Lange, T. et al. (2011). Sleep after vaccination boosts immunological memory. The Journal of Immunology. 187: 283-90. [PubMedID:21632713]
The role of sleep in forming memories of the previous day’s events appears to be relevant not only to the brain, but also to the immune system. Research conducted in a variety of labs over the last decade has shown how sleep is essential for immunity.
For example, we are more susceptible to infections when sleep-deprived (reviewed in Nature Reviews Immunology).
Tanja Lange and her co-workers in Lübeck turned this idea around, to investigate how sleep could be used to improve an immune response. They used a cohort of 27 healthy volunteers with no previous history of Hepatitis A or B, and gave them a course of 3 immunizations against Hepatitis A virus (HAV). Subjects were vaccinated in the morning at 8am, and after each immunization, half of the study participants were allowed a normal night’s rest, while half were kept awake until 8pm the following day.
The next step was to monitor the responses to vaccination. The team used a thinkpeptides® PEPscreen® library designed to include overlapping peptides from four HAV viral proteins, to enable them to measure an antigen-specific T cell response in blood samples taken from the immunized study volunteers. Peripheral blood mononuclear cells were isolated from the samples and stimulated with the HAV peptide library for 6 hours, before staining with T cell markers. Across the study, the sleeping volunteers had a doubling of the number of HAV-specific helper T cells with an activated (CD40L+) phenotype. This increase was apparent from 2 weeks after the first immunization and continued for up to a year (the end of the study).
Intracellular staining for cytokines showed that there was also a significant increase in the proportion of the activated HAV-specific helper T cells producing cytokines including IFNɣ and IL-2, associated with the Th1 response generated by successful vaccination. Increases in the levels of anti-HAV IgG1 antibodies were also noted over the course of the study, and these increases were greatest in the ‘sleep’ cohort as compared to the ‘wake’ cohort.
When the type of sleep experienced by the ‘sleep’ cohort was analyzed in more detail, the length of time spent in slow wave sleep (which allowed for production of hormones such as prolactin) correlated most strongly with an increased helper T cell response.
This research could pave the way for new vaccination strategies, in which patients are immunized at particular times of day, and when they can be sure of getting a good night’s sleep. Stronger responses could be elicited consistently from existing vaccines by simply using sleep to make them more effective.
This work was performed at the University of Lübeck, Germany.