The level of complement C3 is associated with the severity of atherosclerosis but not with arterial calcification in peripheral artery disease.

Recent evidences show correlations between atherosclerosis and the serum level of third component of complement (C3). However, there is less data on the connection of C3 and the severity of atherosclerosis. The aim of our study was to evaluate the association of serum C3 levels with atherosclerosis and arterial calcification in patients with chronic lower extremity atherosclerosis. In a single centre cross-sectional study 103 patients and 109 healthy controls were examined. Sera were analyzed for C3. To identify the severity of atherosclerosis and calcification, ankle-brachial Doppler index, angiographic Bollinger score, arterial calcification score and carotid intima-media thickness was determined. Serum level of C3 was significantly higher in the lower extremity atherosclerosis group than in healthy patients (P=0.00004). In the patient group, serum level of C3, C4 was significantly and inversely associated with ABI (r=-0.246, P=0.014), (r=-0.259, P=0.011). C3 inversely correlates with Bollinger score (r= -0.357, P=0.028). Among our patients no correlation was found between C3 levels and CS (P=0.672, r=-0.046) or between C3 levels and carotid IMT (r=0.104, P=0.351). The serum levels of different complement components were associated with C-reactive protein, Hba1c, peptide-C and insulin. Our results suggest that C3 serum levels are associated with ABI and angiographic parameters of atherosclerosis, but do not relate to the severity of calcification.