Association of high serum concentration of the third component of complement (C3) with pre-existing severe coronary artery disease and new vascular events in women.

Atherosclerosis is an inflammatory disease. The complement system plays an important role in the atherosclerotic process. However, lesser data is available on the possible role of C3 as a risk factor for atherosclerosis. Therefore, in a follow up study we determined C3 levels in 266 patients with pre-existing severe coronary artery disease (CAD) and compared their serum C3 concentrations with the cause of the disease. We investigated whether C3 levels predict the major complications of severe CAD during a 5-year long follow up period in patients, who have received an aorto-coronary bypass graft surgery. C3 concentrations were elevated in the patients with severe CAD compared to 182 healthy controls, and women had higher C3 concentrations than men. Pathological C3 levels (C3> or =1.8 g/L) were able to predict major complications of atherosclerosis (death by cardiac events, new acute myocardial infarction, stroke, carotid surgery and peripheral arterial disease) that developed during the follow up period only in women (OR: 4.1, 95% C.I. 1.23-13.61, p = 0.0249) independent of other risk factors for atherosclerosis. Our data supports the assumption that high C3 indicates the progression of atherosclerosis as a special marker of chronic inflammation.

An age-associated decrease in the frequency of C4B*Q0 indicates that null alleles of complement may affect health or survival.

We studied the distribution of complement C4, C3, and factor B allotypes in 423 healthy Icelandic subjects from 17 to 89 years of age. A marked decrease was observed in the carrier frequency of variant alleles of complement C4B (C4B(*)Q0) and C3 (C3(*)F). These results confirm our previous observations on Hungarian subjects and suggest a negative effect of C4B(*)Q0 on health or survival.