Natural killer cell–mediated cytotoxicity (NK cell–mediated cytotoxicity)

Natural killer cell–mediated cytotoxicity is an innate immune effector process in which NK cells recognize and kill infected, stressed, or transformed cells through a balance of activating and inhibitory receptor signals, culminating in target-cell death via granule exocytosis (perforin and granzymes) and death ligands such as Fas ligand and TRAIL[10][1][5]. NK cell activation integrates inputs from receptors including CD16 for ADCC, the natural cytotoxicity receptors (NKp30, NKp44, NKp46), and C-type lectins such as NKG2D, while inhibitory receptors (KIRs, NKG2A) sensing HLA class I enforce self-tolerance and implement the missing-self paradigm[6][2][3]. Functionally, NK cytotoxicity proceeds through formation of an immunological synapse, cytoskeletal polarization, and directed degranulation to induce apoptosis; additional programmed death modes such as necroptosis or pyroptosis can also be engaged depending on context[5][4]. Clinically, enhancing NK cytotoxicity underlies therapeutic strategies including monoclonal antibodies that leverage ADCC, adoptive NK transfer, and receptor/ligand-directed engineering, with applications in cancer and viral infections but with challenges from tumor microenvironment suppression and heterogeneity of ligand expression[6][3][4].

Other names

NK cell cytotoxicityNK-mediated killingNK cell–mediated killingNatural killer cytotoxicity

Antibody-dependent cell-mediated cytotoxicity via CD16 (FcγRIIIa) triggering degranulation; Activation of NK receptors (e.g., NKp30, NKp44, NKp46, NKG2D) leading to perforin/granzyme release; Death receptor pathway via Fas ligand and TRAIL expression inducing apoptosis in targets; Modulation of inhibitory signaling via KIRs and NKG2A recognizing HLA class I (missing-self)