Production of antibodies specific to human chorionic gonadotropin in mice immunized against its chemical analogs

Abstract

Mice immunized against DS₅-hCG-β and DS₆-hCG-β, chemical analogs of β-subunit of human choriogonadotropin (hCG-β) in which 5 and 6 disulphide bonds respectively were reduced and alkylated, were found to produce antibodies specific to hCG without significant crossreactivity with human lutropin (hLH) as tested in a radioimmunoassay. In contrast, mice immunized against the native hCG-β subunit produced hLH crossreacting antibodies. While the anti-DS₅, DS₆-hCG-β serum was capable of selectively blocking the binding of [¹²⁵I]-hCG to rat testicular LH/hCG receptors, it failed to inhibit the binding of [¹²⁵I]-hLH to the same receptors. The radioimmunoassay for hCG using the mouse anti-DS₅, DS₆-hCG-β serum was not as sensitive as that employing rabbit anti-DS₅, DS₆-hCG-β serum. The minimal detection limit was 5 ng/ml for the mouse antibody as compared to 1 ng/ml for the rabbit antibody.