Micro competition enzyme linked immunosorbant assay for human apolipoprotein B.

A solid phase micro competition enzyme linked immunosorbant assay (microCELIA) was developed to measure apolipoprotein B (Apo B) in human plasma. The soluble Apo B competed with the solid phase antigen for antibody binding. After washing, alkaline phosphatase labeled goat anti-rabbit IgG antibody was added and the plates were washed and assayed. The minimal quantifiable concentration of Apo B was one mg per L. This enzyme immunoassay (EIA) yielded values which correlated with values of samples assayed in reference laboratories by radioimmunoassay (RIA) (r = 0.97) and by electroimmunoassay (r = 0.92). The electroimmunoassay overestimates the activity of hyperlipemic samples compared to microCELIA. The assay offers advantages over other existing techniques including short incubation time, high sensitivity, technical simplicity, elimination of radioisotopes, low cost, and use of a universal enzyme label.