Is our immune system also a matter of time?

Time of day affects the immune system's immune system
Our defenses are influenced by a variety of factors. Here our biorhythm seems to play a bigger role than previously thought. Researchers at the Ludwig-Maximillians-Universität (LMU) Munich found in a recent study that the lymphocytes, which have a significant influence on the immune system, circulate through the body in a certain rhythm. So the immune response fluctuates during the day.

Depending on the time of day, the lymphocytes "stimulate the immune response stronger, sometimes weaker," reports the LMU. This is due to the fact that they circulate throughout the body in a so-called circadian rhythm of about 24 hours. The results of the current study may also have influence on the administration of vaccines, the researchers report. It may be that in the future the time of day of a vaccine will be adapted specifically to the circadian rhythm of the immune response.

The immune system is subject to significant fluctuations over the course of the day due to circulating lymphocytes. (Image: ag visual / fotolia.com)

Adaptive immune response at certain times much stronger
According to the researchers, the lymphocytes play an important role in the defense against pathogens such as bacteria and viruses. The analysis of the migration of lymphocytes through the body throughout the day makes it clear that very different immune reactions at different times of the day are to be expected here. How the LMU Physiologists Dr. Christoph Scheiermann and David Druzd report in the current issue of the journal "Immunity" that the adaptive immune response is significantly stronger at certain times.

In the daytime in the blood, at night in the lymph nodes
Using the mouse model as an example, the researchers were able to demonstrate in the current study that the time of day determines where the lymphocytes are in the body. This has lasting effects on the immune response. "During the day, the lymphocytes circulate strongly in the blood, at night they collect in lymph nodes." Scheiermann. This rhythm of the lymphocyte distribution has far-reaching effect, according to the physicians. That also applies to vaccinations. "The time of day immunization has a lasting effect on the immune response," continued Scheiermann. Depending on the time, the immune response turned out to be very different. (Fp)