Human lipoprotein(a) quantified by 'capture' ELISA.

Area of Science:

• Cardiovascular Medicine
• Clinical Chemistry
• Immunology

Background:

• Plasma lipoprotein(a) (Lp(a)) is a significant genetically determined risk factor for early atherosclerosis (AS) and coronary artery disease (CAD).
• Accurate measurement of Lp(a) is vital for predicting cardiovascular events, especially in specific subpopulations.
• Existing methods may have limitations in specificity or interference.

Purpose of the Study:

• To develop and validate a sensitive and specific enzyme-linked immunosorbent assay (ELISA) for quantifying human plasma Lp(a).
• To assess the interference of common substances like LDL, plasminogen, lipids, hemoglobin, and bilirubin on the assay.
• To establish reference ranges and evaluate Lp(a) distribution in different demographic groups.

Main Methods:

• A 'capture' ELISA utilizing immobilized polyclonal rabbit anti-Lp(a) antibody.
• Detection with a monoclonal murine antibody recognizing Lp(a), followed by alkaline phosphatase-conjugated secondary antibody.
• Colorimetric detection using para-nitrophenyl phosphate substrate, with quantitation against a clinical standard.

Main Results:

• The developed ELISA is sensitive and specific, with no interference from LDL, plasminogen, lipids, hemoglobin, or bilirubin.
• Plasma Lp(a) distribution in healthy Caucasians is skewed, with a median of 80 mg/L.
• Elevated Lp(a) levels (>300 mg/L) are associated with increased relative risk for early myocardial infarction (MI), affecting approximately 20% of Caucasians.

Conclusions:

• The described ELISA provides a reliable method for measuring plasma Lp(a).
• Higher Lp(a) levels significantly increase the risk of early myocardial infarction.
• Distinct Lp(a) distributions in Black populations and Caucasian type II diabetics necessitate race-specific interpretation and further research.