T cell avidity is critical to viral clearance, but mechanisms of CD8 + T cell avidity maturation are poorly understood. Here, we find that IL-15 mediates two mechanisms of avidity maturation. (i) By selection at the population level, IL-15 promotes greater survival of high- compared with low-avidity cytotoxic T lymphocytes (CTLs). High-avidity CTLs express higher levels of IL-15Rα and persist longer by homeostatic proliferation. (ii) At the individual cell level, IL-15 induces higher levels of surface coreceptor CD8αβ, increasing functional avidity. IL-15 during priming selects or induces higher-avidity CTLs. Conversely, high-avidity CTLs are diminished in IL-15Rα knockout mice. These results provide an explanation of CD8 + T cell avidity maturation and may contribute to the design of novel vaccines.
|Number of pages
|Proceedings of the National Academy of Sciences of the United States of America
|Published - Oct 19 2004
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