A.A. Ivantsova - Laboratory Assistant, Department of Biochemistry, Federal State Budgetary Scientific Institution «Institute of Experimental Medicine», Saint-Petersburg, Russia. E-mail: anna.ivantcova@gmail.com I.V. Belik - Laboratory Assistant, Department of Biochemistry, Federal State Budgetary Scientific Institution «Institute of Experimental Medicine», Saint-Petersburg, Russia. E-mail: ivanbelik2014@ya.ru

Circulating antibodies (Abs) against various modifications of low-density lipoprotein (LDL) were detected in human blood. Among the immunogenic and pro-atherogenic modification of LDL the modification by hypochlorite - product of myeloperoxidase, an enzyme in-nate immunity, is interesting for us. To identify the presence of Abs against the hypochlorite-modified LDL (hypochlorite-LDL) in human serum. To prove the specificity of Abs against the hypochlorite-LDL. The study involved 163 people. Abs levels were assessed by enzyme-linked immunosorbent assay (ELISA). As the antigens, human serum albumin and human LDL modified by in vitro system HOCl/NaOCl, malondialdehyde and acetic anhydride. Antibody levels are expressed in relative units (results of native LDL wells were subtracted from results of the modified LDL). Specificity of Abs was tested by competitive ELISA, modified LDL, that mentioned above, were used as competitors. Abs to hypochlorite-LDL was detected in the serum samples. Reaction between these Abs and hypochlorite-LDL was inhibited only by self antigen (i.e., by hypochlorite-LDL), but not native, acetylated or MDA-modified LDL. These data suggest a high specificity of these antibodies. Using a modified human serum albumin instead of lipoproteins leads to similar results; so it can be used as a model protein. A modification of LDL by hypochlorite leads to the formation of epitopes other than products of acetylation and MDA-modification of lipoproteins. These epitopes are responsible for the formation of specific antibodies (IgG and IgM).

 

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