Croxatto et al. [107] continued Vacca’s research to prove that PE-NK cells that have been activated by IL-15 in vitro can control tumour growth in vivo; IL-15 not only overcomes the inhibitory effect of soluble factors in MPE, but also restores the effector function of PE-NK cells that have been damaged by exposure to autologous MPE. Here, IL15 is linked to neoplasm.