Natural killer cell receptors and innate immune pattern recognition pathways (NKRs and PRRs)

Natural killer (NK) cell receptors and innate immune pattern recognition pathways (PRRs) represent a broad category of molecular systems essential for the host's immediate defense against pathogens and transformed cells. NK cell receptors, such as killer cell immunoglobulin-like receptors (KIRs) and C-type lectin-like receptors (e.g., NKG2A, NKG2D), function by integrating activating and inhibitory signals to determine the threshold for NK cell-mediated cytotoxicity [1]. Pattern recognition receptors, including Toll-like receptors (TLRs) and NOD-like receptors (NLRs), detect conserved pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs), initiating signaling cascades that produce pro-inflammatory cytokines and bridge innate and adaptive immunity [2]. In therapeutic contexts, these pathways are targeted to enhance anti-tumor immunity; for example, monoclonal antibodies like monalizumab block inhibitory NKG2A receptors to unleash NK and CD8+ T cell activity [3]. Additionally, PRR agonists are developed as vaccine adjuvants or direct immunostimulants to convert immunologically "cold" tumors into "hot" tumors [4]. Dysregulation of these pathways is a hallmark of various pathologies, including chronic viral infections, where exhausted NK cells fail to clear pathogens, and cancer, where tumors exploit inhibitory receptors to evade immune detection [5]. Because this target entry encompasses multiple distinct receptor families and signaling cascades rather than a single molecule, it is classified as a pathway-level therapeutic focus [6]. [1] Vivier E, et al. (2018). "Innate lymphoid cells: 10 years on." Nature Reviews Immunology. [2] Janeway CA Jr, Medzhitov R. (2002). "Innate immune recognition." Annual Review of Immunology. [3] André P, et al. (2018). "Anti-NKG2A mAb Is a Checkpoint Inhibitor that Promotes Anti-tumor Immunity by Unleashing Both NK and CD8+ T Cells." Cell. [4] Kaczanowska S, et al. (2013). "TLR agonists: our best weapon against cancer?" Current Opinion in Immunology. [5] Lanier LL. (2005). "NK cell recognition." Annual Review of Immunology. [6] Sivori S, et al. (2019). "NK cell-based immunotherapy for hematological malignancies." Journal of Clinical Medicine.

Other names

NK cell receptor signalingInnate immune sensing pathwaysPattern recognition receptor (PRR) pathwaysNK cell activation and inhibition receptors

Modulation of NK cell activity through the blockade of inhibitory receptors (e.g., NKG2A, KIR) or the activation of stimulatory receptors; and the agonism of pattern recognition receptors (e.g., TLRs) to induce pro-inflammatory signaling and enhance antigen presentation.