A New Zealand study has found that sunlight can enhance the human immune system

New research has found that the human immune function is more active and efficient during the day, which is attributed to a biological clock mechanism in which immune cells respond to light.

Xinhua News Agency reported that researchers from the University of Auckland in New Zealand recently published this research result in the US journal Science Immunology, further supporting the previous scientific view that circadian rhythm disorders (such as night shift work and jet lag) may increase the risk of infection.

New research shows that neutrophils, an important immune cell in the body, are controlled by a circadian rhythm and are more effective in responding to infections during the day. The research team stated that this is a manifestation of the coordination between the human immune system and the natural circadian changes, and it is an adaptive mechanism formed by humans during the process of evolution. Because humans are more active during the day and are more likely to be exposed to bacterial infections, the immune system is more alert during the day.

To deeply observe the activities of immune cells, researchers chose zebrafish as the experimental model. This freshwater fish has a high degree of genetic similarity to humans and its body surface is transparent, which is convenient for real-time tracking of cell behavior.

Researchers captured images of neutrophils killing bacteria at different times of the day and found that their efficiency in killing bacteria during the day was higher than that at night. Subsequently, the researchers turned off the biological clock of neutrophils through gene editing methods. It was found that these important immune cells have an internal circadian clock regulated by light, which can alert the cells to the arrival of the day like an alarm clock, thereby enhancing their ability to kill bacteria.

Researchers point out that neutrophils are the earliest "frontline warriors" mobilized by the immune system when inflammation occurs. The newly discovered biological clock mechanism not only helps to understand the operation mode of the immune system, but also provides new ideas for the treatment of various inflammatory diseases. Subsequently, they will conduct in-depth research on how light signals regulate the rhythms of these immune cells at the molecular level, with the aim of laying the foundation for the future development of new therapies to enhance immunity.