Natural Killer (NK) cell therapy is an emerging form of immunotherapy used in the treatment of various cancers and infectious diseases. The procedure involves the isolation, expansion, and infusion of NK cells, which are a type of lymphocyte with innate ability to destroy cancer cells and virally infected cells. Initially, NK cells are extracted from a suitable source, such as the patient (autologous therapy) or a healthy donor (allogeneic therapy), or are derived from stem cells. The source of NK cells may vary based on the specific therapeutic goal and patient’s condition. Once collected, these cells are expanded and activated ex vivo. This is typically achieved using cytokines like IL-2 or IL-15, and in some cases, feeder cells that enhance their proliferation and cytotoxic activity. Genetic engineering techniques can also be applied to enhance their efficiency and specificity towards target cells.

Once a sufficient number of active NK cells are achieved, they are prepared for infusion back into the patient. The patient may undergo conditioning treatment such as chemotherapy or radiotherapy to create a receptive environment for the NK cells and to reduce elements that might counter the therapy, such as regulatory immune cells. The NK cells are then administered into the patient via intravenous infusion. Post-infusion, patients are monitored for any adverse reactions and for signs of therapeutic response, such as reduction in tumor size or improvement in infection symptoms. This monitoring helps assess the therapy’s effectiveness and safety, allowing adjustments to be made for future treatments if necessary. NK cell therapy holds promise due to its specificity and lower risk of graft-versus-host disease, often associated with different types of adoptive cell therapies like CAR T-cell therapy.