In vivo antitumor activity of EBV-CTL therapy. Patient no. 3 received EBV-CTLs containing greater than 90% of CD3⁺CD4⁺ T cells. Eight weeks after the infusion, for an increase of liver enzymes, a biopsy was performed to exclude the occurrence of graft rejection (A). Immunohistochemistry analysis shows presence of B cells positive for LMP1 (top panels) and massive infiltration of CD4⁺ T cells, surrounding the EBV-positive areas (bottom panels), suggesting the specific homing of CTLs in the tumor area. (B) Biopsy at resolution: no LMP1-positive cells are detectable. Images were acquired with a Zeiss Axioskop microscope (Carl Zeiss, Gottingen, Germany) with a 20×/0.50 NA Neofluor objective lens. Cells were stained with hematoxylin (Mayer)–eosin. Images were photographed with a Spotmatic RT camera and processed with Spotmatic 3.4 PC/3.3.2 (Diagnostic Instruments, Sterling Heights, MI).