**Clinical Applications of Natural Killer Cells**

**Clinical Applications of Natural Killer Cells**

DOI: 10.5772/intechopen.68991

Yui Harada, Koji Teraishi, Minori Ishii, Hiroshi Ban and Yoshikazu Yonemitsu Hiroshi Ban and Yoshikazu Yonemitsu Additional information is available at the end of the chapter

Yui Harada, Koji Teraishi, Minori Ishii,

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.68991

#### **Abstract**

Natural killer (NK) cells are an essential component of the innate immune system, and they play a crucial role in immunity against malignancies. Recent advances in our understanding of NK cell biology have paved the way for new therapeutic strategies based on NK cells for the treatment of various cancers. In this section, we will focus on NK cell immunotherapy, including the enhancement of antibody‐dependent cellular cytotoxicity, the manipulation of receptor‐mediated activation, inclusion criteria based on killer cell immunoglobulin‐like receptor (KIR) ligand mismatches, and adoptive immunotherapy with *ex vivo* expanded chimeric antigen receptor (CAR)‐engineered or engager‐modified NK cells. In contrast to T lymphocytes, donor NK cells do not attack any recipient tissues based on allogeneic human leukocyte antigens (HLAs), suggesting that NK‐mediated antitumor effects may be achieved without the risk of graft‐versus‐host disease (GvHD). Despite reports of clinical efficacy, the application of NK cell immunotherapy is limited. Developing strategies for manipulating NK cell products, host factors, and tumor targets are thus current subjects of diligent study. Research into the biology of NK cells has indicated that NK cell immunother‐ apy has the potential to become the forefront of cancer immunotherapy in the coming years.

**Keywords:** NK cell, KIRs, immunotherapy, HSC transplantation, genetic modification
