Evaluation and characterization of EIA measuring autoantibodies against oxidized LDL

Autoantibodies against oxidized LDL (oxLDL) have been measured in many labo ratories. Comparison of data between laboratories is difficult because of m ethodological variations and differences in the expression of results. We h ave optimized an enzyme immunoassay (EIA), which measures autoantibodies ag ainst oxLDL and evaluated the effect on results of different ways of expres sing the data. Optimized conditions were as follows: coating concentration 2 mug/ml of LDL on polysorp plates, 1% human serum albumin (HSA) as a block ing agent, sample dilution 1:50, conjugate dilution 1:8000, and 0.2% HSA in sample and conjugate diluents. The amount of autoantibodies expressed as r atios between oxLDL and native LDL (natLDL), as titers against oxLDL or as differences between binding to oxLDL and natLDL showed significant differen ces among groups of coronary heart disease (CHD) patients with different di agnosis or treatment procedures. However, there were no differences among t he groups when the results were expressed as the ratio between antibody tit er against oxLDL and a standard serum (oxLDL/stand). After standardization oxLDL autoantibody test may become a useful tool for analysis of the risk f or CHD. (C) 2001 Elsevier Science Inc.