There are two “oxidized LDL” assay that have appeared in publications that are not based on the 4E6 antibody. One was developed by Hirouki Itabe, Showa University School of Pharaceutical Sciences, Tokyo, Japan. The Itabe assay is based on monoclonal antibody DLH3. The antibody is directed against epitopes of oxidated phosphatidylcholines. Itabe et al clearly states that the DLHS antibody assay is not suitable for mass screening since “it takes several hours to separate the LDL fraction using ultracentifugation” and that following centrifugation, “the resulting LDL fraction requires dialysis.” (1) Irrespective of specimen stability and preparation requirements, the major drawback is that the assay cannot identify patients with chronic, stable coronary artery disease from patients without CAD.
The second test was developed by the Witztum Laboratory, University of California San Diego, CA. The Witztum assay is based on the monoclonal antibody E06. The antibody is directed against epitopes of oxidated phospholipids. Tsimikas et al (2) showed that there was a very strong correlation (r = 0.91, p<0.0001) between oxidized LDL levels based on the E06 antibody and plasma lipoprotein a (Lp a), which is an acute phase reactant. It is noteworthy that oxidized LDL using Holvoet’s 4E6 antibody has a weak correlation (r = 0.010). Most important, Tsimikas et al were unable to demonstrate increased levels for patients with chronic, stable coronary artery disease from patients without CAD.
The ability to identify patients with both chronic and acute CAD using the Holvoet 4E6 oxLDL antibody is a clear and significant advantage enabling treatment before serious damage has taken place. The comparison data presented in the following poster presentation shows that the oxidized LDL:HDL Ratio test based on 4E6 antibody developed Professor Paul Holvoet identified 49% more obstructive CAD patients than the oxidized phospholipids:Apo B Ratio test based on the E06 antibody.
(1) Itabe et al J Atheroscler Thromb, 2007; 14:1-11
(2) Tsimikas et al N Engl J Med 2005;353:46-57