A Study to Evaluate the Effects of Interleukin-12 (rhIL-12) in HIV-Positive Patients With CD4 Cell Counts Less Than 50 Cells/mm3 or 300-500 Cells/mm3

The purpose of this study is to determine the tolerance and effectiveness of rhIL-12 in HIV-positive patients with CD4 cell counts less than 50 cells/mm3 versus 300-500 cells/mm3. This study will look at the ability of rhIL-12 to boost the immune system against HIV and HIV-associated bacterial infections in these patients. IL-12 is found naturally in the body and rhIL-12 is the commercially produced version. IL-12 may enhance anti-HIV immune system activity by increasing the number of cells that fight infection. IL-12 may also increase the body's ability to fight bacterial infections such as Mycobacterium avium complex (MAC).