Low levels of IgG autoantibodies against the apolipoprotein B antigen p210 increases the risk of cardiovascular death after carotid endarterectomy.

OBJECTIVES: Autoimmune responses against oxidized-LDL (oxLDL) have been suggested to modulate inflammation in atherosclerosis. Previous studies showed an association between autoantibodies against the apolipoprotein B (apoB) p210 antigen and a lower risk of cardiovascular (CV) events. In the present study we investigated if autoantibodies against p210 at the time of carotid endarterectomy (CEA) predict risk for future CV events.

METHODS: Native (nat) and malondialdehyde (MDA)-modified apoB p210 autoantibodies (IgM-p210nat, IgG-p210nat, IgM-p210MDA and IgG-p210MDA) were analyzed by ELISA from plasma samples of 351 patients at the time they underwent CEA. The incidence of postoperative CV events was assessed using national registers.

RESULTS: A total of 52 non-fatal and 15 fatal CV events were registered during the follow-up period (35.1 ± 16.7 months). Patients who suffered from a fatal CV event had significantly lower plasma levels of IgG-p210nat and IgG-p210MDA. Kaplan-Meier curves of event-free survival showed increased CV mortality in patients with levels of IgG-p210nat and IgG-p210MDA below the median (Log Rank 7.813, p .005 and 9.105, p .003 respectively). The association between low levels of p210 IgG and fatal post-operative CV events remained significant when adjusting for age, sex, total cholesterol, HDL cholesterol, smoking habits and hypertension in a Cox Proportional Hazard model (hazard ratios (HR) IgG-p210nat below median: HR 6.7 (95% C.I. 1.5-30.6, p .013) and IgG-p210MDA below median: HR 7.8 (95% C.I. 1.7-35.5, p .008).

CONCLUSIONS: The present findings support the notion that autoantibodies against LDL antigens are involved in the atherosclerotic disease process and suggest that CEA patients with low levels of IgG-p210nat and IgG-p210MDA have an increased risk of post-operative CV death.