An immunological study of a human pituitary interstitial cell-stimulating hormone

Several investigators have reported recently the production of rabbit antiserum to human urinary gonadotrophins, but no similar data have appeared with respect to human pituitary gonad-stimulating substances. However, an immunochemical investigation in this Laboratory has shown that a highly purified preparation of sheep pituitary interstitial cell-stimulating hormone (ICSH) is a potent antigen. The rabbit antiserum obtained in that work was highly specific for the antigen and was able significantly to counteract its ability to stimulate the ventral prostate in hypophysectomized rats. By the Ouchterlony double diffusion test in agar-gel and the quantitative precipitin technique, the sheep interstitial cell-stimulating hormone was demonstrated to be homogeneous. Moreover, antiserum to sheep interstitial cell-stimulating hormone was capable of neutralizing significantly the interstitial cell-stimulating hormone activity of pituitary extracts from the rat, pig and whale, as well as of purified preparations of human pituitary interstitial cell-stimulating hormone and pregnant mare serum gonadotrophin. Injected anti-serum to sheep interstitial cell-stimulating hormone was also shown to cause an inhibition of endogenous activity of the hormone in normal rats. The results of similar investigations on the antigenicity of human pituitary interstitial cell-stimulating hormone are reported here