A cyclic peptide significantly improves thyroid function, thyrotropin-receptor antibodies and orbital mucine /collagen content in a long-term Graves' disease mouse model.

BACKGROUND: BALB/c mice which received long-term immunizations of adenovirus (Ad) expressing thyrotropin receptor A-subunits (TSHR) developed stable Graves' disease (GD). TSHR-derived cyclic peptide 19 (P19) was identified as effective therapy in this model. METHODS: In Ad-TSHR mice, we investigated shorter disease intervals up to 4 months for histological alterations of the orbits, fine tuning of anti-TSHR antibodies (Ab) and free thyroxine (fT4) hormone levels by using novel detection methods in an independent laboratory. Therapy (0.3 mg/kg P19 or vehicle) was given intravenously after the fourth Ad-TSHR immunization (week 11) and continued until week 19. RESULTS: Thyrotropin binding inhibitory immunoglobulins (TBII, bridge immunoassay), blocking (TBAb) and stimulating (TSAb) TSHR-Ab (both cell-based bioassays) and serum levels of fT4 were significantly elevated at week 11 in Ad-TSHR-immunized mice versus none in control mice. For the first time, TSAb, TBAb, and thyroperoxidase-Ab were detected in 17 of 19, 12/19 and 6/19 Ad-TSHR immunized mice, respectively at week 21. Also, for the first time, this study showed that P19 treatment markedly reduced serum TBII (p < 0.0001), serum fT4 (p = 0.02), and acidic mucins and collagen content in the orbital tissue of Ad-TSHR-immunized mice. CONCLUSION: P19 significantly improved thyroid function, confirming previous results in an independent second laboratory. A relevant shift of anti-TSHR antibody subpopulations in response to P19 therapy may help explain its immunological effects. Moreover, P19 exerted a beneficial effect on mucine and collagen content of orbital tissue. Hence, P19 offers a potential novel therapeutic approach for GD and associated orbitopathy.

Comparison of a Novel Homogeneous Cyclic Amp Assay and a Luciferase Assay for Measuring Stimulating Thyrotropin-Receptor Autoantibodies.

OBJECTIVE: Stimulating thyrotropin-receptor antibodies (TSAb) cause Graves' disease (GD). We tested a novel homogeneous fluorescent 3',5' cyclic adenine monophosphate (cAMP) assay for the detection of TSAb in a bioassay. METHODS: Chinese hamster ovary (CHO) cell lines expressing either a chimeric (MC4) or wild-type (WT) TSH-R were incubated with the adenyl cyclase activator forskolin, a human TSAb monoclonal antibody (M22), and with sera from GD patients. Intracellular cAMP levels were measured using a Bridge-It® cAMP assay, and the results were compared with a luciferase-based bioassay. RESULTS: Both cell lines were stimulated with forskolin concentrations (0.006-200 µM) in a dose-dependent manner. The linear range in the MC4 and WT cells was 0.8-25 and 3.1-50 µM, respectively. Levels of cAMP and luciferase in forskolin-treated MC4 and WT cells were positively correlated (r = 0.91 and 0.84, both p < 0.001). The 50% maximum stimulatory concentration of forskolin was more than 16-fold higher for the CHO-WT cells than the CHO-MC4 cells in the cAMP assay and 4-fold higher in the luciferase assay. Incubation of both cell lines with M22 (0.006-50 ng/mL) resulted in a dose-dependent increase in cAMP levels with linear ranges for the MC4 and WT cells of 0.8-12.5 and 0.2-3.125 ng/mL, respectively. Comparison of cAMP and luciferase levels in M22-treated MC4 and WT cells also showed a positive correlation (r = 0.88, p < 0.001 and 0.75, p = 0.002). A positive correlation was also noted when using patient samples (r = 0.96, p < 0.001) that were all TSH-R-Ab binding assay positive. CONCLUSION: The novel, rapid, simple-to-perform cAMP assay provides TSAb-mediated stimulatory results comparable to a luciferase-based bioassay.

A Novel Long-Term Graves' Disease Animal Model Confirmed by Functional Thyrotropin Receptor Antibodies.

INTRODUCTION: A novel long-term murine model for Graves' disease (GD) using repeated, long-term immunizations with recombinant adenovirus expressing the extracellular A-subunit of the human thyrotropin receptor (Ad-TSHR) was applied to evaluate the functional anti-TSHR-antibody (TSHR-Ab) profile. METHODS: BALB/c mice received 7 immunizations with either 1010 plaque-forming units of Ad-TSHR or control Ad-GFP. Naïve (nonimmuized native) mice were also studied. Three 3-weekly immunizations were followed by 4-weekly boosts until the 7th immunization. Blocking (TBAb) and stimulating (TSAb) TSHR-Ab were measured with bioassays. Assay cut-offs for TBAb/TSAb were at 34% inhibition and a specimen-to-reference ratio (SRR) of 140%. RESULTS: Nineteen (8 Ad-TSHR-, 4 Ad-GFP-immunized, and 7 native) mice were investigated. All native mice were negative for TSHR-binding inhibitory immunoglobulins (TBII) prior to immunization. Native and Ad-GFP mice were negative in weeks 17 and 27 for TBII and TBAb/TSAb. In native mice, the free thyroxine (fT4) levels (median [25th percentile; 75th percentile]) were in the upper normal range (1.2 ng/mL [1.1; 1.6]) prior to immunization, at weeks 17 (2.2 ng/mL [2.1; 2.4]) and 27 (1.4 ng/mL [1.1; 1.7]), respectively. In contrast, in Ad-TSHR-immunized mice, fT4 values were markedly increased at weeks 17 (4.4 ng/mL [3.9; 6]) and 27 (4.5 ng/mL [4.2; 6]) compared to those in Ad-GFP mice (2 ng/mL [1.8; 2.1] and 1.4 ng/mL [1.1; 1.6]), respectively (p = 0.0008, p = 0.001). In contrast, at week 17, in Ad-TSHR mice, the mean TBII, TBAb, and TSAb levels were 40 IU/L (40; 40); 62% inhibition (38; 69), and 116% SRR (97; 185), respectively; at week 27, they were 40 IU/L (39; 40); 65% inhibition (34; 80) and 95% SRR (63; 187), respectively. Three serum samples from Ad-TSHR mice (38%) demonstrated dual TBAb/TSAb positivity. CONCLUSIONS: TBAb/TSAb were highly prevalent in Ad-TSHR-immunized mice, thus confirming the successful establishment of a novel, long-term murine model for GD. All TBAb- and TSAb-positive Ad-TSHR-immunized mice were TBII-positive. Thus, the binding immunoassay did not differentiate between TSHR-Ab functionality.

Prospective Trial of Functional Thyrotropin Receptor Antibodies in Graves Disease.

CONTEXT: Scarce data exist regarding the relevance of stimulatory (TSAb) and blocking (TBAb) thyrotropin receptor antibodies in the management of Graves disease (GD). OBJECTIVE: To evaluate the clinical utility and predictive value of TSAb/TBAb. DESIGN: Prospective 2-year trial. SETTING: Academic tertiary referral center. PATIENTS: One hundred consecutive, untreated, hyperthyroid GD patients. METHODS: TSAb was reported as percentage of specimen-to-reference ratio (SRR) (cutoff SRR < 140%). Blocking activity was defined as percent inhibition of luciferase expression relative to induction with bovine thyrotropin (TSH, thyroid stimulating hormone) alone (cutoff > 40% inhibition). MAIN OUTCOME MEASURES: Response versus nonresponse to a 24-week methimazole (MMI) treatment defined as biochemical euthyroidism versus persistent hyperthyroidism at week 24 and/or relapse at weeks 36, 48, and 96. RESULTS: Forty-four patients responded to MMI, of whom 43% had Graves orbitopathy (GO), while 56 were nonresponders (66% with GO; P < 0.01). At baseline, undiluted serum TSAb but not thyroid binding inhibitory immunoglobulins (TBII) differentiated between thyroidal GD-only versus GD + GO (P < 0.001). Furthermore, at baseline, responders demonstrated marked differences in diluted TSAb titers compared with nonresponders (P < 0.001). During treatment, serum TSAb levels decreased markedly in responders (P < 0.001) but increased in nonresponders (P < 0.01). In contrast, TBII strongly decreased in nonresponders (P = 0.002). All nonresponders and/or those who relapsed during 72-week follow-up period were TSAb-positive at week 24. A shift from TSAb to TBAb was noted in 8 patients during treatment and/or follow-up and led to remission. CONCLUSIONS: Serum TSAb levels mirror severity of GD. Their increase during MMI treatment is a marker for ongoing disease activity. TSAb dilution analysis had additional predictive value.

Comparison of a Bridge Immunoassay with Two Bioassays for Thyrotropin Receptor Antibody Detection and Differentiation.

A rapid and fully automated chemiluminescent immunoassay for the detection of thyrotropin receptor autoantibodies (TSHR-Ab) based on a bridge technology was compared with two bioassays that measure either stimulating (TSAb) or blocking (TBAb) antibodies for the detection and differentiation of TSHR-Ab. A total of 229 patients with various thyroid disorders [151 with Graves' disease (GD), 35 with Hashimoto's thyroiditis (HT), 32 with nodular goiter, and 11 with thyroid cancer] were included. The bridge immunoassay was performed according to the manufacturer's instructions (cut-off>0.55 IU/l). TSAb and TBAb were measured with reporter bioassays. Blocking activity was defined as percent inhibition of luciferase expression relative to induction with bovine TSH alone (cut-off>34% inhibition). TSAb was reported as percentage of specimen-to-reference ratio (> 140 SRR%). The 3 TSHR-Ab assays were negative in all patients with benign euthyroid nodular goiter and differentiated thyroid cancer. In contrast, in all patients with GD, irrespective of the disease duration, TSHR-Ab positivity was present in 127 of 151 (84%) and 140 (93%) for the bridge assay and TSAb bioassay, respectively (p<0.001). Fifteen of 151 (10%) GD samples were positive in the TSAb bioassay but negative in the bridge assay. The bridge assay and the TSAb bioassay correlated positively (r=0.39, p<0.0001) in patients with GD. Both assays detected TSHR-Ab in all ten untreated hyperthyroid patients with GD. In GD patients with a duration of less than six months, 27/29 (93%) and 28 (97%) were TSHR-Ab positive with the bridge and TSAb bioassay, respectively. In comparison, TSHR-Ab were present in two of 35 (6%) and five (14%) HT patients with the bridge and TSAb bio-assay, respectively. TSHR blocking antibodies were present in one (3%) patient with HT and in two (1%) patients with GD; these two GD patients were also bridge assay positive but TSAb bioassay negative. In conclusion, the bridge immunoassay and both bioassays are highly sensitive for the detection of TSHR-Ab. The bridge assay is, however, also positive in the presence of TSHR blocking antibodies detected in a TBAb bioassay.

Stimulatory TSH-Receptor Antibodies and Oxidative Stress in Graves Disease.

Context: We hypothesized that TSH-receptor (TSHR) stimulating antibodies (TSAbs) are involved in oxidative stress mechanisms in patients with Graves disease (GD). Methods: Nicotinamide adenine dinucleotide phosphate oxidase, isoform 2 (NOX2); oxidative parameters; and oxidative burst were measured in serum, urine, and whole blood from patients with GD and control subjects. Superoxide production was investigated in human embryonic kidney (HEK)-293 cells stably overexpressing the TSHR. Lipid peroxidation was determined by immunodot-blot analysis for protein-bound 4-hydroxy-2-nonenal (4-HNE) in human primary thyrocytes and HEK-293-TSHR cells. Results: Serum NOX2 levels were markedly higher in hyperthyroid untreated vs euthyroid treated patients with GD, hyperthyroid patients with toxic nodular goiter, and euthyroid healthy control subjects (all P < 0.0001). Urine oxidative parameters were increased in patients with GD vs patients with toxic goiter (P < 0.01) and/or control subjects (P < 0.001). The maximum of the zymosan A- and phorbol 12,13-dibutyrate-induced respiratory burst of leukocytes was 1.5-fold higher in whole blood from hyperthyroid patients with GD compared with control subjects (P < 0.001 and P < 0.05). Monoclonal M22 TSAbs stimulated cAMP (HEK cells) in a dose-dependent manner. M22 (P = 0.0082), bovine TSH (P = 0.0028), and sera of hyperthyroid patients with GD (P < 0.05) increased superoxide-specific 2-hydroxyethidium levels in HEK-293 TSHR cells after 48-hour incubation vs control subjects. In contrast, triiodothyronine (T3) did not affect reactive oxygen species (ROS) production. In primary thyrocytes, the 4-HNE marker was higher in patients with GD vs control subjects at 6 and 48 hours (P = 0.02 and P = 0.04, respectively). Further, after 48-hour incubation of HEK-293 TSHR cells with patient sera, 4-HNE was higher in patients with untreated GD compared with control subjects (P < 0.05). Conclusions: Monoclonal M22 and polyclonal serum TSAbs augment ROS generation and/or induce lipid peroxidation.

Performance and Specificity of 6 Immunoassays for TSH Receptor Antibodies: A Multicenter Study.

BACKGROUND: The measurement of TSH receptor (TSHR) antibodies is warranted for diagnosis of Graves' disease (GD). OBJECTIVE: The performance, detection sensitivity, and specificity of 6 TSHR immunoassays were compared. METHODS: Two bioassays and 4 binding assays (Kronus, Immulite, Kryptor, Dynex) were compared in a dilution study performed in patients with autoimmune thyroid disease. Both bioassays were compared to 2 binding assays using stimulatory (M22) and blocking (K1-70) monoclonal antibody (MAb) mixtures. RESULTS: Thirty samples from stimulatory (TSAb)-positive/blocking (TBAb)-negative patients with GD were diluted serially and measured in all assays. Samples were positive until dilution 1:2,187 in the TSAb bioassay, 1:81 in the Immulite (p < 0.002 vs. bioassay) and Kronus ELISA (p = 0.039) assays, and 1:27 in the Kryptor and Dynex ELISA (p < 0.001 vs. bioassay). Ten samples from TBAb-positive/TSAb-negative patients with GD or Hashimoto's thyroiditis were positive in all binding assays. None of the binding assays differentiated between TSAb and TBAb. Mixtures of 100% K1-70 (200 ng/mL), 80% K1-70 + 20% M22, 60% K1-70 + 40% M22, 40% K1-70 + 60% M22, 20% K1-70 + 80% M22, and 100% M22 (20 ng/mL) tested positive in both Immulite (26.4, 20.2, 15.2, 10.5, 6.3, 2.00 IU/L) and Kronus assays (27.1, 23.3, 19.3, 12.0, 5.7, 2.2 IU/L). These MAb mixtures were tested in the TBAb bioassay and showed 82, 61, 24 (negative), -26 (negative), -77 (negative), and -95% (negative) inhibition, respectively. CONCLUSIONS: The sample dilution study showed higher detection sensitivity for the TSAb bioassay, and the antibody mixture study demonstrated exclusive specificity of the bioassays over all automated and ELISA binding assays.

Analytical Performance and Validation of a Bioassay for Thyroid-Blocking Antibodies.

BACKGROUND AND OBJECTIVE: A cell-based bioassay for the measurement of thyroid blocking autoantibodies (TBAb) has been recently reported. The analytical performance and validation of this bioassay is assessed and described. METHODS: Chinese hamster ovary cells expressing a chimeric thyrotropin receptor were treated with bovine (b) TSH and different concentrations of an immunoglobulin G (IgG) monoclonal human TBAb (K1-70). TBAb was measured as a function of luciferase activity relative to bTSH alone and expressed as percent inhibition. Results obtained in the chimeric cell line were compared with those of a wild-type cell line. Analytical performance studies were subsequently performed with the chimeric cell line only. RESULTS: Immunodepletion of K1-70 IgG by using a protein G-Sepharose column showed that positive percent inhibition in the TBAb bioassay was detectable from K1-70 IgG only. The limit of blank was determined to be 12.2%. The limit of detection was 14% inhibition, equivalent to 0.4 ng/mL K1-70, while the limit of quantitation was 22% (coefficient of variation [CV] 12%) equivalent to 0.625 ng/mL K1-70. The dynamic range was between 14 ± 3.7 (mean % inhibition ± standard deviation) and 101 ± 2.6, equivalent to 0.4-10 ng/mL K1-70. The linear range was between 22 ± 2.6 and 93 ± 0.6 inhibition, equivalent to 0.625-5 ng/mL K1-70. The upper limit of the 99th percent reference range was 34% inhibition. In two laboratories, CV values for the intra- and inter-assay precisions for K1-70 ranged from 2% to 12% and from 1.7% to 14.5%, respectively. For patient sera, the CV values for the intra- and inter-assay precisions ranged from 3% to 9% and from 3% to 11%, respectively. No interference was found when follicle-stimulating hormone, luteinizing hormone, and human chorionic gonadotrophin were tested in the TBAb bioassay. The median of % inhibition values in 40 TBAb positive sera from patients with autoimmune thyroid disease were 93.5 (range 25-103) and 92 (range 64-107) for the wild type and chimeric cell lines, respectively. Further, all 40 samples of patients with various non-thyroidal autoimmune diseases were TBAb negative. CONCLUSIONS: This TBAb bioassay exhibits excellent analytical performance and high level of reproducibility.

Thyroid Stimulating Antibodies Are Highly Prevalent in Hashimoto's Thyroiditis and Associated Orbitopathy.

CONTEXT: Thyroid-associated orbitopathy (TAO) rarely occurs in patients with Hashimoto's thyroiditis (HT). OBJECTIVE: There is evidence that TSH receptor stimulating antibodies (TSAb) play a role in the pathogenesis of TAO. In this report, the prevalence of TSAb in HT patients with and without TAO was studied. DESIGN: This is a longitudinal observational study. SETTING: The study took place in an academic joint thyroid-eye clinic. SUBJECTS: A total of 1055 subjects were included. METHODS: TSAb was measured with a Food and Drug Administration-cleared bioassay that uses Chinese hamster ovary cells expressing a chimeric TSH receptor and a cAMP response element-dependent luciferase. Results of TSAb activity were reported as percentage of specimen-to-reference ratio (SRR%, cutoff >140%). MAIN OUTCOME MEASURE: We measured the association of TSAb with the risk of TAO in patients with HT. RESULTS: Of 700 consecutive and unselected patients with HT, 44 (6%) had overt TAO. Patients with HT+TAO were older (P < .001), heavier smokers (P = .032), and clustered less with autoimmune diseases (P = .005). All healthy controls were TSAb negative. In contrast, serum was TSAb positive in 30/44 (68.2%) and 36/656 (5.5%, P < .001) patients with HT+TAO and HT, respectively. Compared to patients with HT only, serum TSAb levels were higher in HT+TAO (median SRR%, 25th and 75th percentiles): 45, 35-65 vs 192.5, 115-455.3, P < .001. Highest TSAb values were noted in patients with active and severe TAO vs those with mild and inactive TAO: 486, 392-592 vs 142, 73-192.5; P < .001. The odds ratio of TSAb positivity for the risk of TAO adjusted for gender and age was 55.9 (95% confidence interval [CI], 24.6-127, P < .0001), whereas the odds ratio per 10-fold change in TSAb SRR% (quantitative TSAb) was 133 (95% CI, 45-390, P < .0001). The area under the receiver operating characteristic curve for qualitative and quantitative TSAb was 87.2% (95% CI, 80.6-93.8) and 89.4% (95% CI, 84.1-94.7), respectively. CONCLUSIONS: TSAb is strongly associated with TAO in HT and TSAb may contribute to the pathophysiology of TAO.

Standardization of a bioassay for thyrotropin receptor stimulating autoantibodies.

BACKGROUND: Cell-based bioassays for functional thyroid stimulating autoantibodies (TSAb) are sensitive diagnostic tools. However, there is no bioassay available that is standardized with international reference material. We aimed to promote the standardization of the test results among laboratories that perform TSAb bioassays and calibrate TSAb levels against the second international standard (IS) 08/204 from the National Institute for Biological Standards and Control (NIBSC). METHODS: Serum TSAb activity was measured with a FDA-cleared bioassay that utilizes CHO cells expressing a chimeric thyrotropin receptor (TSHR) and a c-AMP response-element-dependent luciferase. The IS was applied for calibration. TSAb results were reported as percentage of specimen-to-reference ratio (SRR%) and converted into mIU/L. RESULTS: The IS dose-response curve was obtained using concentrations from 0.3125 to 200 mIU/L. Mean TSAb SRR%±standard deviation (SD) values for the IS concentrations 0.3125, 0.625, 1.25, 2.5, 5, 10, 20, 40, 60, 80, 100, 120, 160, and 200 mIU/L were 63±4 (CV 6.3%), 63±4 (6.3), 67±2 (3.0), 76±6 (7.9), 91±8 (8), 134±8 (5.9), 201±13 (6.5), 294±12 (4.1), 336±10 (3.0), 348±8 (2.3), 360±14 (3.8), 371±15 (4.0), 381±9 (2.4), and 389±10 (2.6), respectively. A total of 127 dilution experiments were performed using 12 high TSAb-positive sera from patients with Graves' disease. When diluting TSAb-positive sera, IS concentrations within the linear range 5, 10, 20, 40, and 80 mIU/L were used for the calibration curve. All standard curves had R(2) values >0.95. Low coefficient of variation (CV %) values for the IS calibration curve (4-6%) were obtained. Compared to bovine TSH, no significant differences were noted using either a pool of healthy donors or a normal serum as reference controls. The average IU measured value for the assay cutoff (SRR 140%) corresponded to 9.54±1.68 mIU/L, and clinical application was shown in 60 Graves' patients. CONCLUSIONS: The TSAb bioassay demonstrated excellent performance in terms of linear range, limit of quantitation, and imprecision. The dilution experiments showed a high correlation coefficient and excellent reproducibility. Thus, TSAb levels can be reliably converted from SRR% to IU/L. These results offer the perspective of standardizing TSAb levels among laboratories and enable more accurate comparison of TSAb studies.

Analytical performance and clinical utility of a bioassay for thyroid-stimulating immunoglobulins.

The analytical performance and the clinical utility of a thyrotropin receptor (TSHR)-stimulating immunoglobulin (TSI) bioassay were compared with those of a TSHR-binding inhibitory immunoglobulin (TBII) assay. Limits of detection (LoD) and quantitation (LoQ), assay cutoff, and the half-maximal effective concentration (EC(50)) were measured. Dilution analysis was performed in sera of hyperthyroid patients with Graves disease (GD) during antithyroid treatment (ATD). Titer was defined as the first dilution step at which measurement of TSI or TBII fell below the assay cutoff. The LoD, LoQ, cutoff, and EC(50) of the bioassay were 251-, 298-, 814-, and 827-fold lower than for the TBII assay. There were 22%, 42%, 23%, and 14% more positive samples in the TSI bioassay at dilutions of 1:3, 1:9, 1:27, and 1:81 (P < .0001), respectively. Responders to ATD demonstrated marked differences in titers compared with nonresponders. The bioassay detected lower levels of TSHR autoantibodies, and the dilution analysis provided similar predictive values of both assays in GD.

Clinical relevance of thyroid-stimulating immunoglobulins in graves' ophthalmopathy.

PURPOSE: Thyroid-stimulating immunoglobulins (TSIs) likely mediate Graves' ophthalmopathy (GO). The clinical relevance of these functional autoantibodies was assessed in GO. DESIGN: Cross-sectional trial. PARTICIPANTS: A total of 108 untreated patients with GO. METHODS: Thyroid-stimulating immunoglobulins, assessed with a novel bioassay, bind to the thyrotropin receptor (TSHR) and transmit signals for cyclic adenosine monophosphate (cAMP)-dependent activation of luciferase gene expression. The cAMP/cAMP response element-binding protein/cAMP-regulatory element complex induces luciferase that is quantified after cell lysis. The TSI levels were correlated with activity and severity of GO and compared with a TSHR binding inhibitory immunoglobulin (TBII) assay. MAIN OUTCOME MEASURES: Thyroid-stimulating immunoglobulins, activity and severity of GO, diplopia, and TBII. RESULTS: Thyroid-stimulating immunoglobulins were detected in 106 of 108 patients (98%) with GO. All 53 hyperthyroid patients were TSI positive versus 47 patients (89%) who were TBII positive. All 69 patients with active GO were TSI positive, whereas only 58 of 69 patients (84%) were TBII positive. Thyroid-stimulating immunoglobulins correlated with the activity (r=0.83, P < 0.001) and severity (r=0.81, P < 0.001) of GO. All 59 patients with GO with diplopia were TSI positive, and 50 of 59 patients (85%) were TBII positive. Among patients with moderate-to-severe and mild GO, 75 of 75 (100%) and 31 of 33 (94%) were TSI positive compared with TBII positivity in 63 of 75 (84%) and 24 of 33 (73%), respectively. The TSI levels were higher in moderate-to-severe versus mild GO (489%±137% vs. 251%±100%, P < 0.001). Chemosis and GO activity predicted TSI levels alone (P < 0.001, multivariable analysis). The TSI levels were higher in patients with chemosis (527%±131%) than in patients without chemosis (313%±127%, P < 0.001). CONCLUSIONS: Thyroid-stimulating immunoglobulins show more significant association with clinical features of GO than TBII and may be regarded as functional biomarkers for GO. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

[Polymorphisms of MICA microsatellites in thyroidal autoimmunity]. / Polymorphismen des MICA-Mikrosatelliten bei thyreoidaler Autoimmunität.

BACKGROUND: The autoimmune thyropathies Graves' disease (GD) and Hashimoto's thyroiditis (HT) have multiple genetic and environmental backgrounds. Allele alterations of immune genes might contribute to the development of autoimmunity. PATIENTS AND METHODS: This study determined a triplet short tandem repeat (STR) polymorphism in the transmembrane region of the major histocompatibility complex (MHC) class I chain-related gene A (MICA) of 391 subjects (129 patients with GD, 56 patients with HT, and 206 healthy controls). Five common alleles have been reported for MICA. Genotypes were determined by fragment-length analysis in an ABI PRISM automatic sequencer. RESULTS: The prevalence of the MICA allele A9 was raised in patients with HT compared to controls (22.4% vs. 13.1%; p = 0.016; Fisher's exact test). For MICA, the genotype A5.1/A5.1 occurred more frequently in patients with GD than in controls (24.0% vs. 13.6%, odds ratio [OR] = 2.0, 95% confidence interval [95% CI] = 1.1-3.6; p = 0.018). The genotype MICA A6/A9 was decreased in patients with GD in contrast to controls (1.6% vs. 5.8%, OR = 0.2, 95% CI = 0.6-1.2; p = 0.089). Also, in patients with HT, the genotype A5.1/A9 was increased compared to controls (23.2% vs. 10.7%, OR = 2.5, 95% CI = 1.2-5.4; p = 0.025). CONCLUSION: The genotype MICA A5.1/A5.1 may be regarded as a risk factor for the development of GD. Also, the MICA genotype A5.1/A9 could raise the risk for acquiring HT. Finally, the genotype MICA A6/A9 could be seen as a protective factor against GD.