Mannose-binding lectin as a risk factor for acute coronary syndromes.

Background: Mannose-binding lectin (MBL) is a multifunctional protein involved in innate immunity. We tested whether MBL and elevated viral and bacterial antibodies were risk factors for acute coronary events.

Design: Controlled cohort study.

Methods: A total of 354 patients with unstable angina pectoris (UA) or acute myocardial infarction (AMI) were compared with 334 paired controls.

Results: Enterovirus titres were associated with increased risk of UA (odds ratio 10.04, P<0.001) and AMI (odds ratio 3.18, P=0.003), but titres did not correlate with either MBL concentration or genotype. Chlamydia pneumoniae heat shock protein 60 IgG concentrations were also associated with increased risk of UA (odds ratio 1.63, P=0.049). Compared to asymptomatic controls, patients had lower complement C3 serum concentrations (P<0.001), higher MBL serum concentration, and more frequently had MBL genotypes that determined high MBL levels (P<0.001). High MBL genotypes had odds ratios of 1.16 (P=0.010) for UA and 1.12 (P=0.007) for AMI. The elevation of MBL concentrations in the acute phase correlated with MBL concentrations after recovery (r=0.85, P<0.001).

Conclusions: Elevated microbial titres, indicating an on-going inflammation, were associated with cardiovascular events. MBL might have a dual role both decreasing susceptibility to infections and increasing the risk of acute coronary syndromes.