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Volume 6 Supplement 3

AIDS Vaccine 2009

P16-27.Optimization of the expansion of antigen-specific CD8+ T-cells for use in a viral suppression assay


CD8+ T-cells have long been shown to be important for control of HIV-1 infection, though it is clear that not all CD8+ T-cell responses are equal. For the best chance of producing a successful vaccine, it is crucial to define which responses lead to better disease outcomes. Many studies have correlated HIV-specific T-cell responses with slower HIV disease progression; however, a causal relationship has not been clearly defined. Tetramers to antigen-specific cells allow enumeration, characterization and separation of cell populations, allowing comparison of their viral suppressive capabilities in downstream assays.


Tetramers were used to enumerate HIV-1 antigen-specific CD8+ T-cells in PBMCs from HIV infected subjects, on a BD LSR-II flow cytometer. A protocol for expansion of these epitope-specific cells was developed in control samples using the CMV peptide NLVPMVATV due to its immunodominance in North America. Cells were stimulated for 10 days with varying concentrations of IL-2, IL-7 and IL-15 along with the tetramer-matched peptide to elucidate optimal expansion conditions.


Initially, ~0.5%–1.5% of CD8+ T-cells bound to HIV-1 specific tetramers in HIV-1 infected subjects. These low cell numbers identified a need for expansion of the cells for use in downstream assays. In our protocol, addition of IL-15 and peptide results in an increase of tetramer+ cells from 3.5% to 85% of total CD8+ T-cells, while IL-2 and IL-7-induced responses were less robust. Increasing the concentrations or adding multiple cytokines at once decreased the population of tetramer+ T-cells to less than 1%.


These results indicate that antigen-specific T-cells can be expanded to high levels for use in subsequent assays, such as a study of their HIV-1 suppressive capabilities. This will provide a direct link between specific CD8+ T-cells and viral control, which will be key in determining which responses are most likely to be effective in an HIV-1 vaccine.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Herman, M., McKinnon, L., Meyers, A. et al. P16-27.Optimization of the expansion of antigen-specific CD8+ T-cells for use in a viral suppression assay. Retrovirology 6 (Suppl 3), P256 (2009).

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