People with the highest number of antibodies had a 58 per cent lower risk of coronary heart disease or heart attack and a 38 per cent lower chance of suffering a stroke or other heart events during a five-year trial.
The team at Imperial College London and University College London studied more than 1700 people at risk of heart problems. Those with the lowest levels of antibodies had the highest risk of attack.
"Linking a stronger, more robust immune system to protection from heart attacks is a really exciting finding," said Dr Ramzi Khamis, lead researcher and consultant cardiologist at the National Heart and Lung Institute.
"As well as improving the way we tell who is at the highest risk of a heart attack so that we can give them appropriate treatments, we now have a new avenue to follow in future work.
"We hope that we can use this new finding to study the factors that lead some people to have an immune system that helps protect from heart attacks, while others don't.
"We also hope to explore ways of strengthening the immune system to aid in protecting from heart disease."
Measuring IgG, which is found in all bodily fluids, is simple and cheap. IgG antibodies protect against bacterial and viral infections.Researchers say the study focused on patients being treated for high blood pressure, and they now need to know whether the link also applies to other groups.