Genetics
A new isoform-independent Lp(a) ELISA matches the gold-standard assay and mass spectrometry with over 97% correlation (J Lipid Res 2022)
Original title: Development and validation of an isoform-independent monoclonal antibody-based ELISA for measurement of lipoprotein(a)
Marcovina and colleagues developed and validated a new isoform-independent ELISA for Lp(a), using monoclonal antibody LPA4 for capture (targeting an apolipoprotein(a) KIV2 epitope) and LPA-KIV9 for detection (targeting a single KIV9 epitope). The assay measuring range spans 0.27 to 1,402 nmol/L and met CLIA and College of American Pathologists validation criteria for precision, linearity, spike-recovery, dilutability, and plasma-versus-serum comparison. In 64 samples with known apolipoprotein(a) isoforms, the new assay correlated strongly with the gold-standard ELISA (r=0.987) and an LC-MS/MS reference method (r=0.976), with apolipoprotein(a) isoform size explaining only 0.2% and 2.2% of bias variation respectively, confirming isoform independence. The findings establish the LPA4/LPA-KIV9 ELISA as equivalent to existing reference methods, supporting efforts toward standardised Lp(a) measurement.
Original abstract
The study aims were to develop a new isoform-independent enzyme-linked immunoassay (ELISA) for the measurement of lipoprotein(a) [Lp(a)], validate its performance characteristics, and demonstrate its accuracy by comparison with the gold-standard ELISA method and an LC-MS/MS candidate reference method, both developed at the University of Washington. The principle of the new assay is the capture of Lp(a) with monoclonal antibody LPA4 primarily directed to an epitope in apolipoprotein(a) KIV2 and its detection with monoclonal antibody LPA-KIV9 directed to a single antigenic site present on KIV9. Validation studies were performed following the guidelines of the Clinical Laboratory Improvement Amendments and the College of American Pathologists. The analytical measuring range of the LPA4/LPA-KIV9 ELISA is 0.27-1,402 nmol/L, and the method meets stringent criteria for precision, linearity, spike and recovery, dilutability, comparison of plasma versus serum, and accuracy. Method comparison with both the gold-standard ELISA and the LC-MS/MS method performed in 64 samples with known apolipoprotein(a) isoforms resulted in excellent correlation with both methods (r=0.987 and r=0.976, respectively). Additionally, the variation in apolipoprotein(a) size accounted for only 0.2% and 2.2% of the bias variation, respectively, indicating that the LPA4/LPA-KIV9 ELISA is not affected by apolipoprotein(a) size polymorphism. Peptide mapping and competition experiments demonstrated that the measuring monoclonal antibodies used in the gold-standard ELISA (a-40) and in the newly developed ELISA (LPA-KIV9) are directed to the same epitope, 4076LETPTVV4082, on KIV9. In conclusion, no statistically or clinically significant bias was observed between Lp(a) measurements obtained by the LPA4/LPA-KIV9 ELISA and those obtained by the gold-standard ELISA or LC-MS/MS, and therefore, the methods are considered equivalent.
Summary written by lp-a.org from the published abstract; figures as published. Page updated 18 August 2026. Methods.