[A novel Lp(a) assay not affected by apo(a) size polymorphism]

Area of Science:

• Biochemistry
• Immunology
• Clinical Chemistry

Context:

• Lipoprotein(a) [Lp(a)] is a lipoprotein particle implicated in cardiovascular disease risk.
• Apolipoprotein(a) [Apo(a)], the protein component of Lp(a), exhibits significant size polymorphism due to variable numbers of K4 type 2 repeats.
• Accurate quantification of Lp(a) is crucial for assessing cardiovascular risk, but size polymorphism poses a challenge for current assays.

Purpose:

• To develop and validate novel Enzyme-Linked Immunosorbent Assay (ELISA) methods for quantifying Lp(a).
• To evaluate the performance of different monoclonal antibodies targeting various apo(a) domains in ELISA assays.
• To assess the impact of apo(a) size polymorphism on Lp(a) measurement accuracy.

Summary:

• Three ELISA methods were developed using monoclonal antibodies against K4 type 2 repeats, K4 type 5-protease domain, and K5 protease domain of apo(a).
• Commercial assay kits showed poor correlation with ELISA using anti-Lp(a) K4 type 5-protease domain antibodies and overestimated Lp(a) in specific isoforms.
• A novel ELISA method utilizing the apo(a) K4 type 5-protease domain as both capture and labeled antibody demonstrated robustness against apo(a) size polymorphism.

Impact:

• The developed ELISA method provides accurate Lp(a) quantification, overcoming limitations of existing assays related to apo(a) size variation.
• This advancement can lead to more reliable cardiovascular risk assessment and personalized treatment strategies.
• Improved Lp(a) measurement accuracy facilitates further research into the role of Lp(a) in atherosclerosis and thrombosis.