Antigenic modification of polypeptides

A modified polypeptide for isoimmunologically controlling biological action in a mammal by antibody formation, the modified polypeptide comprising a peptide having an amino acid sequence in its unmodified form of:

• ##STR9## or a sequence substantially immunologically equivalent to one of these sequences, said peptide having the two cysteine residues corresponding to the cysteine residues at positions 38 and 57 of the beta-subunit of human chorionic gonadotropin having their sulfur atoms linked in a disulfide bridge, said peptide having been chemically modified outside the body of said mammal by coupling said peptide to a carrier selected from the group consisting of a diazosulfanilic acid, dinitrophenol, trinitrophenol, S-acetomercaptosuccinic anhydride, (poly)tyrosine, (poly)alanine, poly(lysine), (poly)dextran, thyroglobulin, natural proteins, polymerized sugars, serum protein, diphtheria toxoid and tetanus toxoid, said peptide having the properties of:
• (a) in unmodified form, being non-immunogenic to said mammal and having a molecular structure similar to a fragment of an endogenous protein hormone, the biological function of which it is desired to inhibit, and
• (b) in modified form, causing antibodies to be formed in the body of the mammal which inhibit the biological function of said endogenous protein hormone following administration of the modified form into the body of said mammal.