These experiments have sought to better understand the pathogenesis of HIV infection by examining multiple characteristics of infected cells in both the peripheral blood and lump node tissue. The lymphoid organs serve as a protected reservior of HIV infection where virus resides even when no virus can be found in the blood of patients on successful antiretroviral therapy. These studies have compared the two compartments for the amount of virus that is present, the relationships of populations of cells, and other features of the cells such as their level of immune stimulation and the number of receptors on their surface which permits HIV entry into the cell. Subjects undergo excisional lymph node biopsy and have samples of peripheral blood taken at least two time points; one prior to initiating a new antiretroviral therapy and at a later date after 6 to 18 months of therapy. It is anticipated that new insights into how antiretroviral therapy controls HIV infection will be gained and that this knowledge can be applied to novel approaches to treating AIDS.