Induction of experimental autoimmune Graves' disease in BALB/c mice

We immunized BALB/c mice with M12 cells (H-2(d)) expressing either mouse (m M12 cells) or human thyrotropin receptor (TSHR) (hM12 cells), Immunized mic e developed autoantibodies to native TSHR by day 90 and, by day 180, showed considerable stimulatory Ab activity as measured by their ability to enhan ce cAMP production (ranging from 6.52 to 20.83 pmol/ml in different treatme nt groups relative to 1.83 pmol/ml for controls) by TSHR-expressing Chinese hamster ovary cells. These mice developed severe hyperthyroidism with sign ificant elevations in both tetraiodothyronine and triiodothyronine hormones . Tetraiodothyronine levels in different experimental groups ranged from a mean of 8.66-12.4 mu g/dl, relative to 4.8 mu g/dl in controls. Similarly, mean triiodothyronine values ranged from 156.18 to 195.13 ng/dl, relative t o 34.99 ng/dl for controls. Next, we immunized BALB/c mice with a soluble e xtracellular domain of human TSHR (TBP), or TBP expressed on human embryoni c kidney cells (293 cells) (293-TBP cells). These mice showed severe hypert hyroidism in a manner very similar to that described above for mice immuniz ed with the mouse TSHR or human TSHR, and exhibited significant weightless, with average weight for treatment groups ranging from 20.6 to 21.67 g, whi le controls weighed 24.2 g, Early after onset of the disease, histopatholog ical examination of thyroids show-ed enlargement of colloids and thinning o f epithelial cells without inflammation, However, later during disease, foc al necrosis and lymphocytic infiltration were apparent. Our results showed that conformationally intact ectodomain of TSHR is sufficient for disease i nduction, Availability of a reproducible model in which 100% of the animals develop disease should facilitate studies aimed:at understanding the molec ular pathogenesis of Graves' disease.