Both Interleukin-6 (IL-6) and Tumor necrosis factor-alpha (TNF-alpha) are substances naturally produced by the body's immune system. Evidence suggests that TNF-alpha production may be excessive or inappropriate in HIV-infected patients. Elevated TNF-alpha levels can result in increased IL-6 production and possibly increased HIV replication. TNFR:Fc is a modification of a natural substance that binds to TNF-alpha and neutralizes its activity. It is postulated that TNFR:Fc may result in decreased activity of TNF-alpha and lower IL-6 levels. HIV-infected patients who receive Interleukin-2 (IL-2) have been shown to have higher TNF-alpha and IL-6 levels than those who do not receive IL-2. It is thought that these higher levels of TNF-alpha and IL-6 may contribute to some of the flu-like symptoms experienced by patients receiving IL-2. By decreasing the amount of IL-6 in the body and by decreasing the action of TNF-alpha in the body, TNFR:Fc may have a role in the treatment of HIV disease or in alleviating some of the symptoms related to IL-2 administration.