Baseline diene conjugation in LDL lipids as a direct measure of in vivo LDL oxidation.

OBJECTIVES

To additionally test validity of the recently developed method (LDL baseline diene conjugation, LDL-BDC) for determination of circulating oxidized LDL.

DESIGN AND METHODS

A detailed comparison between the ultracentrifugation and heparin precipitation methods for LDL isolation was performed to test suitability of the fast precipitation method. Validity of LDL-BDC as an indicator of circulating oxidized LDL was tested by comparing LDL-BDC to results obtained by the immunological autoantibody method.

RESULTS

BDC values in LDL isolated by heparin precipitation did not differ from those isolated by sequential ultracentrifugation. While highest amount of diene conjugation was found in LDL (40% of that in serum), substantial amounts were also found in VLDL (31%) and HDL (25%). When analyzed in the same samples, assays for the titer of autoantibodies against oxidized LDL and LDL-BDC were found to show good correlation (r = 0.57, p = 0.001, n = 29).

CONCLUSIONS

These results, together with thus far conducted studies on clinical applicability of the method, indicate that LDL-BDC is a promising candidate in search for a method for estimation of LDL oxidation in vivo.