<qa>  What is the CD4 count of HIV-positive patients on combination antiretroviral therapy- Human immunodeficiency virus HIV-positive patients on combination antiretroviral therapy are eligible if their HIV is under adequate control with an antiretroviral regimen that has been stable for 4 weeks, as long as the CD4 count is 300; appropriate studies will be undertaken in patients receiving combination antiretroviral therapy when indicated; patients on zidovudine or stavudine would not be eligible 