| Summary: | <p>Abstract</p> <p>Background</p> <p>Effective highly active antiretroviral therapy (HAART) reduces human immunodeficiency virus (HIV) replication, restores CD4<sup>+ </sup>T lymphocyte counts and greatly reduces the incidence of opportunistic infections. While this demonstrates improved generalized immune function, rapid rebound to pre-treatment viral replication levels following treatment interruption indicates little improvement in immune control of HIV replication. The extent to which HAART can normalize HIV-specific CD8<sup>+ </sup>T cell function over time in individuals with chronic infection remains an important unresolved issue. In this study, we evaluated the magnitude, general specificity and character of HIV specific CD8<sup>+ </sup>T cell responses at four time points across 2-9 years in 2 groups of chronically infected individuals separated on the basis of either effective antiretroviral suppression or ongoing replication of HIV.</p> <p>Methods</p> <p>Peripheral blood mononuclear cells (PBMC) were stimulated with overlapping 15mer peptides spanning HIV Gag, Pol, Env and Nef proteins. Cells producing interferon-γ (IFN-γ) or interleukin-2 (IL-2) were enumerated by ELISPOT and phenotyped by flow cytometry.</p> <p>Results and Conclusions</p> <p>The magnitude of the HIV-specific CD8<sup>+ </sup>T cell response ranged from < .01 to approximately 1.0% of PBMC and was significantly greater in the group with detectable viral replication. Stronger responses reflected higher numbers of CD8<sup>+</sup>CD45RA<sup>- </sup>effector memory cells producing IFN-γ, but not IL-2. Magnitude, general specificity and character of the HIV-specific CD8<sup>+ </sup>T cell response changed little over the study period. While antiretroviral suppression of HIV in chronic infection reduces HIV-specific CD8<sup>+ </sup>T cell response magnitude in the short term, it had no significant effect on response character over periods up to 9 years.</p>
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