Formation of LATS by Human Thyrotropin-Antibody Complexes1

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Abstract
The possibility that the biologic response of the thyroid to thyrotropin stimulation could be modified by an antibody was examined in a series of in vitro experiments. Human thyrotropin (HTSH) was incubated with varying concentrations of rabbit anti-HTSH serum (RAHTSH) for 1 hr at 37 C and 16 hr at 4 C followed by centrifugation and bioassay of the supernates by the McKenzie method. In the presence of 1:8 dilution of antiserum, the bioassay response of HTSH was effectively abolished; however, at 1:16 dilution, a long-acting response was observed (2 hr: 137±6; 8 hr: 202±19). Further dilution of the rabbit antiserum did not alter the usual maximal 2 hr bioassay response of HTSH. The modifying effect upon the HTSH response by the 1:16 dilution of RAHTSH could be abolished by prior incubation of the antiserum with goat antiserum to rabbit gamma globulin or by acid dissociation of the HTSH-RAHTSH complex followed by incubation with goat antiserum to rabbit gamma globulin. The necessity of a critical dilution of RAHTSH to produce a LATS-like bioassay response could be obviated by prior papain digestion of RAHTSH to produce monovalent Fab fragments. A maximal 8 hr response was consistently obtained when HTSH was incubated with varying concentrations of the papain-digested HTSH antiserum. These studies indicate it is possible to alter HTSH by specific antiserum to produce a LATStype response in a biologic assay.

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