Assays of TSH-receptor antibodies in 576 patients with various thyroid disorders: their incidence, significance and clinical usefulness

The incidence and the significance of TSH-receptor antibodies in Graves' disease and in various thyroid disorders have been evaluated. TSH-binding inhibiting antibodies (TBIAb) and thyroid stimulating antibodies (TSAb) were detected in a large proportion of Graves' disease patients (TBIAb in 68.8% and TSAb in 77.8%), in a small number of patients with idiopathic myxoedema or Hashimoto's thyroiditis, and were not detected in patients with endemic euthyroid goitre, differentiated thyroid carcinoma and toxic adenoma. Furthermore, TSH-receptor antibodies were present in some patients with toxic multinodular goitre (TBIAb in 12.7% and TSAb in 15.9%). When TSH-receptor and other thyroid autoantibodies were compared, it was found that 13 of the 15 Graves' patients with negative tests for thyroglobulin and thyroid microsomal antibodies were positive for TSH-receptor antibodies. On the other hand, 9 of the 11 patients with toxic multinodular goitre who had positive TSH-receptor antibody tests, also had serum thyroglobulin and/or thyroid microsomal antibodies. No significant differences in the prevalence of TSH-receptor antibodies were found in Graves' patients irrespective of the presence of ophthalmopathy or pretibial myxoedema. Elevated TBIAb activity at the end of anti-thyroid drug treatment was found in 52.9% of Graves' patients who subsequently relapsed, while in Graves' patients in remission TBIAb was always negative. TSH-receptor antibody results were not predictive of the outcome of radioiodine treatment in Graves' disease. Finally no correlation could be found between TBIAb and TSAb in Graves' disease and Hashimoto's thyroiditis. In conclusion: the high incidence of TSH-receptor antibodies in Graves' disease confirms their pathogenetic role in the development of hyperthyroidism; TSH-receptor antibodies in Graves' disease are not significantly associated with the presence of ophthalmopathy or pretibial myxoedema; TSH-receptor antibody assays may be useful for the diagnosis of Graves' disease in the absence of other signs of autoimmunity. TBIAb seems to be a good predictor of relapse in Graves' patients treated with anti-thyroid drugs; a fraction of toxic multinodular goitre could be a nodular variant of Graves' disease.     

Autoantibodies highly increased in patients with thyroid dysfunction

To evaluate the significance of antithyroid antibodie levels, five hundred and twenty-six patients with thyroid diseases and 292 health subjects from Yuci district, Shanxi province, China, were studied. Serum levels were determined for thyroid hormone receptor antibody （TRAb）, microsomal antibody （TMAb） and thyroglobulin antibody （TGAb）. Among patients, the percentages for nodular goiter and thyroid adenoma, Graves＇ disease, and Hashimoto＇s thyroiditis are 44.1%, 19.6% and 17.7%, respectively. The ratios of female to male were 2.0 to 15.6. Antibody-positive patients for TMAb, TGAb and TRAb were detectable as 94.6%, 76.3% and 20.4% for Hashimoto＇s thyroiditis, and 40.0%, 30.0% and 90.3% for Graves＇s disease. In conclusion, the high levels of the TRAb in Graves＇ disease, and those of the TGAbFFMAb in Hashimoto＇s thyroiditis and idiopathic hypothyroidism are meaningful for characterizing the epidemiological basis of the diseases and for using as prognostic indicators for the relapse in individual patients. Cellular ＆ Molecular Immunology.     

Characterization of the natural killer cell activity in Hashimoto's and Graves' diseases

Natural killer (NK) cell activity and blood mononuclear cell subpopulations were characterized in patients with Hashimoto's thyroiditis ( n = 11), Graves' disease ( n = 20), non-toxic goitre ( n = 10) and in normal controls ( n = 22). NK cell activity against K 562 target cells and the capability of IFN-α, Il-2, and indomethacin to enhance NK cell activity in vitro did not differ significantly between the groups. The percentages of large granular lymphocytes, CD5 +, CD4 +, CD8 + and CD16 + cells were normal in patients with non-toxic goitre, Hashimoto's and Graves' diseases. There was no correlation between NK cell activities and TgAb, MAb and TSAb. Although NK cell activity is suppressed in several autoimmune diseases, NK cell function is normal in patients with autoimmune thyroid disorders.     

CD4~+CD25~+调节性T细胞在自身免疫性甲状腺疾病中数量和功能变化

目的:探讨自身免疫性甲状腺疾病患者外周血中CD4+CD25+调节性T细胞(Tregs)的数量和功能变化。方法:采用化学发光法测定20例初发Graves’病人、20例初发桥本甲状腺炎(HT)患者及20例健康体检者血清中促甲状腺素(TSH)、总三碘甲状腺原氨酸(TT3)、总甲状腺素(TT4)、甲状腺球蛋白抗体(TgAb)和甲状腺过氧化酶抗体(TPOAb)的水平;用流式细胞仪分析外周血单个核细胞(PBMC)中CD4+T细胞及CD4+CD25+Tregs的数量;采用磁珠分选技术分选5例HT病人和5例健康体检者PBMC中CD4+CD25+Tregs和CD4+CD25-T细胞,采用MTT法检测CD4+CD25+Tregs对自身CD4+CD25-T细胞增殖的抑制作用;提取各组PBMC的总RNA,经Real time-PCR检测TGFβ-1、Foxp3 mRNA的表达水平。结果:流式细胞检测结果显示,初发Graves’病人、初发HT患者外周血PBMC中CD4+T细胞数量与正常人比较无差异(P<0.05);初发HT患者外周血PBMC中CD4+CD25+Tregs占CD4+T细胞的比率为(1.55%±0.49%),明显低于正常对照组(2.86%±1.04%)(P<0.05);初发Graves’病人外周血PBMC中CD4+CD25+Tregs占CD4+T细胞的比率为(3.25%±0.97%),与正常对照组(2.86%±1.04%)相比无显著性差异(P<0.05)。MTT结果显示,初发HT患者CD4+CD25+Tregs对自身CD4+CD25-T细胞增殖的抑制百分率为15.7%±5.36%,与正常组(41.7%±9.87%)相比显著降低(P<0.05)。Real time-PCR结果显示,初发Graves’病人、初发HT患者PBMC的TGFβ-1 mRNA表达水平分别为(0.37±0.10)和(0.43±0.09),均明显低于正常对照组(1.02±0.04)(P<0.05);初发Graves’病人、初发HT患者PBMC的Foxp3 mRNA表达水平分别为0.62±0.09和0.42±0.29,均明显低于正常对照组(0.99±0.17)(P<0.05)。结论:本研究结果提示,HT患者外周血中CD4+CD25+Tregs的数量和功能明显降低。Graves’病和HT患者外周血PBMC中TGFβ-1、Foxp3 mRNA表达水平明显降低。     

Discrepancy between Haemagglutination and Radioimmunological Techniques for Measurement of Serum Thyroglobulin Autoantibodies

Recently, it has been suggested that in some patients with autoimmune thyroid diseases the tanned red cell (TRC) method for detection of thyroglobulin autoantibodies (TgAb) is negative where TgAb measured by radioimmunoassay (RIA) show positive values. To investigate this further, patients with thyroid diseases, pernicious anaemia and a control group were studied for serum concentrations of TgAb by TRC and by quantitative RIA, calibrated against MRC Standard A65/93. Antibodies for microsomes (MAb) were measured immunofluoretically. There was in all patient groups (Hashimoto's thyroiditis (n = 41), Graves' disease (n = 50), idiopathic myxoedema (n = 12), euthyroid Graves' disease (n = 7), pernicious anaemia (n = 81) a discrepancy between TgAb measured by TRC and RIA, respectively, whereas there was a reasonable correlation between the presence of TgAb by RIA and the presence of MAb. A possible interference from antinuclear antibodies and rheumatoid factors was ruled out. There was no increased frequency of TgAb measured by RIA in the control group. Fractionation of TRC negative sera revealed macromolecular TRC-activity, whereas TgAb positive sera by both methods had almost exclusively RIA and TRC activity corresponding to IgG. Based on these results and others it seems that the TRC method for measurement of serum TgAb is of limited diagnostic value. Furthermore, the TRC method is in many cases not sensitive enough for screening for TgAb prior to measurement of serum Tg, which is of importance as this method shows false values in the presence of TgAb due to methodological interference.     

Heterogeneity of thyroid autoantigens identified by immunoblotting

Autoimmune thyroid disease in man is commonly associated with autoantibodies against thyroglobulin, microsomes, and the TSH receptor, and the character and specificity of these antithyroid antibodies have been extensively utilized in investigating these conditions. In the present study we have asked whether other thyroid-related antigens exist, against which autoantibodies may be directed. A crude thyroid extract was separated by polyacrylamide gel electrophoresis followed by immunoblotting with serum obtained from patients with Graves' disease or Hashimoto's thyroiditis. Antibodies in sera from patients with Graves' disease and Hashimoto's thyroiditis reacted with many antigenic determinants in immunoblots of the thyroid membrane preparation (2000g supernatant). These determinants were disease specific in that sera from normals and patients with Addison's disease and rheumatoid arthritis did not react, but there was no difference between the patterns of reactivity with Graves' disease or Hashimoto's thyroiditis sera. Thyroglobulin produced two predominant bands of reactivity at 320 and 200 kDa, whereas purified microsomal antigen produced a triplet of bands around 105 kDa, when these preparations were reacted with appropriate autoimmune sera. Nonetheless, some sera produced additional bands with the microsomal antigen blots, indicating that some of the antigens which were detected using crude thyroid membrane remained in the microsome preparation to produce multiple antibody binding reactivities. We were unable to inhibit any of the antibody binding with TSH. Purification of individual thyroid antigens on the basis of their molecular weights should standardize current antibody assays and permit more detailed evaluation of the cellular immune responses in Graves' disease and Hashimoto's thyroiditis.     

Heterogeneity of immunoregulatory T cells in human thyroid autoimmunity: influence of thyroid status.

Monoclonal antibodies of the OKT series were used to identify circulating T lymphocytes (OKT3+), their helper-inducer (OKT4+) and suppressor-cytotoxic (OKT8+) subsets and cells bearing Ia antigen (OKIa+) in 75 patients with thyroid autoimmune disorders, including 14 Graves' disease, 21 myxoedema, 20 asymptomatic thyroiditis, 12 Hashimoto's thyroiditis and eight simple goitre with superimposed thyroiditis. In the whole population of patients, a negative correlation was observed between the percentage of OKT8+ cells and serum free thyroxine levels whatever the type of thyroiditis. The percentage of OKT8+ cells was decreased in Graves' disease and increased in myxoedema while it reversed after adequate treatment of the two diseases. However, a trend to a decrease in the proportion of OKT8+ cells was still observed in treated Graves' disease and in all the other groups of thyroiditis with euthyroidism. The minor modifications observed for OKT3+ and OKT4+ cells were in relation with those of OKT8+ cells. There was an increased percentage of Ia+ cells in Graves' disease and in Hashimoto's thyroiditis partly reflecting the presence of activated lymphocytes. In conclusion, these data suggest first of all a direct influence of serum T4 on the distribution of circulating OKT8+ cells in addition to documenting the heterogeneity of T cell immunoregulatory factors.     

Modulation of Fas-mediated apoptosis of human thyroid epithelial cells by IgG from patients with Graves' disease (GD) and idiopathic myxoedema

The expression of two autoimmune thyroid diseases, GD and idiopathic myxoedema, is associated with antibodies to the thyroid-stimulating hormone (TSH) receptor. Thyroid stimulating antibodies (TSAb) in GD are TSH agonists and cause hyperthyroidism as well as goitre, whereas thyroid stimulation blocking antibodies (TSBAb) in idiopathic myxoedema are TSH antagonists and cause hypothyroidism and thyroid atrophy. We investigated the effect of antibodies to TSH receptor on Fas-mediated apoptosis of thyroid epithelial cells (thyrocytes). Human IgG was isolated from healthy donors, patients with GD and idiopathic myxoedema. Human thyrocytes were obtained from surgical specimens. Thyrocytes were cultured in the presence or absence of human IgG with or without interferon-gamma (IFN-γ) or IL-1β for a specified time. After incubation, we examined the level of cAMP in cultured supernatants and both Fas and Bcl-2 expression on thyrocytes. In addition, we examined anti-Fas-mediated apoptosis of thyrocytes. Fas expression on thyrocytes was significantly down-regulated by Graves' IgG and TSH, although idiopathic myxoedema IgG did not affect Fas expression on thyrocytes. Idiopathic myxoedema IgG abrogated the effect of TSH on both cAMP production and inhibition of Fas expression on thyrocytes. Treatment of thyrocytes with IL-1β or IFN-γ caused a marked augmentation of Fas expression on thyrocytes. The increase of Fas expression of thyrocytes induced by IL-1β or IFN-γ was significantly suppressed in the presence of TSH or Graves' IgG. Anti-Fas-induced apoptosis of thyrocytes was observed in thyrocytes treated with IL-1β or IFN-γ, but was markedly inhibited in the presence of TSH or Graves' IgG. Furthermore, idiopathic myxoedema IgG abrogated most of the inhibitory effect of TSH on Fas-mediated apoptosis of thyrocytes treated with IL-1β or IFN-γ. Bcl-2 expression of thyrocytes did not change after stimulation with TSH, Graves' IgG, idiopathic myxoedema IgG, IL-1β or IFN-γ. These results suggest that TSAb found in Graves' patients may be potentially involved in the development of goitre by inhibition of Fas-mediated apoptosis of thyrocytes. In addition, TSBAb inhibit the action of TSH and increase the sensitivity toward Fas-mediated apoptosis of thyrocytes, inducing thyroid atrophy seen in patients with idiopathic myxoedema.     

Thyroid antibodies are produced by thyroid-derived lymphocytes.

The significance of the characteristic lymphocytic infiltrate in the target organ in organ-specific autoimmune disease is unknown. We have demonstrated the production of thyroglobulin antibodies and immunoglobulins (IgG, IgM and IgA) by thyroid-derived lymphocytes in Graves' disease and Hashimoto's thyroiditis two plaque forming cell (PFC) assays. The thyroid appears to be an important site of thyroglobulin antibody production but the thyroid lymphocytes also contain many IgG PFCs of non-thyroglobulin specificity. Short-term culture and direct thyroglobulin antibody assay on micro-ELISA plates confirmed the results of the PFC assay. Therapies such as carbimazole may therefore be acting on a localized source of autoantibody production.     

Serum immunoglobulin levels in thyroid disease

Serum levels of IgG, IgA and IgM were assayed by radial immunodiffusion in 261 patients with eight categories of thyroid disease. These composed eighty-three patients with a first episode of untreated active Graves' disease (toxic diffuse goitre), ten with relapsed Graves' disease, seventeen with thyrotoxicosis due to a multinodular goitre, forty-nine with Hashimoto's thyroiditis, twenty-eight with primary (non-goitrous) myxoedema, forty with non-toxic goitre, eighteen with an adenoma and sixteen with euthyroid ophthalmopathy.

Eighteen (21·7%) patients with a first episode of Graves' disease had abnormally high IgG levels whereas eight (80%) of those who had relapsed after a course of Carbimazole had high levels. Those Graves' disease patients with raised IgG levels had a significantly higher 24-hr radioiodine uptake than those with normal levels. Eight (16·3%) patients with Hashimoto's thyroiditis had abnormally high levels of IgG associated with a higher incidence of thyroglobulin autoantibodies. Very few (<6%) patients with primary myxoedema, non-toxic goitre and adenoma had abnormal levels. Euthyroid patients with ophthalmopathy had a significantly lower mean IgG level than the corresponding mean level found in the group with active Graves' disease.

However, despite the differences between groups described above, there were no significant differences of mean IgG, IgA and IgM levels in seven of the eight groups when compared with normal subjects. Only the group with relapsed Graves' disease had a significantly higher mean IgG. None of the patients studied had abnormal IgM or IgA levels.

     

Antibodies that promote thyroid growth. A distinct population of thyroid-stimulating autoantibodies

We used a strain of differentiated rat-thyroid cells in continuous culture (the FRTL-5 strain) to detect the presence of growth-promoting antibodies in serum samples from patients with autoimmune thyroid disease. We found that IgG preparations from 17 of 20 patients (85 per cent) with active Graves' disease and two of five patients (40 per cent) with Hashimoto's thyroiditis could augment thyroid-cell growth. In parallel with IgG-induced elevations in intracellular cyclic AMP levels in the same cell line, all 20 of the patients with active Graves' disease had thyroid-stimulatory antibodies. Patients' IgG preparations fell into three subclasses: those with both potent cyclic AMP stimulation and potent growth-promoting activity; those with potent cyclic AMP stimulation but low-level growth promotion; and those with potent growth promotion and low-level cyclic AMP action. Growth-promoting antibodies were not detected in patients with Graves' disease in remission (seven patients), nodular goiter (seven), subacute thyroiditis (five), or atrophic thyroiditis (one). Simultaneous assays of growth promotion and cyclic AMP stimulation may be useful in the care of patients with autoimmune thyroid disease.     

Review of thyroid disease and recent progress in thyroid research

Major thyroid diseases and recent progress in thyroid research are reviewed, including our clinical experiences and data on genetic analysis. Of the 19,944 patients receiving care in our endocrinology and metabolism department over the past 26 years(from 1974 to 2000), there were 4,471(22.4%) patients with thyroid diseases. Of these patients with thyroid disease, 37.3% had Graves' disease, 24.1% had Hashimoto's thyroiditis, and 22.2% had a benign thyroid tumor. Male-to-female ratio for Graves' disease was 1:3.2. The precise mechanism and genetic or environmental factors underlying the onset and progression of autoimmune thyroid disease need further investigation, although recent thyroid research, especially molecular level studies, has resulted in many new insights. Our genetic analysis of patients and experimental animals with thyroglobulin(Tg) abnormalities indicated the amino acids involved in the surface electric charge were important in maintaining the solid structure of Tg and thyroid hormone synthesis in addition to tyrosine and cysteine. In three patients with hyperthyroid Graves' disease, Hashimoto's thyroiditis or idiopathic hypothyroidism, followed by the author for 8 to 20 years, it was indicated that continued comprehensive care was needed for various episodes, even those arising from non-endocrine conditions, throughout the clinical course, although clinical and laboratory findings showed improvement of the thyroid disease itself.     

Clinical value of a bispecific antibody binding to thyroglobulin and thyroperoxidase (TGPO-aAb) in various thyroid diseases.

TGPO-aAb is a bispecific antibody which binds to thyroglobulin as well as thyroid peroxidase. It is supposed to be raised in some patients with autoimmune thyroid disease. We investigated 205 patients suffering from Graves' disease (n = 81), Hashimoto's thyroiditis (n = 36), toxic nodular goitre (n = 50), differentiated carcinoma of the thyroid (n = 10), and autoimmune thyropathy of unknown origin (n = 28). An immunoradiometric assay was used to measure serum TGPO-aAb. Eighty-nine of 205 patients had elevated titres of TGPO-aAb. If TGPO-aAb were raised then autoantibodies against thyroglobulin and thyroid peroxidase were always raised, too. This was, however, not true vice versa. We found TGPO-aAb in 61% of patients with Hashimoto's, 49% of patients with Graves', 64% of patients with autoimmune thyropathy, but only in 12% of patients with toxic nodular goitre. In patients with thyroid carcinoma TGPO-aAb was found only if there was evidence of paraneoplastic autoimmune thyroiditis. We re-examined 16 of 36 patients with Hashimoto's thyroiditis after 1 year: 8 patients had retained their raised TGPO-aAb, 4 patients showed no TGPO-aAb on both occasions, and 4 patients had 'lost' their previously raised TGPO-aAb on follow-up. We conclude that TGPO-aAb may provide additional information in Hashimoto's thyroiditis. Determination of TGPO-aAb does not allow to distinguish between various forms of autoimmune thyroid disease. Nevertheless, the presence of TGPO-aAb and its variation during the natural course of autoimmune thyroid disease remains to be understood which would give a better insight into its clinical significance.     

Autoantibodies in autoimmune thyroid disease promote immune complex formation with self antigens and increase B cell and CD4+ T cell proliferation in response to self antigens

B cells are centrally involved as antigen-presenting cells in certain autoimmune diseases. To establish whether autoantibodies form immune complexes (IC) with self-antigens in autoimmune thyroid disease (AITD) and promote B cell uptake of self-antigen, sera from patients with Hashimoto's thyroiditis (HT), Graves' disease (GD) and healthy controls were incubated with human thyroglobulin (Tg) before adding normal peripheral blood mononuclear cells. The deposition of immunoglobulins and C3 fragments on B cells was then assessed. Inclusion of Tg in serum from HT patients promoted B cell capture of IgG and C3 fragments. Furthermore, the binding of Tg to B cells in preparations of normal blood cells was higher in HT serum than in serum from controls and correlated positively with the serum anti-Tg activity, as did the B and CD4+ T cell proliferation. Disruption of the three-dimensional structure of Tg by boiling reduced the proliferative responses. The data indicate that anti-Tg antibodies associated with AITD facilitate the formation of complement-activating Tg/anti-Tg complexes, binding of IC to B cells, and the subsequent proliferation of B and T cell subsets. This represents a novel mechanism for the maintenance of autoimmune processes in AITD and links autoreactive T cell responses with the presence of autoantibodies.     

自身免疫甲状腺病患者血清中IL-12和IL-18水平的分析

目的:提供自身免疫甲状腺病(AITD)患者体内Th1/Th2平衡紊乱的依据。方法:应用酶联免疫吸附法(ELISA)测定27例Graves病(GD)、24例甲状腺功能正常的桥本甲状腺炎(HT)、25例甲状腺功能低下的HT患者及20例正常对照者血清中IL12和IL18的浓度,并检测GD患者的甲状腺刺激性抗体。结果:GD患者与甲状腺功能正常的HT患者血中IL12、IL18水平无明显差异,但均高于正常对照者的相应水平。甲状腺功能低下的HT患者血中IL12和IL18的水平与正常对照者无差异。在GD和甲功正常的HT,IL18与IL12呈明显正相关。在GD,IL12和IL18均与其甲状腺刺激性抗体(TSAb)活性呈正相关。在甲状腺功能正常的HT还存在IL12和IL18二者与甲状腺球蛋白抗体(TgAb)的显著性正相关。结论:提示Th1型细胞在GD和HT两种AITD的发病中均起重要作用。通过抑制Th2型免疫反应,促进向Th1型的转变来治疗GD时,有可能导致病情恶化。     

Thyroid Stimulating Antibodies, Thyroglobulin Antibodies and Serum Proteins during Treatment of Graves'' Disease with Radioiodine or Propylthouracil

The relation between serum concentrations of thyroglobulin antibodies (TgAb), thyroid-stimulating antibodies (TSAb) and serum immunoglobulins during treatment of Graves' disease was studied in 36 consecutive patients treated randomly with 131-iodine (n = 16) or propylthiouracil (n = 20). The patients were investigated before treatment was started and on seven occasions within the following year. In the entire patient group 78% were positive for TSAb and 47% for TgAb. There was a significant correlation between TSAb and TgAb in 15 patients concomitantly positive. There were no significant changes in serum immunoglobulins during treatment in either group of patients. In the radioiodine-treated group of patients TgAb was reduced after 1 week, whereas TSAb showed insignificant variations. After 5-10 weeks both antibodies increased, for TgAb with a median peak level 3 time above the initial concentration. Of 16 patients treated with radioiodine five developed myxoedema and four of these were positive for TgAb. There was a relation between the development of myxoedema and the ratio between increases of TSAb and TgAb. Increase in TSAb was not related to serum thyroglobulin (Tg) measured in TgAb-negative patients. Propylthiouracil showed minor effects on the studied variables, but with lower mean values of Tg, TgAb and TSAb at the end of the observation period. The results indicate an immunological relation between TSAb and TgAb, although differences between their course exist in some situations.     

Structural features of the autoantigens involved in thyroid autoimmune disease: the thyroid microsomal/microvillar antigen

The microsomal/microvillar antigen of the human thyroid gland which provokes thyroid autoimmunity was characterised by immunoprecipitation studies. Sera from patients with Hashimoto's thyroiditis, primary myxoedema or Graves' disease containing autoanti-microsomal antibody specifically precipitated a component, which under reducing conditions migrates with a mol. wt of 105,000 on SDS-polyacrylamide gel electrophoresis. This protein was absent in auto- or xeno-anti-thyroglobulin precipitates, which under reducing conditions display four polypeptides of Mr 260,000, 230,000, 180,000 and 142,000. Under non-reducing conditions, the microsomal/microvillar antigen displayed a small shift in mobility to a mol. wt of 117,000 suggesting the presence of intrachain disulphide bonds. In contrast, under these conditions, anti-thyroglobulin precipitated components displaying polypeptides of approx. mol. wts in the region of 240,000-260,000, 170,000-180,000 and 140,000. Absorption of thyroiditis sera on thyroglobulin-Sepharose followed by immunoprecipitation abolished the anti-thyroglobulin components without affecting the binding of the 105,000-dalton polypeptide, if the sera contained antimicrosomal antibody. No comparable material was identified in microsomal membrane preparations prepared from the stomach which is also commonly involved in organ-specific autoimmunity. The 105,000-dalton component does not bind to a Lens culinaris lectin affinity column. We conclude that the epitopes of the microsomal/microvillar antigen are presented on a poorly glycosylated peptide of mol. wt 105,000, which is probably stabilised by intrachain disulphide bonds and which does not share serological reactivity with membrane-bound thyroglobulin.     

IgA class and subclass thyroid auto-antibodies in Graves' disease and Hashimoto's thyroiditis

The reported prevalence of IgA class thyroid antibodies in Hashimoto's thyroiditis is variable and the IgA subclass distribution in unknown, despite recent reports of IgG subclass restriction in the thyroid auto-antibody response. Using an ELISA, IgA class antibodies were found against thyroglobulin (Tg) and microsomes (Mic) in 40-52% of patients with Graves' disease and Hashimoto's thyroiditis, and, against thyroglobulin, they were detected in the absence of IgG antibodies in 10% of the cases. Both IgA1 and IgA2 subclasses were detected in all patients with IgA class antibodies, although a significantly higher proportion of IgA2 relative to IgA1 was found in microsomal compared with thyroglobulin antibodies. In view of the high turnover rate and unique complement-fixing properties of IgA2 antibodies, this class of thyroid auto-antibody may play an important role in determining the response in thyroid auto-immunity.     

Detection of interleukin-6 and interleukin-1 production in human thyroid epithelial cells by non-radioactive in situ hybridization and immunohistochemical methods.

Human endocrine thyroid epithelial cells have been described to produce cytokines in vitro. In order to determine whether they do so in vivo during thyroiditis, parallel studies on mRNA expression with a non-radioactive in situ hybridization technique and immunohistochemical detection for the protein were performed on frozen sections of thyroid samples from autoimmune thyroiditis (Graves' disease and Hashimoto's thyroiditis), non-toxic goitre and normal thyroid tissue. cDNA probes were sulphonated and their hybridization with mRNA was detected with a sulphonyl-specific monoclonal antibody. This signal was amplified and visualized with the alkaline phosphatase-anti-alkaline phosphatase (APAAP) system. The protein products were detected with immuno-purified rabbit F(ab')2 antibody fragments recognizing recombinant human cytokines, visualized by the immunoperoxidase technique. Each sample was studied at the two levels. Both interleukin-6 mRNA and protein were found in the endocrine cells. There was no obvious difference between autoimmune thyroiditis and non-toxic goitre. However, normal thyroid epithelial cells produced less interleukin-6. Interleukin-1 alpha mRNA and its protein were found in epithelial cells from Hashimoto's thyroiditis samples, but not in the others, except one Graves' disease sample, in which only mRNA was detected. Interleukin-1 beta was not detected in these cells, its mRNA was only found in one of the Graves' disease samples. These cytokines were also detected in some infiltrating cells.     

Thyroid function tests

About 80% of thyroid disease consists of thyroid-specific autoimmune diseases, Hashimoto's disease and Grave's disease. To diagnose thyroid diseases, testings for (1) thyroid function and (2) pathogenetic autoantibodies are indispensable. To assess thyroid function, serum hormone concentrations, such as TSH, FT4 and FT3 are measured. Among these hormones, serum TSH concentrations are the most reliable and informative regarding thyroid function, correcting indicating a hyperthyroid, euthyroid or hypothyroid state. Therefore, TSH measurement appears to be the first choice in selecting the hormone determination. Reference intervals for normal healthy subjects of TSH are around 0.4-5.0 microU/ml. The second choice for thyroid function assessment are FT4 which supersedes total T4(TT4). TT4 is affected by changes in serum thyroid hormone binding proteins(TBG, TTR, Albumin). For example, euthyroid pregnant women whose serum TBG are physiologically higher than those of non-pregnant women show augmentation of TT4. However, FT4 depicts within reference intervals, although measurement of FT4 alone is unable to detect any abnormality of thyroid hormone binding proteins. According to its plasma concentration and binding affinity, FT3 measurement deserves no more significance than T3. Another important test for thyroid diseases is to detect serum autoantibodies against thyroid tissues, such as TgAb, TPOAb. Much more important is TSH receptor antibody which differentiates Graves' disease from Hashimoto's thyroiditis. In patients who show hyperthyroidism and some very uncommon hypothyroidism, TSH receptor antibodies should be measured. Three indicators are available as routine tests; TRAb measured by radioreceptor assay; TSAb determined by bioassay using cultured porcine thyroid cells. Usually, TRAb activity clinically correlates well with TSAb. TSBAb was initially discovered in patients with severe hypothyroidism with atrophic thyroid gland. TSBAb blocks thyroid stimulating activity of TSH and consequently causes severe hypothyroidism. TRAb and TSAb are very useful to diagnose and follow patients with Grave's disease.