<prompt> The following feature is common to both cytotoxic T cells and NK cells?Synthesizes antibodiesRequire antibodies to be present for actionEffective against virus infected cellsRecognize antigen in association with HLA class II markers  <response>: Common to both cytotoxic T cells and NK cells is affectivity against virus-infected cellsNK cells:1st line of defense against virus-laden cells and neoplastic cellsCytotoxicity is not MHC restricted Cytotoxic T cells:They are antigen-specific T cells whose function is to produce antigen-specific lysis of target cells by the direct cell to cell contactAre usually CD class I MHC restricted T cellsAre impoant in defense against virus infections of tissues Ref: Harrisons 18e p2688,2669 