Genetically Modified Lymphocytes to Treat HIV-Infected Identical Twins - Study Modifications

Certain patients enrolled in NIH protocol 94-I-0206 at the Clinical Center may be eligible to participate in one or more of the following new options: * Donor/recipient extension phase - Both the recipient (HIV-infected twin) and donor (non-infected twin) will participate in this extension of the CD4-zeta gene therapy study. It will evaluate the safety and activity of infusing gene-modified CD4+ cells as well as the modified CD8+ cells. * Corticosteroid administration - A corticosteroid, such as prednisone, hydrocortisone or prednisolone, will be added to the interleukin-2 (IL-2) regimen for preventing or treating side effects of IL-2 such as fever and other flu-like symptoms. * Extended follow-up - A more intensive follow-up will be scheduled for patients with substantial numbers of lymphocytes that harbor the CD4-zeta gene. Every 3 months, participants will have blood tests and specialized tests of CD4 counts, HIV-1 viral load and numbers of circulating cells containing the CD4-zeta gene every 3 months\> the frequency of follow-up visits may be reduced as time goes by. * IL-2 continuation - Participants will continue to receive periodic treatment with IL-2 to see how long the genetically modified cells persist in the bloodstream and to evaluate the long-term response to IL-2. * Home treatment with interleukin-2 - Participants may receive future IL-2 treatment cycles at home. Home treatment involves less frequent data and safety monitoring and no medical evaluations at the Clinical Center except at the beginning of each cycle.