PRF1 and neoplasm: CD8+ NKT cells from healthy EBV+ humans, EBV-challenged hu-thy/liv-SCID chimeras, or EBV-exposed RTOCs and FTOCs produced much higher amount of perforin (Figure 7B) than that in counterpart CD4+ NKT cells (Figure 7A), indicating that high production of perforin in EBV-induced CD8+ NKT cells was an additional reason for their high cytotoxicity to EBV-associated tumor cells, besides their biased IFN-γ-production [42].