The NKp44-1 Isoform Is an Activating Receptor for PDGF-DD Expressed on Natural Killer Cells

Abstract

Background/Objectives: Natural killer (NK) cells are key innate lymphoid cells that restrict tumour progression by secreting proinflammatory cytokines and directly lysing malignant cells, with their activity tightly regulated by a balance of activating and inhibitory surface receptors. The natural cytotoxicity receptor NKp44 is induced on NK cells following stimulation with IL-2 or IL-15 and recognizes platelet-derived growth factor D (PDGF-DD) as a ligand. Mechanistic interpretation of NKp44 signalling upon PDGF-DD engagement is confounded by the existence of three distinct NKp44 isoforms (NKp44-1, -2, and -3), each capable of initiating divergent intracellular signalling cascades. Unlike N..