ELISA of lgG Antibody to Oxidized Low-Density Lipoprotein: Effects of Blocking Buffer and Method of Data Expression

We describe an ELISA for serum lgG antibodies against malondialdetiyde-modifledlow-density lipoprotein(mLDL). Optimal antigen concentration,serum dilution,and dilution of enzyme-conjugated second antibody were 25 mg/L, 1:250, and 1:5000, respectively, when 5 gIL human serum albuminwas used for blocking.When data were expressed as mLDL/LDL (the ratio of lgG binding to mLDL vs LDL), within-run and between-run CVs were 7.0 % and 8.9%, respectively.Antibody concentrationsexpressed as mLDL/ LOL or as mLDL-LDL (the difference between lgG binding to mWL and to LDL) were higher in women with systemic lupus erythematosus (n = 20) than in controls (n = 20) (P <0.001). With bovine serum albumin or Superblock blockingbuffers,onlythe mLDL- LOL data were significant. Thus, the choice of blockingagent and the method of dat