40×/0.65 NA oil objective lens (Olympus). Cells were stained with hematoxylin (Mayer)-eosin and CD4 monoclonal antibody (Dako) and LMP2 antibody (gift of Dr Friedrich A. Grässer) were used in immunoperoxidase protocol. Images were photographed and processed as in Figure 3B. Original magnification, ×40.