Cortisol and epinephrine control opposing circadian rhythms in T cell subsets

S Dimitrov, C Benedict, D Heutling… - Blood, the Journal of …, 2009 - ashpublications.org
S Dimitrov, C Benedict, D Heutling, J Westermann, J Born, T Lange
Blood, the Journal of the American Society of Hematology, 2009ashpublications.org
Pronounced circadian rhythms in numbers of circulating T cells reflect a systemic control of
adaptive immunity whose mechanisms are obscure. Here, we show that circadian variations
in T cell subpopulations in human blood are differentially regulated via release of cortisol
and catecholamines. Within the CD4+ and CD8+ T cell subsets, naive cells show
pronounced circadian rhythms with a daytime nadir, whereas (terminally differentiated)
effector CD8+ T cell counts peak during daytime. Naive T cells were negatively correlated …
Abstract
Pronounced circadian rhythms in numbers of circulating T cells reflect a systemic control of adaptive immunity whose mechanisms are obscure. Here, we show that circadian variations in T cell subpopulations in human blood are differentially regulated via release of cortisol and catecholamines. Within the CD4+ and CD8+ T cell subsets, naive cells show pronounced circadian rhythms with a daytime nadir, whereas (terminally differentiated) effector CD8+ T cell counts peak during daytime. Naive T cells were negatively correlated with cortisol rhythms, decreased after low-dose cortisol infusion, and showed highest expression of CXCR4, which was up-regulated by cortisol. Effector CD8+ T cells were positively correlated with epinephrine rhythms, increased after low-dose epinephrine infusion, and showed highest expression of β-adrenergic and fractalkine receptors (CX3CR1). Daytime increases in cortisol via CXCR4 probably act to redistribute naive T cells to bone marrow, whereas daytime increases in catecholamines via β-adrenoceptors and, possibly, a suppression of fractalkine signaling promote mobilization of effector CD8+ T cells from the marginal pool. Thus, activation of the major stress hormones during daytime favor immediate effector defense but diminish capabilities for initiating adaptive immune responses.
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