The present invention provides a method for achieving normal levels of cellular apoptosis in non-transformed cells of a patient by administering to the patient a therapeutically effective amount of purified TRAIL ligand or active fragment thereof. In particular, such method is provided to a patient suffering from an autoimmune disease or condition, such as arthritis, encephalomyelitis or multiple sclerosis or autoimmune inflammation in the CNS. The present invention further provides a method of blocking the activity of an endogenous TRAIL receptor or inhibitor in a patient by administering to the patient a therapeutically effective amount of a purified TRAIL agonist, in an amount sufficient to enhance the patient's level of TRAIL ligand. In particular, such method is provided to enhance ameliorate or restore cellular apoptosis in non-transformed cells of the patient.