Group I: IL-2 every 12 hours for 5 days every 8 weeks. Group II: IL-2 every 12 hours for 5 days every 8 weeks (higher IL-2 dose). Group III: Control group receiving no therapy. Patients must complete a minimum of 3 8-week cycles of treatment. Twelve patients are randomized to each arm. Following study completion, Group I and II patients may elect to continue receiving IL-2 during follow-up or as part of an additional protocol based on the results of this study.