Daylight activates immunity

Sometimes the simplest things turn out to be incredibly important. Ordinary sunlight is one of them. New Zealand researchers have found that it can boost the immune system, helping the body fight infections faster and more effectively.

The focus was on neutrophils, a special type of white blood cells. These cells are the first to arrive at the site of inflammation and instantly start destroying foreign microorganisms.

To understand exactly how light affects the behaviour of neutrophils, the team from the University of Auckland conducted observations on danio- rerio – a small transparent fish, genetically similar to humans. Thanks to its translucent body, the scientists were able to monitor cells in real time.

According to one of the authors of the study, Christopher Hall, in previous experiments it was noticed that immune activity peaks in the morning – exactly at the time when the body begins to wake up. The scientists then speculated that this might be part of an evolutionary strategy: during the day, humans are more likely to come into contact with the environment and, consequently, with bacteria.

The new work confirmed the hunch: neutrophils do indeed ‘see’ day and night. They have their own internal clock that synchronises with daylight and enhances the cells’ ability to destroy bacteria.

This discovery could prove crucial for the therapy of inflammatory diseases. If we can learn how to control this biological clock, it may be possible to improve the effectiveness of treatments and speed up recovery from infections.

Currently, the research team is focused on understanding the exact mechanism – how exactly light adjusts the rhythm of neutrophils. This will help in the future to create drugs that ‘wake up’ the immune system when it is needed most.

Understanding the role of light in the regulation of immune processes may change the approach to the treatment of a number of diseases. And perhaps in the future doctors will not only prescribe pills, but also recommend more walks in the sun – as a simple and safe support for the immune system.