Primary biliary cirrhosis (PBC) is an organ-specific autoimmune liver disease characterized by the presence of antimitochondrial antibodies and the destruction of small intrahepatic bile ducts with portal inflammation.In previous study,we reported that there was a marked increased in the frequency and number of both blood and liver NK cells in PBC patients.Herein we also discovered the number of NK was increased in dominant-negative transforming growth factor β receptor Ⅱ (dnTβRⅡ) mice, which were acceptable mouse model of PBC, and these NK cells highly expressed activated surface markers.