Methods of treating an autoimmune disease such as rheumatoid arthritis, methods of increasing apoptosis of pro-inflammatory immune cells or synoviocytes, methods of increasing the quantity of the anti-inflammatory regulatory T cells, and methods of slowing the progression of inflammation in a subject include systemically administering to the subject a pharmaceutical composition including an effective amount of a TRAIL-conjugate. Preferably, the TRAIL-conjugate is effective for at least 3 days, more preferably at least 7 days, without being part of a nanocomplex that modulates the circulation half-life or release kinetics of the TRAIL-conjugate. Combination therapies including administering a second active agent, most preferably a TNF-α inhibitor, as well as pharmaceutical composition dosage units including a TRAIL-conjugate and a TNF-α inhibitor in an effective amount for a single once weekly dose for treatment of rheumatoid arthritis are also provided.