Large scale screening programme for selection of antisera for radioimmunoassay of human parathyroid hormone

A large-scale, three-phase screening programme has been devised for the rapid selection of antisera which might be of potential use in clinical radioimmunoassays for human parathyroid hormone. A total of 122 sera from 169 guinea pigs and 6 rabbits immunized with bovine parathyroid hormone, and 12 guinea pigs immunized with human parathyroid hormone were assessed relative to reference antisera. Pre-determined criteria for the three phase programme were imposed by the requirement for antisera that could be used at dilutions greater than 10(-5) in order to ensure continuity of supplies for wide-spread distribution and by the limited availability of human parathyroid hormone for testing purposes. Of the sera tested, only 5 were selected as having high titre and sensitivity for low concentrations of human parathyroid hormone. The 5 antisera were further evaluated for amino- and carboxyl-region specificities for the human parathyroid hormone in comparison with antiserum 211/32, widely distributed for use in radioimmunoassay for clinical purposes. The selected antisera appear to be of high affinity with good recognition of the whole or carboxyl-region parts of the human parathyroid molecule.