1. CD25-expressing CD8+ T cells are potent memory cells in old age
- Author
-
Daniel Cioca, Dietmar Herndler-Brandstetter, Günter Lepperdinger, Ellen Veel, Susanne Schwaiger, Beatrix Grubeck-Loebenstein, Giovanni Almanzar, Gerald Pfister, Walther Parson, Michael Keller, Reinhard Würzner, Sian M. Henson, Richard Aspinall, Christine Fehrer, and Diether Schönitzer
- Subjects
Isoantigens ,Immunology ,Receptors, Antigen, T-Cell ,Down-Regulation ,chemical and pharmacologic phenomena ,Biology ,CD8-Positive T-Lymphocytes ,Lymphocyte Activation ,Immunophenotyping ,Interleukin 21 ,Immune system ,Antigen ,T-Lymphocyte Subsets ,medicine ,Immunology and Allergy ,Cytotoxic T cell ,Humans ,IL-2 receptor ,Intestinal Mucosa ,L-Selectin ,Phytohemagglutinins ,Cells, Cultured ,Cellular Senescence ,Aged ,Cell Proliferation ,Aged, 80 and over ,T-cell receptor ,Cell Membrane ,hemic and immune systems ,Receptors, Interleukin-2 ,HLA-DR Antigens ,Middle Aged ,Molecular biology ,medicine.anatomical_structure ,CD4 Antigens ,Interleukin-2 ,Memory T cell ,Immunologic Memory ,CD8 ,Cell Division - Abstract
We have recently described an IL-2/IL-4-producing CD8+CD25+ 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+CD25+ memory T cells frequently exhibit a CD4+CD8+ double-positive phenotype. The expression of the CD8 αβ 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.
- Published
- 2005