Enzyme immunoassay for human apolipoprotein B, the major protein moiety in low-density- and very-low-density lipoproteins.
We used enzyme immunoassay to measure apolipoprotein B concentration in human plasma. Pure lipoprotein B was isolated from serum samples of fasting normolipidemic subjects by sequential preparative ultracentrifugation and coated to a polystyrene tube surface by adsorption. Human serum samples and rabbit antiserum to human apolipoprotein B were incubated with the solid-phase lipoprotein B. Soluble antigen competed with solid-phase antigen for binding to antibodies. After washing, peroxidase-labeled sheep antibodies against rabbit immunoglobulins were added, and after further washing the bound label was assayed. This provided a direct measurement of the soluble antigen. The best technical conditions for the assay were determined. The minimum detectable concentration was 1 microgram per assay. The enzyme immunoassay yielded values that compare favorably with those obtained by radial immunodiffusion (r = 0.84) and by rocket immunoelectrophoresis (r = 0.80). The assay offers several advantages over existing techniques: sensitivity, specificity, simplicity, ane non-use of radioisotopes.
D001053:Apolipoproteins / Q000097:blood*; D006801:Humans; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007124:Immunoenzyme Techniques; D008077:Lipoproteins, LDL / Q000097:blood*; D008079:Lipoproteins, VLDL / Q000097:blood*
D001053:Apolipoproteins; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL