TY - JOUR
T1 - IL-21 promotes differentiation of naive CD8 T cells to a unique effector phenotype
AU - Casey, Kerry A.
AU - Mescher, Matthew F
PY - 2007/6/15
Y1 - 2007/6/15
N2 - IL-21, the most recently described member of the common γ-chain cytokine family, is produced by activated CD4 T cells, whereas CD8 T cells express the IL-21 receptor. To investigate a possible role for IL-21 in the priming of naive CD8 T cells, we examined responses of highly purified naive OT-I CD8 T cells to artificial APCs displaying Ag and B7-1 on their surface. We found that IL-21 enhanced OT-I clonal expansion and supported development of cytotoxic effector function. High levels of IL-2 did not support development of effector functions, but IL-2 was required for optimal responses in the presence of IL-21. IL-12 and IFN-α have previously been shown to support naive CD8 T cell differentiation and acquisition of effector functions through a STAT4-dependent mechanism. Here, we show that IL-21 does not require STAT4 to stimulate development of cytolytic activity. Furthermore, IL-21 fails to induce IFN-γ or IL-4 production and can partially block IL-12 induction of IFN-γ production. CD8 T cells that differentiate in response to IL-21 have a distinct surface marker expression pattern and are characterized as CD44 high, PD-1low, CD25low, CD134low, and CD137low. Thus, IL-21 can provide a signal required by naive CD8 T cells to differentiate in response to Ag and costimulation, and the resulting effector cells represent a unique effector phenotype with highly effective cytolytic activity, but deficient capacity to secrete IFN-γ.
AB - IL-21, the most recently described member of the common γ-chain cytokine family, is produced by activated CD4 T cells, whereas CD8 T cells express the IL-21 receptor. To investigate a possible role for IL-21 in the priming of naive CD8 T cells, we examined responses of highly purified naive OT-I CD8 T cells to artificial APCs displaying Ag and B7-1 on their surface. We found that IL-21 enhanced OT-I clonal expansion and supported development of cytotoxic effector function. High levels of IL-2 did not support development of effector functions, but IL-2 was required for optimal responses in the presence of IL-21. IL-12 and IFN-α have previously been shown to support naive CD8 T cell differentiation and acquisition of effector functions through a STAT4-dependent mechanism. Here, we show that IL-21 does not require STAT4 to stimulate development of cytolytic activity. Furthermore, IL-21 fails to induce IFN-γ or IL-4 production and can partially block IL-12 induction of IFN-γ production. CD8 T cells that differentiate in response to IL-21 have a distinct surface marker expression pattern and are characterized as CD44 high, PD-1low, CD25low, CD134low, and CD137low. Thus, IL-21 can provide a signal required by naive CD8 T cells to differentiate in response to Ag and costimulation, and the resulting effector cells represent a unique effector phenotype with highly effective cytolytic activity, but deficient capacity to secrete IFN-γ.
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U2 - 10.4049/jimmunol.178.12.7640
DO - 10.4049/jimmunol.178.12.7640
M3 - Article
C2 - 17548600
AN - SCOPUS:34250173393
SN - 0022-1767
VL - 178
SP - 7640
EP - 7648
JO - Journal of Immunology
JF - Journal of Immunology
IS - 12
ER -