Monoclonal Antibody Specific to the Beta Subunit of Human Chorionic Gonadotropin (hCG) and Capable of Agglutinating hCG-Coated Red Blood Cells

Spleen cells of BALB/c mice immunized with human chorionic gonadotropin (hCG) were fused with NS-1 mouse myeloma cells. A hybrid cell line, clone PE4 secreting monoclonal antibody (MAb) to hCG was isolated by simultaneous screening with both a radioimmunoassay (RIA) and a hemagglutination inhibition assay (HAI). With the aid of the double-antibody radioimmunoassay, it was established that PE4-MAb recognizes the betasubunit of hCG. It shows an affinity constant of 0.4 x 10¹⁰ L/M and cross-reactivity of 0.1% to other related human glycopeptide hormones. PE4-MAb agglutinates sheep red blood cells coated with hCG and can be used in an HAI assay for hCG. Dual screening procedures have, thus, led to a monoclonal antibody showing high sensitivity in two different assays, and hence useful for the qualitative detection and quantitative determination of hCG by both RIA and HAI methods.