Use of Chinese hamster ovary cell lines transfected with cloned human thyrotropin receptor for the measurement of thyroid-stimulating antibodies: advantages and difficulties.
ABSTRACT We compared the activities of thyroid-stimulating antibodies (TSAb) as measured with two cell lines (JP26 and JP26/26) transfected with cloned human thyrotropin (TSH) receptor and the values for TSAb measured on human thyrocytes cultures. Sera were obtained from patients with Graves' disease, before, during and after therapy with carbimazole (1-methyl-2-thio-3-carbethoxyimidazole). The activities of TSAb performed with the three assays correlated significantly. The TSAb technique using JP26/26 cells was as sensitive as the method performed on human thyrocyte cultures since positive TSAb values were found in 45 out of 47 (95.7%) newly diagnosed patients, in 100% of patients who relapsed after drug withdrawal and in none in remission. When the JP26 cell line was used, sensitivity decreased as the detection rate was only 53.2 and 55.5% before treatment and in case of relapse, respectively. The TSH receptors analysis showed a receptor density two times higher for JP26/26 than for JP26. JP26/26 cells provide similar diagnostic information on human thyrocytes in patients with Graves' disease. Moreover with these cells, the procedure for cell culture is less cumbersome and precision is better. However, rigorous culture conditions are required to maintain TSH receptor expression in transfected cells.
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ABSTRACT: TSH receptor antibodies (TBII) in Graves' disease (GD) may be TSH receptor stimulating (TSAb) and blocking (TBAb) antibodies. In commercially available assays however, only total TBII titres can be measured, without discriminating between TSAb and TBAb. To design a TBII bioassay to detect of TSAb and to correlate TSAb activity with severity of hyperthyroidism in de novo GD patients. Thirty-five patients with de novo GD and 27 controls. The JP-26-26 cell line, which constitutively expresses the TSH receptor (TSHR), was stably transfected with a cyclic adenosine monophosphate responsive element--luciferase construct. The clone B1 exhibited a near linear increase in luminescence from 0.2 mU/l to 50 mU/l bovine TSH and was used as a TBII bioassay. TBII, free T4 and TSH were measured in the sera of all patients and controls. In the sera of 35 GD patients, TBII titres did not correlate with serum free T4 concentrations. In contrast, a strong and highly significant correlation was found between TSHR stimulating activity (luminescence) as measured with the TBII bioassay and serum free T4 levels (R = 0.80, P < 0.001). Interestingly, the luminescence/TBII ratio had a wide range at low TBII titres, whereas high TBII titres were associated with a low degree of TSHR activation. The TBII bioassay also detected TBAb in GD patients who spontaneously developed hypothyroidism. The B1-TBII-bioassay as developed in our laboratory has a high sensitivity for the detection of TSAb in GD and predicts the severity of hyperthyroidism in untreated GD patients. In addition, we found that high TBII titres are associated with weak TSHR activation.Clinical Endocrinology 05/2006; 64(4):429-35. · 3.40 Impact Factor
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ABSTRACT: Radioactive iodine therapy (RaI) in toxic multinodular goitre (TMNG) has been associated with the occurrence of Graves'-like hyperthyroidism. It has been postulated that pre-existing autoimmunity may contribute to this phenomenon. To study whether RaI induces thyrotropin receptor stimulating antibodies (TSAbs) in the short term in TMNG and whether pre-existing autoimmunity is relevant. Thirty-one patients with relapsing Graves' disease and 17 patients with TMNG, all eligible for RaI. Before and 6 weeks after RaI, sera were collected and analysed for the presence of thyroglobulin (Tg), thyroid peroxidase antibodies (TPO-Abs) and thyrotropin receptor binding antibodies (TBIIs). TSAbs were analysed with a novel high-sensitive luciferase-based bioassay based on the JP-26-26 cell line, which constitutively expresses the TSH receptor. In Graves' disease, RaI did not induce or increase the levels and proportion of patients with measurable levels of any of the antibodies measured, despite a significant increase in Tg. In contrast, in TMNG, RaI induced TBIIs in three TMNG patients, which was accompanied by measurable TSAbs on one occasion. We conclude from the present study that induction of TBIIs and TSAbs may occur shortly after RaI in TMNG and that pre-existing autoimmunity may not be a requirement for the induction of TBIIs, as evidenced by the lack of effect of RaI on TBIIs in Graves' disease.Nuclear Medicine Communications 03/2007; 28(2):123-7. · 1.38 Impact Factor
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ABSTRACT: Hyperthyroidism in Gravesˈdisease is attributable to the presence of TSH-receptor antibodies : thyroid stimulating antibodies (TSAb) and TSH binding inhibiting immunoglobulins (TBII). A new assay for TBII using a recombinant human receptor is now commercially available (Dynotest TRAK human, Brahms). We have evaluated its analytical and clinical performances in the diagnostic and in the follow-up of Gravesˈdisease. We have also compared them to those obtained for porcine TRAK (TRAK assay) and for TSAb measured on cellular cultures. We studied here 154 patients with Gravesˈdisease before and after treatment with antithyroid drugs (ATD). The performances of TBII assay with human TRAK were higher than those obtained for porcine TRAK and sometimes for TSAb. Thus TBII shoud be now measured with this commercially kit. Moreover, this new assay can advantageously replace TSAb measurement in the diagnosis and in the follow-up of Gravesˈpatients treated with ATD.Immuno-analyse & Biologie Specialisee - IMMUNO-ANAL BIOL SPEC. 01/2002; 17(1):26-32.