Binding of immunoglobulin G from patients with autoimmune thyroid diseases to solubilized guinea pig fat cell membranes crosslinked with 125I-TSH.

Iida, Yasuhiro; Konishi, Junji; Murakami, Takashi; Kasagi, Kanji; Endo, Keigo; Kuma, Kanji; Torizuka, K

doi:10.1507/endocrj1954.33.333

Cited by 2 publications

(1 citation statement)

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“…Although the presence of Graves' Ig with positive TS-ab but neg¬ ative TBII-rc can be partly explained by the dif¬ ference in assay sensitivity, all these findings strongly suggest the heterogeneous nature of the TSH receptor autoantibodies. In this regard, the presence of TSH receptor-related antibodies which immunoprecipitate [125I]bTSH receptor complexes has been reported (39). Furthermore, coexistence of blocking type antibodies, or adenylate cyclase inhibitor with stimulating type antibodies in sera from patients with Graves' disease is to be consid¬ ered (6,40,41).…”

Section: Discussionmentioning

confidence: 99%

Simultaneous measurement of TSH-binding inhibitor immunoglobulin and thyroid stimulating autoantibody activities using cultured FRTL-5 cells in patients with untreated Graves' disease

Lü

Kasagi²,

Hidaka³

et al. 1990

Acta Endocrinologica

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A new and practical assay was developed using cultured FRTL-5 cells for simultaneous assessment of TS-ab and TSH-binding inhibitor immunoglobulin, allowing direct comparison of these two activities under the same conditions. Subsequent to the TS-ab assay in which extracellular cAMP concentration in Hanks' medium without NaCl was determined, [125I]bTSH in this medium was added to observe the ability of serum Ig to inhibit the binding of [125I]bTSH to FRTL-5 cells. We found a much higher specific binding of [125I]bTSH to FRTL-5 cells and a much greater inhibition of [125I]bTSH binding to the cells exposed to Graves' Ig in hypotonic NaCl-free than in NaCl containing Hanks' medium, indicating that the binding of both TSH and Graves' Ig to the TSH receptor was salt-sensitive. The inhibitory activity of [125I]bTSH binding to the cells was 0.2\m=+-\4.6%(mean \m=+-\sd) in 45 normals. Inter-assay coefficients of variation in two positive controls with the mean values of 18.0 and 65.8% were 15.8 and 16.5%, respectively. Among 46 patients with untreated hyperthyroidism owing to Graves' disease, 45 (97.8%) were positive for TS-ab; 35 (76.1%) and 40 (87.0%) were positive for TSH-binding inhibitor in Ig assays using FRTL-5 cells and solubilized porcine thyroid membranes, respectively. TS-ab activities correlated less closely with TSH-binding inhibitory activities determined using FRTL-5 cells (r=0.576, p<0.001) than with those determined using porcine thyroid membranes (r=0.745, p<0.001). The correlation between TSH\x=req-\ binding inhibitory activities determined by the two methods, although statistically significant (r=0.537, p<0.001) was rather rough. Some patients clearly demonstrated discrepant results, suggesting the existence of heterogeneous populations of TSH receptor antibodies.It is well known that thyrotropin receptor anti¬ bodies present in serum of patients with Graves' disease are responsible for the development of hy¬ perthyroidism. These antibodies are called thy¬ roid-stimulating autoantibody (TS-ab) or TSHbinding inhibitory immunoglobulin (TBII), ac¬ cording to the different methods employed in the assay systems. TS-ab is considered to stimulate thy¬ roid function through the adenylate cyclase system and its stimulating activity can be assessed by mea¬ suring the cAMP production using thyroid cells (1,2). The TS-ab assay can be made considerably more sensitive by incubating cultured thyroid cells in hypotonie medium (1), more rapid, and more reproducible by using cell strain 4). TBII, on the other hand, can inhibit the binding of [12T]TSH to its receptor in radioreceptor assay using crude or detergent solubilized thyroid mem¬ branes (5-7).Since the establishment by Ambesi-Impiombato et al. (8), FRTL-5 cells have frequently been used for studies on thyroid cell growth, differentiation and function, and a number of papers have been published using this cell line (reviewed in 9). In accordance with the biological response to TSH, such as cAMP production, iodine uptake and thymidine incorporation, specific and s...

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Section: Discussionmentioning

confidence: 99%