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.