Changes

NK cells do not develop in the thymus and represent 5-10% of the circulating lymphocytes. They recognise and kill transformed cells by releasing perforins and granzymes which create channels in the target cell membrane causing lysis.  They express the markers CD16, CD56 and CD94.

NK cells do not develop in the thymus and represent 5-10% of the circulating lymphocytes. They recognise and kill transformed cells by releasing perforins and granzymes which create channels in the target cell membrane causing lysis.  They express the markers CD16, CD56 and CD94.

Natural Killer cells also play a role in [[Adaptive Immune System - WikiBlood#Adaptive Immunity to Viruses|'''Antibody-Dependent Cell-mediated Cytotoxicity''']]

Natural Killer cells also play a role in [[Adaptive Immunity to Viruses|'''Antibody-Dependent Cell-mediated Cytotoxicity''']]

===NK Receptors===

===NK Receptors===

* Some viruses down-regulate MHC expression of the infected cell

* Some viruses down-regulate MHC expression of the infected cell