Antibodies of IgM subclass to phosphorylcholine and oxidized LDL are protective factors for atherosclerosis in patients with hypertension.

OBJECTIVE

To determine the importance of antibodies against phosphorylcholine (PC) and oxidized low density lipoprotein (OxLDL) for development of atherosclerosis.

METHODS AND RESULTS

Two hundred and twenty six individuals with established hypertension (diastolic pressure > 95mmHg) were from European Lacidipine Study on Atherosclerosis. Antibodies of IgG and IgM subclass were tested by ELISA against PC (aPC), cupper-oxidized (ox)- or malondialdehyde (MDA)-modified LDL. High-sensitivity C-reactive protein was measured by nephelometry. As a surrogate measure of atherosclerosis, we used the mean of the maximum intima-media thicknesses (IMT) in the far walls of common carotids and bifurcations was determined by ultrasonography at the time of enrolment, and 4 years following enrolment. aPC could be competed out by PC and OxLDL, while cardiolipin (CL) and beta2-glycoprotein I (beta2GPI) were less effective and phosphatidylserine (PS) not at all. Increases in IMT at follow-up were less common in subjects which at the time of enrolment had high IgM aPC (both 75th and 90th; odds ratios: 0.46; CI: 0.25-0.85; 0.36; CI: 0.15-0.87) and high IgM aOxLDL and aMDA-LDL (90th; odds ratios 0.27; p = 0.01; CI: 0.11-0.69 and 0.27; p = 0.01; CI: 0.11-0.69). CRP was unrelated to IMT-changes. The relationship between IgM aPC, aOxLDL and aMDA-LDL and changes in IMT was independent of age, treatment with atenolol or lacidipine, smoking and lipids. Women had higher levels of IgM antibodies tested (p < 0.05).

CONCLUSIONS

High levels of IgM-antibodies against PC and OxLDL predict a favourable outcome in the development of carotid atherosclerosis in hypertensive subjects. Whether these antibodies could be used therapeutically deserves further study.