INHIBITION BY NORMAL IMMUNOGLOBULINS OF THYROTROPHIN-STIMULATED PRODUCTION OF CYCLIC AMP IN SLICES OF NORMAL HUMAN THYROID

Abstract

Slice preparations of normal human thyroid tissue have been used to investigate the effect of normal immunoglobulin G (IgG) on thyrotrophin (TSH)-induced accumulation of cyclic AMP. Incubation of slices in the presence of both TSH and normal IgG for 20 min reduced the stimulation of cyclic AMP accumulation elicited by TSH alone by approximately 30%. However, preincubation of slices with IgG for 100 min before addition of TSH virtually abolished the response to TSH. The latter effect of normal IgG was reversible, and removal of IgG before exposure to TSH allowed an unimpaired cyclic AMP response to TSH. The implications of these observations with respect to the application of this system to the functional bio-detection of thyroid-stimulating antibodies in IgG fractions from thyrotoxic sera are discussed.