Simple enzyme immunoassay for the simultaneous measurement of whole choriogonadotropin molecules and free beta-subunits in sera of women with abnormal pregnancies or tumors of the reproductive system

Abstract

A multiple enzyme immunoassay (multi-EIA) was developed to quantify whole-molecule human choriogonadotropin (w-hCG) and free hCG β-subunits (hCG-β) simultaneously. A clone of a specific monoclonal antibody was coupled to solid phase; two other clones of different monoclonal antibodies were conjugated to horseradish peroxidase (HRP; EC 1.11.1.7) and alkaline phosphatase (AP; EC 3.1.3.1), respectively. These two enzyme conjugates were mixed together to measure w-hCG or hCG-β, depending on the selection of the enzyme substrate. To measure w-hCG and hCG-β simultaneously, both enzyme substrates were used with the blended enzyme conjugates. The assay is simple and reproducible, and can be completed within 2 h with high specificity and sensitivity. We measured w-hCG and hCG-β in the sera of women with abnormal pregnancies and in patients with tumors of the reproductive system, and observed different hCG-β/w-hCG ratios in patients with various types of trophoblastic tumors.