Further Observations on the Question of Specificity of Antihuman Growth Hormone Rabbit Serum

Abstract

It recently has been demonstrated by several investigators (10–14) that highly purified human growth hormone (HGH) possesses significant lactogenic (prolactin) activity. In the present investigation, it was shown by the local crop sac test in immature pigeons that a 6-μg daily dose of HGH (Li) elicited a good lactogenic (crop sac stimulating) reaction, and that this response could be eliminated by prior treatment of the hormone with anti-HGH (Raben) rabbit serum, whereas treatment of the hormone with an equivalent amount of normal rabbit serum did not have any effect on this activity of the HGH. Results of agar diffusion tests (Ouchterlony) with crude human pituitary extracts demonstrated that anti-HGH (Raben) serum contained antibodies to at least 2 closely related antigenic components other than serum proteins and also a small amount of antibodies to human serum albumin. However, agar diffusion tests, including immuno-electrophoresis, showed the presence of only one antigenic component in highly purified HGH (Li or Raben). The possibility of the association of 2 biologic activities with the same molecule is discussed. On the other hand, the use of the newer technique of immuno- diffusion and immuno-electrophoresis in cellulose acetate consistently revealed the presence of several antigenic components other than serum proteins in the hormone preparations. The possible significance of this finding is discussed.