Monoclonal antibodies to beta subunit of choriogonadotropin: development and use in a sandwich ELISA pregnancy test.

Balb/c mice were immunized with beta subunit isolated and purified from crude human chorionic gonadotropin preparations. Spleen cells from the higher titered mouse were fused with Sp 2/0 myeloma cells. Four specific secreting hybridomas were obtained. Specificity, affinity, and suitability of secreted antibodies for use in enzyme immunoassays were studied. Ascites of the selected hybridoma was raised; the antibody was purified by protein A-affinity chromatography and coupled to horseradish peroxidase. This conjugate was employed in a simultaneous sandwich enzyme immunoassay on microtiter plates sensitized with goat polyclonal antibody to measure the hormone. The test has a sensitivity of 10 mlU/ml either on urine, serum, or plasma samples when read in a microplate reader. The results can also be evaluated by the naked eye, with a sensitivity of 20 mlU/ml. No cross reactivity was detected with other human gonadotropins.