ApoB-INDEPENDENT ENZYME IMMUNOASSAY FOR LIPOPROTEIN(a) BY CAPTURE ON IMMOBILIZED LECTIN (JACALIN)

Abstract

Enzyme immunoassay for lipoprotein(a) [Lp(a)] using antibodies to both apoB and apo(a) subunits (a-B assay) is shown to be affected by differential masking of apoB by apo(a) and the presence of LDL-Lp(a) adducts. An apoB-independent immunoassay by capturing Lp(a) through its O-glycans on microplate-coated lectin jacalin and quantitation using peroxidase-labeled anti-apo(a) (J-a assay) is described. J-a assay response is linear, more than twice as sensitive as a-B assay, and is suppressed only 18 ± 5% by non-Lp(a) O-glycan-containing proteins of serum. Wide variations in IgA did not significantly affect Lp(a) binding to jacalin (CV = 6.4%).

Keywords:

• enzyme-linked immunoassay
• jacalin
• lipoprotein(a)

ACKNOWLEDGMENT

A fellowship to Ms. Anuradha Sreekumar was received from the Council of Scientific and Industrial research, Government of India. The authors are grateful to the Division of Blood Transfusion Services of this institute for gift of serum and outdated plasma samples.

Notes

^a Absorbance of avidin-HRP binding to biotinylated Lp(a) captured from biotinylated JL1 dilution on coated jacalin, Figure 5.

^b IgA assay of plasma samples in Figure 5.

^c IgA assay of eight other random plasma samples.