IMMUNOLOGICAL RELATIONSHIPS AMONG OVINE GLYCOPROTEIN HORMONES

Abstract

An antiserum to partially purified ovine FSH (but essentially free of LH) bound ¹²⁵I-labelled ovine LH or bovine TSH. The antibody was directed exclusively against determinants in the α subunit. In a radioimmunoassay, only the intact ovine and bovine hormones and their α subunits were reactive; the hormone specific β subunits exhibited no cross-reaction. The antibody directed against the α subunit was highly dependent on conformation. Human LH, FSH, TSH or their α subunits did not cross-react in the radioimmunoassay. Structural modifications such as acylation of the amino groups, reduction and alkylation of the S—S-bridges, or performic acid oxidation of the intact ovine FSH, LH or their α subunits virtually eliminated immunological reactivity. Using the α subunit radioimmunoassay, the presence of a significant quantity of free intact α subunit in standard (NIH) preparations of TSH-B7, FSH-S10 and LH-S19 was demonstrated.