Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Primary Biliary Cirrhosis ?
    ### Response:
    The causes of primary biliary cirrhosis are unknown. Most research suggests it is an autoimmune disease. The immune system protects people from infection by identifying and destroying bacteria, viruses, and other potentially harmful foreign substances. An autoimmune disease is a disorder in which the bodys immune system attacks the bodys own cells and organs.
    