Irish scientists have shed significant new light on the role played by the immune system in obesity.

In a research finding that could pave the way for new treatments for the condition, a team led by Prof Donal O’Shea of St Vincent’s hospital in Dublin has found that obesity has a major impact on specialised immune cells that line the gastrointestinal tract.

These cells, known as Mait cells, are differently affected by obesity in children compared to obesity in adults; this is the first time such a difference has been observed.

The research, to be published shortly in the Journal of Immunology, emerged from a study of patients attending the weight-management clinic in the hospital. It was found the number of a particular immune cell was low in the blood and fat of obese patients.

French researchers have simultaneously shown the cells increase in number after weight loss induced by gastric bypass surgery.

Prof O’Shea described the research as a significant step forward. “If we can understand how the body burns energy and defends itself against weight loss, we’ll eventually be able to come up with different treatments.”

He stressed the need to come up with new treatments as the strategy of preventing obesity didn’t always work.

“The message is still that you have to keep the body physically active and eat healthily. But something happens when you put on weight that promotes further weight gain and makes it harder to lose weight,” said Prof O’Shea.

He warned that while new immunotherapies may eventually be delivered, they could prove extremely costly.