Lipoprotein(a)-Cholesterol Assay by Lectin Precipitation

Lipoprotein(a) [Lp(a)] is a cholesterol-rich particle that contributes to the total risk of coronary heart disease (CHD) when plasma levels are elevated. Elevated Lp(a) levels can be treated with niacin. Lp(a) differs from other lipoproteins by the presence of a glycoprotein, called apolipoprotein(a) [apo(a)], which is present in numerous isoforms that vary by size and creates significant error in assays that measure Lp(a) mass. We will measure and standardize Lp(a) by its cholesterol content [Lp(a)-c], a relatively stable component of Lp(a) that does not vary with isoform size. Specifically, Lp(a) will be separated from other lipoproteins by a lectin precipitation process devised by the applicant. Lp(a)-C will be determined in the precipitin by standard enzymatic methods. Lectin binding is a rapid and inexpensive method to separate glycoproteins by variation in polysaccharide content. Measurement of Lp(a)-c introduces less error than Lp(a) mass, as a result it is more amenable to standardization and allows for direct comparison of Lp(a) to other lipoproteins because they are routinely measured by their cholesterol content. Preliminary data indicates a high correlation of Lp(a)-c with Lp(a) mass, utilizing a standardized cholesterol assay. This assay would provide an inexpensive test similar to HDL cholesterol, for the assessment of CHD risk.