| Autor: |
Dobber, Ruud, Tielemans, Margret, de Weerd, Hellen, Nagelkerken, Lex |
| Zdroj: |
International Immunology; Aug1994, Vol. 6 Issue 8, p1227-1234, 8p |
| Abstrakt: |
Aging is accompanied by an increased fraction of memory CD4 T cells. Despite the fact that human memory cells have been reported to produce high levels of IL-2, studies in mice and man indicate an age-related decline in IL-2 production. In the present study, we examined whether these conflicting results depend on the activation pathway employed in a comparison of phenotypically distinct CD4 T cells from young and aged mice. Our data indicate an age-related decline in IL-2 production by CD4 T cells when the cells were stimulated with concanavalin A in the presence of accessory cells or the combination of immobilized anti-CD3 and soluble anti-CD28. However, when CD4 T cells were only stimulated with Immobilized anti-CD3, an age-related increase in IL-2 production was observed. This age-related increase in IL-2 could be attributed to the ability of CD4 T cells from aged mice to produce IL-4 on this stimulation, since anti-IL-4 inhibited the IL-2 production In these cultures to levels found with cells from young mice. The addition of exogenous IL-4 greatly enhanced the IL-2 production of CD4 T cells from young mice to levels far beyond that of the aged counterparts, emphasizing the dominant role of IL-4 In the induction of IL-2 stimulated with immobilized anti-CD3. No differences were observed in the activation requirements of Mel14 CD4 T cells from young and aged mice. However, Mel14 CD4T cells from aged mice were functionally and phenotypically more mature than their young counterparts, since they were capable of IL-2 and IL-4 production in response to antl-CD3 without the need of CD28 triggering and expressed Pgp-1 and ICAM-1 in a higher density. Our data indicate therefore that Mel14 is not a stable marker for naive CD4 T cells and might not be appropriate to distinguish these cells from memory cells. [ABSTRACT FROM PUBLISHER] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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