Antibodies against oxidized LDL - Theory and clinical use

Modification of low density lipoprotein (LDL) particles due to oxidation, g lycation and binding of advanced glycation end-products (AGEs) or malondial dehyde (MDA, a final product of lipid peroxidation) is considered most impo rtant in the process of atherogenesis. Oxidatively modified LDL, are distin guished by another receptor type, which was discovered on the surface of ma crophages and was called the scavenger receptor. Uncontrolled intake of LDL converts macrophages to foam cells; their accumulation under the vascular endothelium is considered as the first stage of atherosclerosis. Oxidation of LDL is a complex process taking place in both the extra- and intracellul ar space. At the end of this oxidative process, modified LDL particles show chemotactic, cytotoxic and immunogenic properties. Oxidized LDL express a large number of epitopes and cause production of polyclonal autoantibodies against these products, especially against apoB(100) modified by MDA and 4- hydroxynonenal. IgoxLDL (antibodies against oxidized LDL) can be demonstrat ed either directly in intimal lesions or as a component of circulating immu ne complexes. IgoxLDL do not form a homogeneous group but a varied mixture of antibodies-isoantibodies caused by HDL and LDL polymorphism, antibodies against the lipid phase of LDL and antibodies against modified apoB(100) of the immunoglobulin class IgA or IgG. Antibodies against oxLDL were found i n many diseases other than atherosclerosis such as diabetes mellitus, renov ascular syndrome, uremia, rheumatic fever, morbus Bechtjerev or lupus eryth ematodes. Newborns have practically the same levels of IgoxLDL as their mot hers; however, these values did not differ From those in the healthy popula tion of non-pregnant women of the same age. The decrease in IgoxLDL titer w as very slow and lasted many months; that is why this parameter cannot be c onsidered suitable for describing the rapid changes during oxidative stress of the organism. positive correlation of IgoxLDL with antiphospholipids an d other antibodies was repeatedly demonstrated; their determination can thu s be used as a marker for the description of total production of autoantibo dies in various diseases. The changes and correlations of IgoxLDL, anti-bet a -2-glycoprotein I IgG and antiphospholipid antibodies support the immunol ogical link between thrombotic and atherosclerotic processes in the human b ody.