MHC-unrestricted cytotoxicity

MHC-unrestricted cytotoxicity is a fundamental immune mechanism where effector cells, primarily Natural Killer (NK) cells and gamma-delta T cells, identify and destroy abnormal cells without the requirement for antigen presentation by Major Histocompatibility Complex (MHC) molecules (Vivier et al., 2011, Science). This process is governed by a sophisticated balance of signals from activating receptors, such as NKG2D and Natural Cytotoxicity Receptors (NCRs), and inhibitory receptors like Killer-cell Immunoglobulin-like Receptors (KIRs) (Lanier, 2005, Annual Review of Immunology). In oncology, this mechanism is critical for targeting 'stealth' tumors that downregulate MHC expression to evade classical CD8+ T-cell detection (Ljunggren & Karre, 1990, Immunology Today). Therapeutic strategies leveraging this process include CAR-NK cell therapies, bispecific killer cell engagers (BiKEs), and checkpoint inhibitors like Monalizumab, which blocks the inhibitory NKG2A receptor to enhance NK cell activity (André et al., 2018, Cell). While highly promising for broad-spectrum immunotherapy, challenges include maintaining effector cell persistence in the tumor microenvironment and managing potential systemic inflammatory toxicities (Liu et al., 2020, NEJM).

Other names

Non-MHC-restricted cytotoxicityInnate-like cytotoxicityNK-cell-mediated killingMHC-independent lysis

Activation of innate-like immune cells, such as Natural Killer (NK) cells and gamma-delta T cells, to recognize and eliminate target cells through a balance of activating and inhibitory receptors independently of MHC-peptide presentation.