Endocrinology and Metabolism

Original Articles

Difference of Thyroid Stimulating Antidody Activities Measured in Chinese Hamster Ovary Cells Stably Transfected with Human TSH Receptor and in FRTL-5 Cells in Graves Disease and Its Clinical Correlations.: Young Kee Shong Young Kee Shong, Hye Young Park, Bo Youn Cho, Won Bae Kim, Hong Gyu Lee, Chang Soon Koh, Yeon Sang Oh; J Korean Endocr Soc. 1996;11(1):18-29. Published online November 7, 2019

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Abstract PDF: Background
: Thyroid stimulating antibodies result in the development of hyperthyroidism and goiter in Graves disease. However, thyroid stimulating antibody activities do not correlate with the clinical features in many patients with Graves disease. The purpose of this study is to address this discrepancy between thyroid stimulating antibody activities and clinical features of Graves patients. Methods: We measured thyroid stimulating antibody activities simultaneously using human TSH receptor transfected Chinese hamster(hTSHR-CHO) cells and rat thyroid(FRTL-5) cells in 57 untreated patients with Graves disease, and compared their activities with clinical features including thyroid hormone levels. Results : The detection rate of thyroid stimulating antibody measured by hTSHR-CHO cells was 90% in 57 untreated Graves patients and it was higher than that measured by FRTL-5 cells. Thyroid stimulating antibody activity by hTSHR-CHO cells was significantly correlated with that by FRTL-5 cells(r=0.5, p<0.001), however, 18 of 57(32%) patients showed marked discrepancy of thyroid stimulating antibody activity between in hTSHR-CHO and FRTL-5 systems. Thyroid stimulating antibody activity measured by hTSHR-CHO cells was significantly correlated with serum total T3, free T4 levels, and goiter size but not 99mTc-thyroid uptake. On the other hand, thyroid stimulating antibody activity measured by FRTL-5 cells was significantly correlated with goiter size and 99mTc-thyroid uptake but not thyroid hormone levels. The difference between function and goiter size with respect to thyroid stimulating antibody measurement in two cells system is, nevertheless, particularly evident in the free T4/goiter ratio in patients with high hTSHR-CHO and low FRTL-5 cell assay values. Conclusion: These findings suggest that thyroid stimulating antibodies in Graves disease are heterogeneous population in terms of responses to different origin of cells. Further, thyroid stimulating antibody activities measured by FRTL-5 cells tend to correlate better with goiter size and Tc-thyroid uptake, whereas thyroid stimulating antibody activities measured by hTSH-CHO cells correlate better with thyroid hormone levels.

Assay of Thyrotropin Receptor Antibodies with Recombinant Human Thyrotropin Receptor Expressed on Chinese Hamster Ovary Cells.: Bo Youn Cho, Hong Kyu Lee, Chang Soon Koh, Jae Hoon Chung, Ka Hee Yi, Kyung Soo Ko, Won Bae Kim; J Korean Endocr Soc. 1995;10(4):347-361. Published online November 7, 2019

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Abstract PDF: Thyroid stimulating antibody which results in the development of hyperthyroidism and goiter in Graves' patients used to be measured by using rat thyroid cells, FRTL-5. However, this assay has disadvantages: decreased sensitivity due to differences in species, and fastidious culture conditions for FRTL-5 cells. Thus, we recently created stably transfected Chinese hamster ovary(CHO) cells containing the human TSH receptor(hTSHR-CHO) and developed optimal conditions for the measurement of thyroid stimulating antibody using hTSHR-CHO cells. In this study, to evaluate the clinical relevance of thyroid stimulating antibody measurement using hTSHR-CHO cells, we measured thyroid stimulating antibody activities of IgGs from Graves' disease and other thyroid disease using hTSHR-CHO cells, and compared to those of thyroid stimulating antibody assays using FRTL-5 cells. 1) The cut off value of positive thyroid stimulating antibody activity measured in hTSHR-CHO cells was 145%(above the mean +2SD) which was lower than 165% in FRTL-5 cells. The intra-assay and inter-assay variances were 3.9% to 9.0% and 12.7% to 1.6%, respectively. 2) Thyroid stimulating antibody activity was detected in 90% of patients with untreated Graves' disease when patients initially presented. Further, in patients seen initially but already under therapy, 75% had positive values if they were hyperthyroid but only 43% had IgGs with activity if they were euthyroid. Patients in clinical remission after therapy showed positive values in 23% of cases. Only 2 of 25 patients with Hashimoto's thyroiditis showed weak thyroid stimulating antibody activity, none of 18 patients with nodular nontoxie goiter, 1 of 15 patients with primary myxedema, and 2 of 33 control patients with no thyroid disease. Thus, the detection frequency and specificity of the assay with hTSHR-CHO cells was excellent for this type bioassay.3) The detection frequency of thyroid stimulating antibody activity by hTSHR-CHO cells assay system(90%) was higher than that by FRTL-5 cells assay system(66%) in untreated Graves' patients. Those two activities were positively correlated with each other(r=0.52, p<0.001). However, some IgGs showed discrepancy of the thyroid stimulating antibody activity measured in hTSHR-CHO cells and in FRTL-5 cells; 56 of 87 patients were positive in both cells system, 8 of 87 were negative in both cells system, 1 of 87 was only positive in FRTL-5 cells and 22 of 87 were only positive in hTSHR-CHO cell system. Thus, 73%(22/30) of IgGs showing negative values of thyroid stimulating antibody activities in FRTL-5 cells were detected its activities in hTSHR-CHO cells system.In summary, thyroid stimulating antibody assay with hTSHR-CHO cells exhibited so excellent sensitivity and specificity that this technique should be used for clinical practice as well as basic research.

Thyroid Stimulating Antibody Assay with Chinese Hamster Ovary Cells Expressing Human Thyroid Stimulating Hormone (TSH) Receptor; Optimization of Assay Condition.: Bo Youn Cho, Hong Kyu Lee, Young Kee Shong, Chang Soon Koh, Ka Hee Yi, Yeon Sahng Oh, Won Bae Kim; J Korean Endocr Soc. 1995;10(4):333-346. Published online November 7, 2019

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Abstract PDF: We investigated the optimal condition of thyroid stimulating antibody(TSAb) assay using Chinese hamster ovary cells transfected with cDNA of human TSH receptor(TSHr-CHO) stably expressing functional TSH receptors. The extracellular cAMP responses of TSHr-CHO cells to the stimulation of bTSH or Graves' IgG were observed in three different incubation media. Stimulation indices of extracellular cAMP were higher when sucrose containing NaCl-free isotonic Hank's balanced salt solution(HBSS)(media A)was used as incubation media than those of NaCl-free hypotonic HBSS(media B) or those of NaCl containing isotonic HBSS(media C). The incubation of TSHr-CHO cells in media B caused marked increase in the basal cAMP level without concomittant fold-increase in the stimulated cAMP level at various doses of bTSH and Graves' IgG. Decreasing the stimulation indices of extracellular cAMP, use of media B failed to detect TSAb activities in two TSAb-positive Graves' IgG tested. In case of media C, extracellular cAMP responses are poor at 0.001 and 0.1U/L of bTSH and at all doses of Graves' IgG tested(0.5, 1, 5g/L). The incubation of TSHr-CHO cells in media B caused significant increase in the number of trypan blue-stained, nonviable cells(5.7+-1.5, 7.6+-1.9 and 8.5+-1.6% at 1, 2 and 3h of incubation, respectively; p<0.01) comparing to those incubated in media A or media C(about 2-3% in both media). Those decrease in the viability of TSHr-CHO cells when incubated in hypotonic incubation media may explain the decrease in the stimulation index of extracellular cAMP with the use of media B in contrast to the case of FRTL-5 cells. TSAb assay of 87 consecutive fresh Graves' patients with TSHr-CHO cells using media A detected TSAb activities in 90%(78 patients) of them, and moreover TSAb activities showed significant positive correlation with the pre-treatment serum T_3 and free T_4 levels of those patients. We conclude that TSAb assay with TSHr-CHO cells is a sensitive and physiologically relevant assay system to measure TSAb activities merely through measurements of extracellular cAMP provided that the cells are incubated in NaCl-free isotonic incubation media.

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