Antibodies against modified low-density lipoproteins and their complexes in blood of patients with various manifestations of atherosclerosis

The study included 79 patients with coronary artery disease (CAD), 25 individuals with preclinical atherosclerosis and 59 healthy individuals. Key lipid parameters were examined in all the participants. Levels of antibodies (Abs) (IgG and IgM) against low density lipoproteins (LDL) modified by malondialdehyde (MDA), acetic anhydride and hypochlorite, were determined by the enzyme-linked immunosorbent assay (ELISA). Abs specificity was tested by competitive ELISA. Circulating immune complexes (CIC) were isolated by polyethylene glycol precipitation followed by determination of their cholesterol by the enzymatic method. Abs to hypochlorite-modified LDL (hypochlorite-LDL) detected in the serum samples did not demonstrate cross-reactivity with MDA-modified LDL (MDA-LDL) and acetylated LDL (acetyl-LDL). Patients with CAD had increased levels of CIC ( p < 0.0001) and decreased levels of Abs (IgM) to hypochlorite- LDL, compared with healthy controls and patients with preclinical atherosclerosis ( p = 0.006). A correlation between the levels of Abs (IgG) to the hypochlorite-LDL and Abs to MDA-LDL and acetyl-LDL was found. The content of the Abs (IgM) to MDA-LDL and acetyl-LDL correlated with CIC-cholesterol concentrations, while lipid parameters did not correlate with Abs levels.