CD25-expressing CD8+ T cells are potent memory cells in old age.
J Immunol
; 175(3): 1566-74, 2005 Aug 01.
Article
em En
| MEDLINE
| ID: mdl-16034095
ABSTRACT
We have recently described an IL-2/IL-4-producing CD8+CD25+ non-regulatory 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+CD25+ memory T cells frequently exhibit a CD4+CD8+ double-positive phenotype. The expression of the CD8 alphabeta 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+CD25- memory counterparts, thus indicating a shorter replicative history. CD8+CD25+ 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+CD25- 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+CD25+ and CD8+CD25- memory T cell populations, demonstrating a lineage relationship between CD25+ and CD25- memory CD8+ T cells. Our results suggest that CD25-expressing memory T cells represent an early stage in the differentiation of CD8+ 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.
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Base de dados:
MEDLINE
Assunto principal:
Idoso de 80 Anos ou mais
/
Receptores de Interleucina-2
/
Senescência Celular
/
Linfócitos T CD8-Positivos
/
Memória Imunológica
Limite:
Aged
/
Aged80
/
Humans
/
Middle aged
Idioma:
En
Ano de publicação:
2005
Tipo de documento:
Article