Findings from a population-based study in northern Sweden suggest that the risk of stroke may be linked to a certain type of antibody in the immune system.
Low levels of natural immunoglobulin M (IgM) antibodies specific for phosphorylcholine (anti-PC) have been identified as a novel independent risk marker for development of stroke. Results of a population-based study from northern Sweden, published online ahead of print February 11 by Stroke, suggest that measurements of IgM anti-PC could be used to identify immunodeficient subjects at increased risk for stroke.
Using a nested case control study design, researchers from Karolinska Institutet in Stockholm examined the role of IgM anti-PC in incident stroke. They examined 227 cases (125 men; mean age at inclusion, 55) of first-time stroke and 455 age- and sex-matched controls, all drawn from larger population-based studies in northern Sweden. Odds ratios of stroke adjusted for age, sex, smoking, serum cholesterol, diabetes, BMI, and blood pressure were determined. IgM anti-PC levels were measured with ELISA.
A significant association between low levels of IgM anti-PC and incident stroke was seen for the entire group of anti-PC levels below the 30th percentile. Sex-specific subanalyses indicated fairly strong associations for women, especially at the lowest 30th percentile. No associations were noted for men.
The present data confirm and extend the researchers’ earlier findings. In previous reports, they had shown that high levels of IgM anti-PC predict a slower progression of atherosclerosis and that low levels were associated with higher risk for cardiovascular disease.
The researchers speculate that the mechanism by which IgM anti-PC could protect against stroke could be related to the anti-inflammatory properties of anti-PC previously demonstrated by the group, inhibiting the inflammatory effects of PC-containing inflammatory phospholipids, including platelet-activating factor. “Because proinflammatory cytokines in plaques are abundantly produced by immune competent cells, especially close to sites prone to plaque rupture, anti-PC could in principle protect from cardiovascular disease and stroke by this anti-inflammatory effect,” the researchers wrote. They further suggested that their findings may pave the way for “novel immunotherapy regimens against atherosclerosis and stroke or other forms of cardiovascular disease either through passive transfer of anti-PC antibodies or active immunization using PC as an antigen.”
—Glenn S. Williams