No major differences in the functional profile of HIV Gag and Nef-specific CD8+ responses between long-term nonprogressors and typical progressors.

The mechanism explaining the failure of HIV-specific CD8(+) T cell responses to successfully control HIV replication remains elusive. A total of 83 drug-naive HIV-infected individuals, 27 of whom were long-term nonprogressors (LTNP), was examined. The ability of CD8(+) T lymphocytes to produce three different cytokines (MIP-1beta, TNF-alpha, IL-2) in response to HIV Gag and Nef peptides and to polyclonal stimuli and the ability of HIV-specific CD8(+) T cells to expand in vitro were evaluated by multiparameter flow cytometry.

Coinfection with hepatitis C virus increases lymphocyte apoptosis in HIV-infected patients.

To test the role of hepatitis C virus (HCV) in CD4 cell depletion in human immunodeficiency virus (HIV)-coinfected patients, T cell apoptosis was measured by annexin V labeling in 31 HIV-infected and 30 HIV-HCV-coinfected patients who were not receiving antiretroviral therapy. Apoptosis in naive CD4(+) T cells and in naive and memory CD8(+) T cells was significantly higher in HIV-HCV-coinfected than in monoinfected patients.

Immunological and virological effects of structured treatment interruptions following exposure to hydroxyurea plus didanosine.

Both hydroxyurea (HU) and structured treatment interruptions (STI) have been investigated as therapeutic approaches to enhance immune responses in chronically HIV-infected individuals. HIV-specific T cell responses as well as T cell activation were analyzed longitudinally in 31 HIV-infected individuals who had been treated for the prior 12 months with didanosine (ddI) plus HU and thereafter completed three STI cycles consisting of 2 months off and 2 months on ddI-HU. Similar increases in plasma HIV-RNA were seen in each of the three cycles off therapy, whereas CD4 counts remained fairly stable along the study period.

CD4+ T cell recovery beyond the first year of complete suppression of viral replication during highly active antiretroviral therapy is not influenced by CD8+ T cell activation.

CD38 expression on CD8(+) T cells was longitudinally assessed in 31 human immunodeficiency virus (HIV)-infected persons with undetectable plasma viremia who had undergone highly active antiretroviral therapy (HAART) for 12 months and were followed for a mean of 30 months thereafter. Overall, CD4(+)T cell counts increased during follow-up, whereas CD38 expression remained stable. However, a subset of patients showed declines in CD38 expression, and, conversely, another subset showed increases in CD38 expression.

Differential upregulation of CD38 on different T-cell subsets may influence the ability to reconstitute CD4+ T cells under successful highly active antiretroviral therapy.

Background: Immune activation is an independent surrogate marker of CD4 T-cell depletion in HIV-infected patients. Highly active antiretroviral therapy (HAART) reduces disease progression as a direct consequence of suppressing HIV replication. Immune function does not normalize completely in most subjects on HAART, however, perhaps reflecting residual HIV replication.