A particle concentration fluorescence immunoassay for Lp(a)

Area of Science:

• Biochemistry
• Immunology
• Clinical Chemistry

Background:

• Quantifying Lipoprotein(a) [Lp(a)] via immunoassay is challenging due to the significant size variability of its apolipoprotein (a) component.
• This variability, stemming from at least 24 alleles of the (a) gene, complicates accurate and consistent measurement.

Purpose of the Study:

• To develop a novel assay for Lipoprotein(a) [Lp(a)] quantitation that is independent of apolipoprotein (a) size variations.
• To establish a sensitive, reliable, and efficient method for measuring Lp(a) levels.

Main Methods:

• Utilized a mixture of monoclonal antibodies targeting apolipoprotein (a) [apo(a)], which do not cross-react with plasminogen or apolipoprotein (apo) B.
• Immobilized these antibodies onto microscopic beads to capture Lp(a) particles, followed by detection using a fluorescein-labeled monoclonal antibody to apo B.
• Employed specialized microtiter plates with filters to facilitate thorough washing and enhance assay sensitivity and affinity.

Main Results:

• The developed assay is unaffected by the size variations of apo(a) because it relies on the constant molecular weight of apolipoprotein (apo) B, present as a single particle per Lp(a).
• The use of antibody-coated beads significantly increased the sensitivity and affinity of the capture step.
• The assay demonstrated a wide working range and could be completed within 4 hours.

Conclusions:

• A robust and sensitive immunoassay for Lipoprotein(a) [Lp(a)] has been successfully developed, overcoming the long-standing challenge of apolipoprotein (a) size heterogeneity.
• This assay provides a reliable method for accurate Lp(a) quantitation, crucial for cardiovascular risk assessment.
• The methodology offers improved sensitivity and efficiency compared to existing methods.