Acute sleep deprivation in healthy young men: Impact on population diversity and function of circulating neutrophils

Lack of sleep greatly affects our immune system. The present study investigates the acute effects of total sleep deprivation on blood neutrophils, the most abundant immune cell in our circulation and the first cell type recruited to sites of infection. Thus, the population diversity and function of circulating neutrophils were compared in healthy young men following one night of total sleep deprivation (TSD) or after 8 h regular sleep. We found that neutrophil counts were elevated after nocturnal wakefulness (2.0 ± 0.2 × 109/l vs. 2.6 ± 0.2 × 109/l, sleep vs. TSD, respectively) and the population contained more immature CD16dim/CD62Lbright cells (0.11 ± 0.040 × 109/l [5.5 ± 1.1%] vs. 0.26 ± 0.020 × 109/l [9.9 ± 1.4%]). As the rise in numbers of circulating mature CD16bright/CD62Lbright neutrophils was less pronounced, the fraction of this subpopulation showed a significant decrease (1.8 ± 0.15 × 109/l [88 ± 1.8%] vs. 2.1 ± 0.12 × 109/l [82 ± 2.8%]). The surface expression of receptors regulating mobilization of neutrophils from bone marrow was decreased (CXCR4 and CD49d on immature neutrophils; CXCR2 on mature neutrophils). The receptor CXCR2 is also involved in the production of reactive oxygen species (ROS), and in line with this, total neutrophils produced less ROS. In addition, following sleep loss, circulating neutrophils exhibited enhanced surface levels of CD11b, which indicates enhanced granular fusion and concomitant protein translocation to the membrane. Our findings demonstrate that sleep loss exerts significant effects on population diversity and function of circulating neutrophils in healthy men. To which extent these changes could explain as to why people with poor sleep patterns are more susceptible to infections warrants further investigation.