Background: Cytotoxic T lymphocytes (CTLS) are believed to be important in the control of HIV infection, because the emerging HIV-specific CTL response observed during primary infection follows a close temporal association with acute viral load reduction.
Objective: The aim of this study was to quantify HIV-specific CD8+ T cells in relation to viral load by using peptide / MHC tetrameric complexes.
Design: The study carried out in 24 treatment experienced HLA-A0201 HIV-1 patients with various CD4+ T cell counts and at different stages of infection. HLA-A0201 molecules were coupled to HIV gag (SLYNTVALI) and pol (ILKEPVHGV) specific peptides. Lymphocyte subpopulations were estimated with flow cytometry (FACScalibur).
Results: 1) The group with higher viral load had higher proportion of Ag specific CD8+ cells (p:0.051 for gag and p:0.042 for pol) than the group with undertectable viral load. 2) In most of the patients there was a greater proportion of CD8+ cells recognizing the gag epitope than the pol epitope.
Conclusions: 1) The viral replication in patients with higher viral load is probably required to maintain higher frequencies of Ag specific CD8+ T cells. 2) The lower proportion of CD8+ pol+ cells may reflect fewer reverse transcriptase epitopes than gag.
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