Natural killer (NK) cells are major actors of innate immune responses against viruses, bacteria, parasites, and other mediators of pathology such as malignant transformation. These cells are also directly implicated in the link between innate and adaptive immunity, shaping T-cell responses. It is now obvious that manipulation of this lymphocyte subset could be the basis of new therapeutic approaches for cancer and/or pathogen-driven pathology. There is an interest in these cells in reproductive medicine, which is not a focus of our discussion.
There is some older evidence that loss of NK activity as an indicator of relapse in acute leukemia. They concluded that there was a marked reduction in NK activity in patients with active leukemia when compared with healthy controls, and that NK activity substantially
improved in complete remission. What this means for clinical medicine is not clear. Patients with CD20+ follicular lymphoma fared better when treated with the humanized anti-CD20 monoclonal antibody rituximab if their FcγRIIIa gene had a polymorphism that resulted in higher affinity for rituximab and enhanced ADCC activity in vitro; however, therapeutic attemtps to use this information have failed.
The NK is currently in the stage of gathering information and conceptualizing it into a set of insights that can then be studied. It is not ready for routine clinical use.
Dearden CE, Johnson R, Pettengell R, Devereux S, Cwynarski K, Whittaker S, McMillan A Guidelines for the management of mature T-cell and NK-cell neoplasms (excluding cutaneous T-cell lymphoma).Br J Haematol. 2011 May;153(4):451-85.
Caligiuri MA. Human natural killer cells.Blood. 2008 Aug 1;112(3):461-9.
Khan KD, Emmanouilides C, Benson DM Jr., et al. A phase 2 study of rituximab in combination with recombinant interleukin-2 for rituximab-refractory indolent non-Hodgkin’s lymphoma. Clin Cancer Res 2006;12:7046-7053.
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