Overall, T and B cells exhibit strong circadian oscillations in the blood which are linked with oscillations in CXCR4 and CX3CR1 expression, regulated by glucocorticoids and catecholamines as well as hypoxia-inducible factor 1α signaling 44, which in turn contribute to development and severity of stroke, recovery from stroke, and neuronal protection after brain injury 44,53. Here, CXCR4 is linked to stroke disorder.