This phase I/II study will evaluate the safety, immunologic effects, and potential efficacy of repeated infusions of syngeneic lymphocytes obtained from HIV-1 seronegative identical twins given in the setting of maximum anti-retroviral therapy. Unfractionated lymphocytes from each seronegative twin will be obtained by lymphocytapheresis and directly transferred to the HIV-1 seropositive twin. Four separate lymphocytaphereses and transfers will be performed over one week, and this cycle may be repeated as frequently as every 8 weeks for a total of up to 6 cycles. The recipient twin will be monitored for general health status, immunologic improvement, depletions within the CD4+ T-cell repertoire, and HIV-1 viral load.