A Sandwich Enzyme-Linked Immunosorbent Assay for β₂-Glycoprotein I

Abstract

SUMMARY.A solid-phase sandwich enzyme-linked immunosorbent assay for determining 0,-glycoprotein I in urine has been developed. It has a working concentration range of 5-40 pg/L and a detection limit of approximately 1 . 4 pg/L. The withinplate coefficient of variation (CV) falls between 1.4% and 2 -1 % , and the betweenbatch CV ranges from 5.2 to 6.0%. Recovery of P,-glycoprotein I added to urine varies between 96 and 110%. The assay can also be used for determining P,-glycoprotein I in serum. Additional key phrases: Apolipoprotein-H; renal tubular disordersBeta-2-glycoprotein I was identified in the perchloric acid soluble fraction of human plasma in 1961.' It has a molecular mass of approximately 50 kDa and has been shown to consist of 326 amino acids with five attached glucosaminecontaining oligosaccharides.2 Several forms have been found and genetic studies indicate that three allelic variants are coded at a single gene IOCUS.~

Sensitive Assays for Urinary Retinol-Binding Protein and β-2-Glycoprotein-1 Based on Commercially Available Standards

“…Previous work in our own laboratory has shown that urinary f32G I dilutes in parallel with purified serum standard up to a level of around 40 /lg/L, 13 although the exact level depends on the individual urine. Unfortunately, the only commercial standard available is purified from plasma rather than urine.…”

Circulating levels of β2-glycoprotein I in thrombotic disorders and in inflammation

“…31,[44][45][46][47][48][49][50][51] Interestingly, a significant positive correlation was observed between age and serum ␤2GPI levels in healthy individuals. This is in agreement with previous reports [45][46][47][48][49][50][51] that showed that older healthy individuals have significantly higher serum ␤2GPI concentrations than their younger counterparts. The higher levels associated with increasing age could indicate increasing synthesis of ␤2GPI or reduced catabolism.…”

Urinary Retinol Binding Protein: Stability and Pre-Analytical Handling of Specimens for its Measurement

“…Then 100 iLL of diluted samples and standards (l:20 dilution in PBS containing 1% Tween 20) were added in duplicate to appropriate wells. To reduce inter-well variability, the arrangement described by Sansom et al 13 was adopted. After incubation at 4°C overnight, plates were then washed as described above and 100 iLL peroxidase conjugated antibody (1:500 dilution in PBS/I % Tween 20) added to each well.…”