LAUSR

According to PubMed (https://www.ncbi.nlm.nih.gov/pubmed/ NK%20cell), there are approximately 59,000 citations for "NK cell" (Fig. 1A), beginning in the first half of the 20th Century with variations onmalignant histocytic reticulosis followed by reference to the evidently unrelated Nikolaĭ Konstantinovich Kol'tsov on the centennial of his birth in 1972 ! However, the “Natural Killer cells”we know and love really began to be understood in the 70s (Fig. 1A,B), alongside other lymphocyte subsets. Early experiments defined NK cells and established NK capability in ‘natural killing’ and antibody-dependent cell-mediated cytotoxicity assays using NK cells from mice and man. This included pioneering work of Hans Wigzell and colleagues as well as Laurie Glimcher and Harvey Cantor in mice [1–3], Puissant, Halldén and their colleagues in man, and Ronald Herberman et al. with both species and more [4–7]. Excellent current reviews written by some of the other key contributors since, further comprehensively describe the history and recent status of NK cell research [8–14]. There have been 2 waves of increases in publications on bona fide ‘Natural Killer cells (Fig. 1A), up to the end of the 1980s and after a ‘trough’ around 1990. So we could perhaps be considered currently in the renaissance of NK cells, in whichmolecular, in vivo and structural details as well as translational understanding have blossomed: NK cells are returning back from the bench to patients. Importantly the refined understanding of this important cytotoxic cell are allowing them to emerge as a promising therapeutic which is now seeing rapid advancement. This issue of Clin. Immunology brings together a series of reviews and papers by groups involved all aspects of ‘NK cell-ology’. These include the latest understanding on NK cells [21] and NK cells in vivo [23] as well as from groups involved in clinical trials related to NK cells [15, 20]. These trials have so far mostly relied on either specific matching of KIR haplotypes in thes context of transplantation or adoptive NK cell transfer since the beginning of the 21st century [8,10–12,15,20], no easy task, sinceNK cells donot rely only on IL-2 for their rapid expansion, unlike T cells. Trials with adoptive transfers to date have been mostly in various solid and especially hematological malignancies [8, 10–12,15,20], and there has been great innovation in the realm of adoptive transfer cell expansion [15]. Other NK-related approaches are underway and will likely lead to precise clinical applications [20]. Also included is a review covering the expanding understanding of the cell biology of NK [21]. Further reviews / papers cover NK cell involvement in spectrum of other diseases [16–19]. Finally there are reports of how to monitor and visualize murine and human NK cells [22,23]. More specifically, Lee et al. [15] discuss the direct treatment of cancer patients with NK-related therapies and how the contrasting approaches have yielded distinct outcomes. Viel et al. [16] describe NK cells in obese subjects and how NK cells might contribute to critical