Murine studies of adoptive transfer have demonstrated that high avidity CTL possess superior in vivo anti-viral and anti-tumor efficacy when compared to low avidity CTL [14,15](In the pmel murine model of melanoma, adoptive transfer of CTL with terminal effector function and phenotype induced by repetitive in vitro antigen and IL-2 stimulation was associated with impaired in vivo anti-tumor efficacy [16]. Here, IL2 is linked to neoplasm.