Experimental parathyroid hormone deficiency produced by injection of antibodies to bovine parathyroid hormone

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Abstract
Antiserum to bovine parathyroid hormone (Anti-PTH) was produced in guinea pigs by repeated subcutaneous injections of purified bovine PTH with Freund's adjuvant. Specific binding of PTH with Anti-PTH was demonstrated in vitro by a two-antibody system. Anti-PTH was administered intravenously to three species of animals. Within 8 h, rats had developed a decrease in plasma calcium and an increase in plasma phosphorus concentrations, physiological changes characteristic of the PTH deficiency state. A similar degree of hypocalcemia occurred in rabbits. Some of the animals injected with Anti-PTH died within 24 h; in survivors, the hypoparathyroid state was transient and recovery occurred within 24 h. Equivalent amounts of Anti-PTH had no effect on the levels of plasma calcium in normal guinea pigs. Injections of parathyroid extract to rats, rabbits, and guinea pigs caused a hypercalcemic response. Since antibodies produced in the guinea pig to bovine PTH neutralized the physiological action of rat and rabbit PTH, but did not neutralize that of guinea pig PTH, it is concluded that bovine, rat, and rabbit PTH are immunologically similar, but that guinea pig PTH is dissimilar. However, the hormones of all four species have a common attribute that determines biological activity.