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Chainbinding Cytokines, Can Reverse the Defect in Generation of CD4 Effector T Cells from Naive T Cells of Aged Mice
Correspondence to: Laura Haynes, Trudeau Institute, P.O. Box 59, Saranac Lake, NY 12983. Tel:518-891-3080 ext. 143 Fax:518-891-5126 E-mail:lhaynes{at}trudeauinstitute.org.
Development of effectors from naive CD4 cells occurs in two stages. The early stage involves activation and limited proliferation in response to T cell receptor (TCR) stimulation by antigen and costimulatory antigen presenting cells, whereas the later stage involves proliferation and differentiation in response to growth factors. Using a TCR-transgenic (Tg+) model, we have examined the effect of aging on effector generation and studied the ability of
c signaling cytokines to reverse this effect. Our results indicate that responding naive CD4 cells from aged mice, compared with cells from young mice, make less interleukin (IL)-2, expand poorly between days 3 to 5, and give rise to fewer effectors with a less activated phenotype and reduced ability to produce cytokines. When exogenous IL-2 or other
c signaling cytokines are added during effector generation, the Tg+ cells from both young and aged mice proliferate vigorously. However, IL-4, IL-7, and IL-15 all fail to restore efficient effector production. Only effectors from aged mice generated in the presence of IL-2 are able to produce IL-2 in amounts equivalent to those produced by effectors generated from young mice, suggesting that the effect of aging on IL-2 production is reversible only in the presence of exogenous IL-2.
Key Words:
T cell receptor transgenic, CD4 cells, aging, IL-2,
c-binding cytokines
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