Analyzing the Relationship between in Vivo Oxidized Low Density Lipoprotein and Low Density Lipoprotein Immune Complexes

Aim To investigate the possible relationship between oxidized low density lipoprotein (ox-LDL) and LDL-immune complexes (IC) level. Methods We developed a ELISA for measuring plasma LDL-IC level using anti-human IgG (Fab) as the capture antibody and quantitating with monoclonalanti-apoB enzyme conjugate. Oxidixed LDL was also detected by a sandwich ELISA method using monoclonal antibodies against ox-LDL as the capture antibody and quantitating with anti-apoB enzyme conjugate. Their levels were studied in 60 patients with coronary heart disease (CHD) and 50 control subjects. Results Plasma concentrations of TG, lipoprotein (a) and apolipoprotein B in CHD patients were all significantly increased whereas HDLC and apolipoprotein AI levels were decreased. Plasma LDL-IC (2.74 ± 0.73 AU vs 1.38 ± 0.78 AU, P 0.001) and ox-LDL (595.5 ±194.8 μg/L vs 440.3 ± 175.0 μg/L, P0.001) concentrations in the patients with CHD were both significantly higher than those of control. The relationships between LDL-IC ox-LDL levels and other lipid traits in all the studied subjects ( n = 110) were carried out. LDL-IC levels were positively correlated with TC, TG, LDLC, lipoprotein(a) and apolipoprotein B concentrations while negatively correlated with apolipoprotein AI concentrations respectively. Similarly ox-LDL levels were also found positively correlated with TC, LDLC, or apolipoprotein B concentrations respectively. Furthermore a significantly positive relation between ox-LDL and LDL-IC levels was found (r = 0.313, P 0.005). Conclusions Increased oxidized LDL and LDL immune complexes levels are risk factors for atherosclerosis.