An immunochemical study of sheep pituitary interstitial cell-stimulating hormone

Rabbit antiserum to highly purified interstitial cell-stimulating hormones (ICSH) from sheep pituitary glands (βs-ICSH) has been produced. Various immunochemical studies indicated that βs-ICSH is a homogeneous protein. This antiserum was shown to form precipitable antibody-antigen complexes in crude extracts of rat and pig pituitaries. Injections of the antiserum into normal rats were found to inhibit the endogenous ICSH activity. Bioassay in either normal or hypophysectomized rats showed that the antiserum to βs-ICSH inhibits not only the activity of sheep ICSH but also that of pregnant mare serum gonadotropin and human ICSH. The ICSH activity of crude extracts of whale, pig, and rat pituitaries can be counteracted by simultaneous injections of the rabbit βs-ICSH antiserum, whereas the ICSH activity of human chorionic gonadotropin and chicken pituitary extract was not neutralized by the antiserum