Binding characteristics of monoclonal antibodies raised against bovine growth hormone

Monoclonal antibodies have been raised against pituitary bovine growth hormone using the hybridoma procedure. The binding characteristics of the seven selected monoclonal antibodies toward the antigen molecule in its native, chemically or enzymatically treated form have been studied. The reactivities of the monoclonal antibodies with growth hormones from other species and bovine prolactin have also been investigated. The epitopes recognized by four of the produced monoclonal antibodies are conformational, whereas two other monoclonal antibodies bind to sequential determinants. Three antibodies define immunological sites located between residues 6-124 of the bovine growth hormone molecule, and one of this antibody shows higher affinity to human than bovine growth hormone. The immunoreactivity of one monoclonal antibody is enhanced by the previous binding of the antigen to polyclonal antibodies, probably because of a localized conformational change of the bovine growth hormone molecule. This antibody also shows cross-reactivity with all the homologous hormones tested, indicating to recognize a highly conserved antigenic determinant.