Our findings showed that NK cells in SS display different features than those in healthy subjects, with one aspect being decreased CD56dimNK population number, down-modulation of NKG2D, and impairment of IFN-γ response, and the other revealing a preserved CD56bright NK population and the presence of mature, memory CD57+NKG2C+ NK cells. This evidence concerns the gene KLRK1 and synovial sarcoma.