The study medication, rhIL-12, is an experimental drug that hasn't been approved by the Food and Drug Administration (FDA). The purpose of this two-part study is to determine the safety and tolerance of several doses of rhIL-12, which will be given under the skin by injection. IL-12 is a type of protein that is naturally produced by certain types of cells of the immune system and is believe to be important for immune function. About 54 volunteers will take part in this ten-week study in HIV-infected people. Although rhIL-12 has no direct effect against HIV, rhIL-12 may improve the ability of the immune system to fight the HIV virus.