Causes of Autoimmune Hepatitis. AIH occurs when your immune system mistakes your liver cells for foreign aggressors and creates antibodies to attack them. Doctors do not know precisely why this occurs. However, certain risk factors have been identified, including: 1  a family history of AIH.auses of Autoimmune Hepatitis. AIH occurs when your immune system mistakes your liver cells for foreign aggressors and creates antibodies to attack them. Doctors do not know precisely why this occurs. However, certain risk factors have been identified, including: 1  a family history of AIH.