Researchers at the National Heart and Lung Institute at Imperial College London recently showed that high amounts of IgG and IgM antibodies in the blood may protect patients from experiencing heart attacks and other adverse cardiovascular events. The study, “High Serum Immunoglobulin G and M Levels Predict Freedom From Adverse Cardiovascular Events in Hypertension: A Nested Case-Control Substudy of the Anglo-Scadinavian Cardiac Outcomes Trial,” was published in the journal EBioMedicine.
Serum immunoglobulins (Ig) are often assessed in clinical practice because they provide useful information about the status of the immune system. IgG, the most common immunoglobulin, helps protect our bodies against bacteria and viral infections.
Studies have pointed toward an association between IgG and IgM levels in atherosclerosis and myocardial infarction. The research team, led by Dr. Ramzi Khamis, consultant cardiologist and Independent Clinical Research Fellow at the United Kingdom’s National Heart and Lung Institute, explored whether IgG and IgM levels could help determine cardiovascular risk in hypertensive patients.
Investigators examined hypertensive patients who participated in the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT). Among them, 485 patients who had cardiovascular events over the median 5.5 year followup were compared with 1,367 age and gender-matched controls. The researchers measured serum levels of IgG and IgM, as well as the levels of antibodies against an oxidized form of LDL — the bad cholesterol — called oxLDL, which is known to promote atherosclerosis, one of the leading causes of heart attack.
The results showed that the total serum IgG, and to a lesser extent IgM, were strongly associated with protection from heart attacks. Patients with high levels of IgG showed a 20 percent lower chance of having a heart attack than those with low levels of IgG, while high levels of IgM decreased the odds of heart attack by 17 percent. Antibodies against oxLDL also offered protection, but the effect was weaker than that of total IgG or IgM.
“Linking a stronger, more robust immune system to protection from heart attacks is a really exciting finding,” Khamis said. “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.”
Prof. Jeremy Pearson, associate medical director at the British Heart Foundation, which helped fund the research, said whether measurement of IgG will become a valuable tool for improving the prediction of heart attacks needs more investigation.
“But this well-designed study does provide further evidence for the role of the immune system in heart disease and the protective effects of IgG,” he said.