CD25-Expressing CD8 super(+) T Cells Are Potent Memory Cells in Old Age

We have recently described an IL-2/IL-4-producing CD8 super(+)CD25 super(+) nonregulatory memory T cell population that occurs in a subgroup of healthy elderly persons who characteristically still have a good humoral response after vaccination. The present study addresses this specific T cell subset...

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Bibliographic Details
Published in:The Journal of immunology (1950) 2005-08, Vol.175 (3), p.1566-1574
Main Authors: Herndler-Brandstetter, Dietmar, Schwaiger, Susanne, Veel, Ellen, Fehrer, Christine, Cioca, Daniel P, Almanzar, Giovanni, Keller, Michael, Pfister, Gerald, Parson, Walther, Wuerzner, Reinhard, Schoenitzer, Diether, Henson, Sian M, Aspinall, Richard, Lepperdinger, Guenter, Grubeck-Loebenstein, Beatrix
Format: Article
Language:English
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Summary:We have recently described an IL-2/IL-4-producing CD8 super(+)CD25 super(+) nonregulatory memory T cell population that occurs in a subgroup of healthy elderly persons who characteristically still have a good humoral response after vaccination. The present study addresses this specific T cell subset and investigates its origin, clonal composition, Ag specificity, and replicative history. We demonstrate that CD8 super(+)CD25 super(+) memory T cells frequently exhibit a CD4 super(+)CD8 super(+) double-positive phenotype. The expression of the CD8 alpha beta molecule and the occurrence of signal-joint TCR rearrangement excision circles suggest a thymic origin of these cells. They also have longer telomeres than their CD8 super(+)CD25 super(-) memory counterparts, thus indicating a shorter replicative history. CD8 super(+)CD25 super(+) memory T cells display a polyclonal TCR repertoire and respond to IL-2 as well as to a panel of different Ags, whereas the CD8 super(+)CD25 super(-) memory T cell population has a more restricted TCR diversity, responds to fewer Ags, and does not proliferate in response to stimulation with IL-2. Molecular tracking of specific clones with clonotypic primers reveals that the same clones occur in CD8 super(+)CD25 super(+) and CD8 super(+)CD25 super(-) memory T cell populations, demonstrating a lineage relationship between CD25 super(+) and CD25 super(-) memory CD8 super(+) T cells. Our results suggest that CD25-expressing memory T cells represent an early stage in the differentiation of CD8 super(+) cells. Accumulation of these cells in elderly persons appears to be a prerequisite of intact immune responsiveness in the absence of naive T cells in old age.
ISSN:0022-1767