NK cell-based cancer immunotherapy.

The identification of spontaneous antitumor immune responses in cancer patients and the demonstration that an intact immune system can prevent against certain forms of malignancies invigorated research efforts in the development of cancer immunotherapies. To date, numerous and diversified approaches are being investigated, thereby providing new means by which to mobilize the cellular and molecular elements of the immune system in order to destroy established cancers. While it is appreciated that tumor-specific cytotoxic T lymphocytes play a critical role in successful immunotherapy, it is becoming increasingly apparent that cellular components of both the innate and the adaptive arms of the immune system can control tumor growth. In particular, natural killer (NK) cells are emerging as key players in the cross-talk between innate and adaptive immunity. With the uncovering of the regulatory mechanisms governing NK cell biology, new immunotherapies based on the harnessing of NK cell antitumor activity are now being developed. In this review, we summarize the role of NK cells in the control of tumor growth and discuss potential cancer therapies incorporating NK cell-mediated antitumor activity.