Auckland: Human immune function is more effective during the day, thanks to a built-in cellular clock that responds to light, according to new research from the University of Auckland. The study reveals that neutrophils, the most abundant type of white blood cells, are guided by an internal circadian clock that enhances their ability to fight infections during daylight hours, said a press release from the university.
According to Namibia Press Agency, neutrophils are the immune system’s first responders, and they become more efficient in the daytime, said University of Auckland Associate Professor Christopher Hall, who led the research. “We think this represents an evolutionary response such that during daylight hours the host is more active, so more likely to encounter bacterial infections,” Hall said.
The research team used zebrafish, a small freshwater fish, as a model organism, given their genetic similarities to humans and their transparent bodies, which allow scientists to observe immune cell behavior in real time. The findings, published in Science Immunology, build on earlier evidence linking disruptions to circadian rhythms, such as those caused by shift work or jet lag. By identifying the clock mechanism inside neutrophils, the study sheds light on how the immune system aligns with the daily light-dark cycle.
“Given that neutrophils are the first immune cells to be recruited to sites of inflammation, our discovery has very broad implications for therapeutic benefit in many inflammatory diseases,” Hall said, adding it opens the door to therapies that enhance immune function by targeting the circadian clock in neutrophils to boost their ability to fight infections. Ongoing studies are now exploring how light signals influence these immune cell clocks at the molecular level, the researchers said.