Yet another role for natural killer cells: Cytotoxidty in immune regulation and viral persistence

摘要

At early times during viral infections, natural killer (NK) cells can contribute to direct antiviral defense (1, 2). the effect is most dramatic when they are stimulated to release the contents of their cytolytic granules for lysis of virus-infected target cells. Type 1 interferons (IFNs), produced during innate responses to infections, induce elevated NK cell cytotoxicity. Killing, however, is ultimately dependent on signaling through NK activating receptors by ligands expressed on target cell surfaces. A complex repertoire of germ-line genes encodes NK receptors (2). Some of these are conserved, whereas others are poly-genic and polymorphic. At later times, adaptive immunity, such as that delivered by cytotoxic CD8 T cells, mediates protection.