Autoantibodies against oxidized low density lipoproteins in patients with stable angina, unstable angina or peripheral vascular disease: Pathophysiological implications

Background: Antibody antioxidized low density lipoproteins (oxLDL) might play a role both in atherogenesis and in the pathogenesis of acute coronary syndromes. Methods and Results: Antibody titres to oxLDL and levels of C-reactive protein were compared in unstable angina, stable angina or peripheral artery disease. Antibody titres to LDL oxidated by CuSO₄ for 2, 4 and 18 h (Cu-oxLDL-Ab_2-4-18) or by peroxidase (HRP-oxLDL-Ab) were assessed by ELISA. Cu-oxLDL-Ab_2-4-18 were consistently higher in peripheral artery disease than in unstable angina (P<0.001, P<0.001, P=0.01, respectively) or in stable angina (P<0.001, P=0.01, P=ns) but similar in unstable and stable angina. Accordingly, HRP-oxLDL-Ab were higher in peripheral artery disease than in unstable angina (P<0.001) or stable angina (P=0.04) but similar in unstable and stable angina. The number of arterial stenoses was higher in peripheral artery disease than unstable and stable angina (P<0.01). Cu-oxLDL-Ab and HRP-oxLDL-Ab correlated with the severity of atherosclerosis (P<0.01, R=0.4; P=0.02, R=0.3 respectively). Conversely, C-reactive protein levels were higher in unstable than in stable angina (P<0.001) or in peripheral artery disease (P<0.03) but similar in stable angina and peripheral artery disease and did not correlate with the severity of atherosclerosis. Conclusion: The autoimmune response to oxLDL is likely to play an important role in atherogenesis but not in precipitating acute coronary syndromes.