Quantitation of human serum apolipoprotein B by enzyme immunoassay

An enzyme immunoassay for human serum apolipoprotein B is described. The assay is competitive and uses cellulose nitrate coated polystyrene tubes with adsorbed monospecific antibodies, to which is added intact low density lipoprotein (LDL) conjugated with alkaline phosphatase. The coefficients of variation were 8 and 10% for within-run and between-run reproducibility respectively, for the range 100-200 ng of apolipoprotein B in the sample. Recovery determinations on isolated very low and low density lipoprotein fractions showed good yields of immunologically determined apolipoprotein B relative to chemically determined apolipoprotein. Using this method on a control material of apparently healthy 40-60 year old men a good correlation (r = 0.67, p = 0.01) was found between serum apolipoprotein B content and serum LDL cholesterol.