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2. all time points tested, even when viral replication was undetectable due to therapy. Subjects with detectable gp120 had higher levels of plasma IL-6, IL-10, and TNF-. There was no difference in the level of T cell activation, proliferation, or apoptosis in subjects with gp120 compared to those without. We conclude that persistent expression of gp120 occurs in a subset of individuals. Furthermore, the presence of gp120 is usually associated with higher levels of plasma IL-6, IL-10, and TNF-, which may contribute to immune dysfunction during early HIV contamination. == Introduction == Events that occur during the earliest stageof HIV contamination are thought to contribute to the subsequent dysfunction of HIV-specific immune responses. In the weeks following contamination, the computer virus replicates to peak levels, usually in excess of one million viral copies per milliliter of blood, before declining to a set point.1During this early phase of infection, immune system dysfunction becomes apparent. There is a significant loss of CD4+T cells, especially in the gut, and an up-regulation of proinflammatory and immunoregulatory cytokines, including IL-10, IL-6, and TNF-.2,3Additionally, virus-specific CD4+T cell responses are typically weak or absent.4The mechanisms that account for Sulfabromomethazine these defects are not completely understood. We hypothesize that this viral envelope protein, gp120, contributes to the immunological dysfunction that is observed during early HIV contamination. The HIV envelope Sulfabromomethazine glycoprotein is composed of two models, gp120 and gp41, which are held together by noncovalent interactions. This allows the gp120 subunit to readily be shed from virions and infected cells.5,6Binding of gp120 to CD4 on the surface of T cells, dendritic cells, and macrophagesin vitroresults in the production of cytokines including interleukin (IL)-6, IL-10, interferon (IFN)-, tumor necrosis factor (TNF)-, IFN-, and IL-1.7Furthermore, it inhibits T cell functions through several mechanisms including down-regulation of the costimulatory molecule, CD40L, a decline in the production of IL-2, and decreased antigen-specific proliferation.7HIV gp120 induced T cell dysfunction has also been observed in murine8and nonhuman primate models.9Furthermore, binding of gp120 to human CD4+T cells has been indirectly observedex vivoand correlated with decreased proliferative responses.10The relevance of these observations to the pathogenesis of HIV infection has been debated.11In particular, it is not known if the amount of gp120 in an infected individual is sufficient to cause immune system dysfunction. Given that computer virus replication is at its highest during acute contamination, we hypothesize that this production of gp120 is sufficient during this time to contribute to the impairment of HIV-specific immune responses. The purpose of this study was to measure the concentration of gp120 in plasma during acute and early HIV contamination and determine whether gp120 was associated with measures of immune dysfunction including production of proinflammatory and immunoregulatory cytokines, T cell activation and apoptosis, and lack of HIV-specific T cell proliferation. == Materials and Methods == == Subjects and samples == Subjects were chosen from a cohort of individuals enrolled in an observational study of acute and early HIV contamination at Massachusetts General Hospital (MGH). Acute HIV contamination was defined by a negative HIV-1/2 enzyme-linked immunosorbent assay (ELISA) or a negative or indeterminate HIV-1 Western blot and the presence of detectable HIV-1 RNA. Individuals who did not meet these criteria but had recent contamination as evidenced by a nonreactive detuned ELISA12or a clinical history consistent with HIV contamination within the last 12 months were considered to have early HIV contamination. One hundred and nine subjects were chosen based on the availability of samples prior to or around the time of seroconversion. Of these, 37 were in the acute phase of contamination and 72 were in the early phase of contamination. The MGH clinical laboratories performed all HIV RNA viral loads Sulfabromomethazine and CD4+T cell counts. Ten uninfected subjects were enrolled onto a similar protocol and used as controls. This study was approved by the MGH Human Subjects Committee and all subjects gave informed consent prior to participation. == Isolation of cells == Peripheral blood mononuclear cells (PBMCs) were isolated from Mouse monoclonal to ABCG2 ACD-treated whole Sulfabromomethazine blood using a Ficoll-Hypaque (Sigma, St. Louis, MO) density gradient according to the manufacturer’s instructions. The plasma layer was removed and stored in aliquots at 80C. == gp120 ELISA == The presence of gp120 in plasma was measured by ELISA. Plates were coated with 1 g/ml of a mixture of three human monoclonal antibodies against gp120 including 17b, A32,.