Unlike the innate immune system, the acquired immune system targets a specific pathogen. To do this, dendritic cells migrate to the lymph nodes, where they inform the body’s own defenses about the intruder. This process depends on the time of day and follows a 24-hour cycle, as reported by a research team from the University of Geneva and the Ludwig Maximilians University in Munich in the journal Nature Immunology.
According to this, the activation of the immune system is most pronounced in the late resting phase, in nocturnal mice in the afternoon and in humans in the early morning, as the researchers found in animal experiments and in experiments with human cell cultures.
“We have identified numerous molecules, especially chemokines, that are involved in the migration process and whose expression is regulated by the internal clock,” said the head of the study, Christoph Scheiermann from the University of Geneva, according to a statement from the university on Monday. Chemokines are cellular messenger substances that play a central role in the immune system.
The researchers are not yet able to conclusively answer whether this daily rhythm keeps the immune system on alert when the risk of infection increases.
A British research team found evidence in an earlier study that the severity of a viral infection depends on the time of day. According to this, herpes and influenza viruses multiplied ten times faster in nocturnal rodents if they were infected at the beginning of their resting phase. A disruption of the internal clock leads to increased virus replication and spread, the researchers wrote.
Scheiermann’s team will now try to record the immune response that occurs when a pathogen or vaccine enters the body. Because the timing of the administration of vaccines or immunotherapies could possibly actually influence their effectiveness, according to the University of Geneva.
https://www.nature.com/articles/s41590-021-01040-x