°at present Department of Vascular Surgery, St. Görans Hospital, Stockholm,
Sweden
We have cloned a
murine autoantibody E06 which recognizes OxLDL and specifically recognizes
oxidized phospholipids such as POVPC
(1-palmitoyl-2-(5-oxovaleroyl)-3-sn-phosphorylcholine). We developed a sandwich
assay to measure the content of the E06 epitope on human LDL utilizing a
monoclonal antibody to apoB to capture LDL from plasma and biotinylated E06 to
detect the content of the OxPL epitope present on the captured LDL. When
performing this test on a population of patients with premature peripheral
vascular disease we surprisingly found a high correlation between Lp(a) levels
and E06 levels (r=0.84 p<0.0000). This was true in both the patients (r=0.90
p< 0.0000) and control populations (r=0.78 p< 0.0000). We have subsequently confirmed this
strong association in three separate population studies. On Western blots Lp(a)
does not immunostain with E06, suggesting that the antibody is not binding to
intrinsic epitopes of (a). In summary, these data suggest that elevated Lp(a)
levels are associated with an increased content of oxidized phospholipid
epitopes on plasma LDL. It will be of interest to determine if this relates to
the increased risk associated with high Lp(a) levels.