Quantitative Studies of the Reaction of Bovine Thyrotropin Antiserum with Human and Bovine Thyrotropin Preparations.

Summary Two kinds of immunological comparisons between several bovine and human preparations of thyrotropin (TSH), including an I131-labeled bovine preparation, were made with the use of a rabbit antiserum against a purified bovine preparation. Using erythrocytes sensitized with a sample of the immunizing antigen, the inhibition of hemagglutination demonstrated cross-reaction between a crude human TSH preparation and anti-bovine TSH serum, but degree of inhibition was not proportional to biological activity when 3 bovine preparations were compared. Both the in vivo mouse I131 release and the in vitro bovine thyroid slice bioassay showed that the antiserum neutralized TSH. Results from the 2 assays were in agreement. Crude human TSH preparations required considerably more antiserum per unit of biological activity than did either crude or purified bovine TSH preparations. The labeled bovine preparation retained both biological potency and immunological integrity.