OUTLINE: This is a dose escalation study of interleukin-12 (rhIL-12). RhIL-12 therapy begins 3-5 weeks after discharge from the chemotherapy/stem cell transplant hospitalization or 2-3 weeks after completion of posttransplant radiation. Patients receive rhIL-12 subcutaneously twice a week for 12 consecutive weeks. Treatment continues in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients are treated at each dose level of rhIL-12. The maximum tolerated dose is defined as the dose at which no more than 1 of 6 patients experiences dose limiting toxicity. Patients are followed every 2 months after treatment.