 - Both males and females are eligible, but sexually active females at risk of pregnancy of childbearing potential must agree to use an effective method of avoiding pregnancy which includes oral or implanted contraceptives, IUD, female condom, diaphragm with spermicide, cervical cap, abstinence, use of a condom by the sexual partner or sterile sexual partner beginning 30 days before the first study infusion and continuing through 60 days after the final study infusion. 