Natural killer (NK) cells, a type of T lymphocyte cell, are major actors of the body’s 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 by preexistent body’s own and adaptive, newly developed 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. These studies concluded that there was a marked reduction in NK activity in patients with relapsed 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 NK cell driven responses worked better than ones who did not; however, therapeutic attempts to use this information to develop novel approaches have failed.
The NK field is currently in the stage still of gathering information and conceptualizing it into a set of insights that can then be refined and applied. It is not ready for routine clinical use.
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