Human naive T cells activated by cytokines differentiate into a split phenotype with functional features intermediate between naive and memory T cells |
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Authors: | Unutmaz Derya; Baldoni Fabiana; Abrignani Sergio |
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Institution: | Immunobiology Research Institute Siena IRIS, Via Fiorentina 1, 53100 Siena Italy |
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Abstract: | We have recently shown that CD45RA+CD4+ naive T cells can beactivated to proliferate by a combination of IL-2, TNF- andIL-6, but, at variance with TCR-medlated activation, they donot acquire the CD45RO molecule. This prompted us to investigatethe phenotype of these cells and the functional features theydisplay upon TCR stimulation. Naive T cells expanded by cytokines,though remaining CD45RA+ express a variety of activation andadhesion molecules which are peculiar to effector or memoryT cells. Naive cells primed by cytokines, when activated withantl-CD3 mAb, produce a broad spectrum of cytokines, expressCD40 ligand, but are unable to help B cells for Ig synthesis.A subset of CD4+CD45RA + RO– T cells with a phenotype(HLA-DR–, VLA-2+ or IL-2R+) similar to that of cells activatedby cytokines In vitro can be found In vivo. These results demonstratethat activation signals delivered by cytokines, in the absenceof TCR stimulation, can activate naive T cells to proliferateand differentiate into a split phenotype withelements common to both naive and memory T cells. This novelantigen-Independent activation may help to maintain the naiveT cell repertoire and facilitate the antigen-responsivenessof naive T cells. |
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Keywords: | CD40 ligand effector function IL-2 IL-4 IL-6 survival TNF- " target="_blank">gif" ALT="{alpha}" BORDER="0"> |
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