Quantitation of human serum very low density apolipoproteins C-I, C-II, C-III and E by enzyme immunoassay.

An enzyme immunoassay for human serum very low density apolipoproteins C-I, C-II, C-III and E is described. The assay is competitive and uses polystyrene tubes with adsorbed monospecific antibodies to which is added intact very low density lipoprotein (VLDL) conjugated with alkaline phosphatase. Conjugate containing all the different apolipoproteins complexed with lipids was used for quantitation of each individual aplipoprotein. The coefficients of variation were 7 and 10% for within-run and between-run reproducibility, respectively, for the range 50-100 ng apolipoprotein in the 0.5 ml sample. A comparison between apolipoprotein assays in intact and delipidated VLDL is presented.