Human Natural Killer Cells: Origin, Receptors, Function, and Clinical Applications

Abstract

Natural killer (NK) cells are important effectors playing a relevant role in innate immunity, primarily in tumor surveillance and in defenses against viruses. Human NK cells recognize HLA class I molecules through surface receptors (KIR and NKG2A) that inhibit NK cell function and kill target cells that have lost (or underexpress) HLA class I molecules as it occurs in tumors or virus-infected cells. NK cell activation is mediated by an array of activating receptors and co-receptors that recognize ligands expressed primarily on tumors or virus-infected cells. In vivo anti-tumor NK cell activity may be suppressed by tumor or tumor-associated cells. Alloreactive NK cells (i.e. those that are not inhibited by the HLA class I alleles of the patient) derived from HSC of haploidentical donors play a major role in the cure of high-risk leukemia, by killing leukemia blasts and patient's DC, thus preventing tumor relapses and graft-versus-host disease. The expression of the HLA-C2-specific activating KIR2DS1 may also contribute to NK alloreactivity in patients expressing C2 alleles. A clear correlation has been proven between the size of the alloreactive NK cell population and the clinical outcome. Recently, haplo-HSCT has been further improved with the direct infusion, together with HSC, of donor-derived, mature alloreactive NK cells and TCRγδ⁺ T cells - both contributing to a prompt anti-leukemia effect together with an efficient defense against pathogens during the 6- to 8-week interval required for the generation of alloreactive NK cells from HSC.

Toxicological Implications and Inflammatory Response in Human Lymphocytes Challenged with Oxytetracycline

“…In this context, it is known that IFN‐γ represents the main cytokine involved in the immune response 19, as well as a crucial element in the onset of impaired tissue homeostasis conditions, typically related to autoimmunity or chronic inflammation 23, 24, 25, 26, 27, 28, 29, 30, 31.…”

Antitumor Weapons of the Immune System

“…NK buňky NK buňky (natural killer -"přirozený zabí-ječ") byly popsány jako lymfocyty, které jsou schopny rychle (bez předchozí stimulace, proliferace a diferenciace) zabí-jet ně kte ré nádorové a virově infi kované buňky, a to mechanizmy velmi podobnými těm, které používají i cytotoxické T lymfocyty (Tc, viz níže) [6]. Na rozdíl od útoku imunitního systému [11].…”

Pro- and anti-inflammatory actions in coronary artery disease : with focus on CD56+ T cells and Annexin A1

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