Damage from autoimmune diseases can be prevented or minimized by positioning a plurality of electrodes in or on a subject's body, and applying an AC voltage between the plurality of electrodes so as to impose an alternating electric field through the tissue that is being attacked by the autoimmune disease and/or draining lymph nodes associated with that tissue. The frequency and field strength of the alternating electric field are selected such that the alternating electric field inhibits proliferation of T cells in the tissue to an extent that reduces damage that is caused by the autoimmune disease.