Preconception management of thyroid dysfunction

Uncorrected thyroid dysfunction in pregnancy has well-recognized deleterious effects on foetal and maternal health. The early gestation period is one of the critical foetal vulnerability during which maternal thyroid dysfunction may have lasting repercussions. Accordingly, a pragmatic preconception strategy is key for ensuring optimal thyroid disease outcomes in pregnancy. Preconception planning in women with hypothyroidism should pre-empt and mirror the adaptive changes in the thyroid gland by careful levothyroxine dose adjustments to ensure adequate foetal thyroid hormone delivery in pregnancy. In hyperthyroidism, the goal of preconception therapy is to control hyperthyroidism while curtailing the unwanted side effects of foetal and maternal exposure to antithyroid drugs. Thus, pregnancy should be deferred until a stable euthyroid state is achieved, and definitive therapy with radioiodine or surgery should be considered in women with Graves' disease planning future pregnancy. Women with active disease who are imminently trying to conceive should be switched to propylthiouracil either preconception or at conception in order to minimize the risk of birth defects from carbimazole or methimazole exposure. Optimal strategies for women with borderline states of thyroid dysfunction namely subclinical hypothyroidism, isolated hypothyroxinaemia and thyroid autoimmunity remain uncertain due to the dearth of controlled interventional trials. Future trial designs should aspire to recruit and initiate therapy before conception or as early as possible in pregnancy.

Strumal Carcinoid of the Ovary: An Immunohistochemical and Electron Microscopic Study

A case of strumal carcinoid of the ovary is reported. The follicles contained T4-immunoreactive substance, whereas the carcinoid component of the tumor had a trabecular structure and showed argyrophilic elements. Pancreatic-polypeptide and enteroglucagon were localized in these cells by an immunocytochemical method. The same cells displayed small electrondense endocrine-like granules. A common precursor for the thyroid and carcinoid components is postulated.

Occupational pesticide exposure and subclinical hypothyroidism among male pesticide applicators

OBJECTIVES

Animal studies suggest that exposure to pesticides may alter thyroid function; however, few epidemiologic studies have examined this association. We evaluated the relationship between individual pesticides and thyroid function in 679 men enrolled in a substudy of the Agricultural Health Study, a cohort of licensed pesticide applicators.

METHODS

Self-reported lifetime pesticide use was obtained at cohort enrolment (1993-1997). Intensity-weighted lifetime days were computed for 33 pesticides, which adjusts cumulative days of pesticide use for factors that modify exposure (eg, use of personal protective equipment). Thyroid-stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3) and antithyroid peroxidase (anti-TPO) autoantibodies were measured in serum collected in 2010-2013. We used multivariate logistic regression to estimate ORs and 95% CIs for subclinical hypothyroidism (TSH >4.5 mIU/L) compared with normal TSH (0.4-<4.5 mIU/L) and for anti-TPO positivity. We also examined pesticide associations with TSH, T4 and T3 in multivariate linear regression models.

RESULTS

Higher exposure to the insecticide aldrin (third and fourth quartiles of intensity-weighted days vs no exposure) was positively associated with subclinical hypothyroidism (ORQ3=4.15, 95% CI 1.56 to 11.01, ORQ4=4.76, 95% CI 1.53 to 14.82, ptrend <0.01), higher TSH (ptrend=0.01) and lower T4 (ptrend=0.04). Higher exposure to the herbicide pendimethalin was associated with subclinical hypothyroidism (fourth quartile vs no exposure: ORQ4=2.78, 95% CI 1.30 to 5.95, ptrend=0.02), higher TSH (ptrend=0.04) and anti-TPO positivity (ptrend=0.01). The fumigant methyl bromide was inversely associated with TSH (ptrend=0.02) and positively associated with T4 (ptrend=0.01).

CONCLUSIONS

Our results suggest that long-term exposure to aldrin, pendimethalin and methyl bromide may alter thyroid function among male pesticide applicators.

Increased leptin levels correlate with thyroid autoantibodies in nonobese males

OBJECTIVE

Leptin is an adipokine that regulates body weight and appetite. It is also an inflammatory cytokine that influences immune reactivity and autoimmunity. Leptin levels are increased in obesity and are higher in women than in men. We aimed to determine whether leptin levels, independent of sex and body mass index (BMI), are associated with thyroid autoimmunity.

DESIGN

This study uses data from The Third National Health and Nutrition Examination Survey (NHANES III) to test the association of leptin and thyroid autoimmunity, independent of BMI.

MEASUREMENTS

Thyroid-stimulating hormone, thyroxine, antithyroid peroxidase (TPO) antibodies and leptin levels were measured in 2902 men and 3280 women within the NHANES III population. BMI was calculated from height and weight.

RESULTS

Women had significantly higher leptin levels and anti-TPO antibody titres than men. Correlation analyses demonstrated that leptin levels were associated with anti-TPO antibody levels in the total population, but when men and women were analysed separately, this association was lost. We then stratified men and women into obese (BMI > 30) or nonobese (BMI ≤ 30) subgroups and determined the association between leptin levels and anti-TPO antibody titres for each subgroup. Using regression analysis, we found that increased leptin levels correlated with thyroid autoantibodies in nonobese males, but not in obese males or in females.

CONCLUSIONS

Leptin levels correlated with thyroid autoantibody titres in nonobese males. This association was not found in females. Sex and body habitus should therefore be considered in studying the role of leptin in other autoimmune conditions.

Hypothyroxinemia and TPO-antibody positivity are risk factors for premature delivery: the generation R study

CONTEXT

Premature delivery is an important risk factor for child mortality and psychiatric, metabolic, and cardiovascular disease later in life. In the majority of cases, the cause of prematurity cannot be identified. Currently, it remains controversial whether abnormal maternal thyroid function during pregnancy increases the risk of premature delivery. Therefore, we investigated the relation between maternal serum thyroid parameters and the risk of premature delivery in a large prospective population-based study.

DESIGN

Serum TSH, free T4 (FT4), T4, and TPO antibodies (TPOAbs) were determined during early pregnancy in 5971 pregnant women from the Generation R study. Data were available on maternal age, parity, smoking, socioeconomic status, ethnicity, maternal anthropometrics, and urinary iodine levels.

RESULTS

Of all women, 5.0% had a premature delivery (<37 weeks), 4.4% had a spontaneous premature delivery, and 1.4% had a very premature delivery (<34 weeks). High TSH levels and subclinical hypothyroidism were associated with premature delivery but not with spontaneous premature delivery. Maternal hypothyroxinemia was associated with a 2.5-fold increased risk of premature delivery, a 3.4-fold increased risk of spontaneous premature delivery, and a 3.6-fold increased risk of very premature delivery (all P < .01). TPOAb positivity was associated with a 1.7-fold increased risk of premature delivery (P = .01), a 2.1-fold increased risk of spontaneous premature delivery (P = .02), and a 2.5-fold increased risk of very premature delivery (P = .04). These effects remained similar after correction for TSH and FT4 levels.

CONCLUSIONS

Hypothyroxinemia and TPOAb positivity are associated with an increased risk of premature delivery. The increased risk in TPOAb-positive women seems to be independent of thyroid function.

A high frequency of circulating th22 and th17 cells in patients with new onset graves' disease

T-helper (Th) 22 and Th17 cells are involved in the pathogenesis of autoimmune diseases. However, their roles in the pathogenesis of Graves'disease (GD) are unclear. This study is aimed at examining the frequency of peripheral blood Th22, Th17, and Th1 cells and the levels of plasma IL-22, IL-17, and IFN-γ in patients with GD. A total of 27 patients with new onset GD and 27 gender- and age-matched healthy controls (HC) were examined for the frequency of peripheral blood Th22, Th17, and IFN-γ cells by flow cytometry. The concentrations of plasma IL-22, IL-17, and IFN-γ were examined by enzyme-linked immunosorbent assay. The levels of serum TSHR antibodies (A-TSHR), free triiodothyronine (FT3), free thyroxine (FT4), and thyroid stimulating hormone (TSH) were examined by radioimmunoassay and chemiluminescent assay, respectively. The levels of serum TSAb were examined by enzyme-linked immunosorbent assay. In comparison with those in the HC, significantly elevated percentages of Th22 and Th17 cells, but not Th1 cells, and increased levels of plasma IL-22 and IL-17, but not IFN-γ, were detected in GD patients (P<0.0001, for both). The percentages of both Th22 and Th17 cells and the levels of plasma IL-22 and IL-17 were correlated positively with the levels of serum TSAb in GD patients (r = 0.7944, P<0.0001; r = 0.8110, P<0.0001; r = 0.7101, p<0.0001; r = 0.7407, p<0.0001, respectively). Th22 and Th17 cells may contribute to the pathogenesis of GD.

[Is polycystic ovary syndrome associated with autoimmune thyroiditis?]

INTRODUCTION

Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies in women of fertile age and lately there is a discussion about its possible association with autoimmune diseases. The aim of the study was to examine incidence of autoimmune thyreoiditis (AIT) in PCOS women.

PATIENTS AND METHODS

64 PCOS patients were enrolled and 68 healthy menstruating women served as controls. All subjects were examined for thyrotropin (TSH), free thyroxin (fT4) and the presence as well as titers of antithyroid antibodies aTG (anti-thyreoglobulin) and aTPO (anti-thyreoperoxidase).

RESULTS

There was no difference between PCOS and controls in average TSH levels (2.37 ± 1.46 mIU/l vs 2.37 ± 1.46 mIU/l) (p = 0.953), and fT4 levels (16.36 ± 5.34 pmol/l vs 16.49 ± 2.32 pmol/l) (p = 0.852). Autoantibodies titers were also non-significant aTG (53.09 ± 157.07 IU/ml vs 29.8 ± 100.77 IU/ml, p = 0.386) and aTPO (59.74 ± 149.03 IU/ml vs 45 ± 204.77 IU/ml, p = 0.805). However, PCOS women had significantly higher prevalence of aTPO (18.75 vs 7.35%, p = 0.045). On the other hand, the overall prevalence of AIT was similar in both groups.

CONCLUSION

Our results show PCOS patients have slightly but significantly higher positivity of aTPO antibodies but the prevalence of AIT was insignificant.

Value of repeat stimulated thyroglobulin testing in patients with differentiated thyroid carcinoma considered to be free of disease in the first year after ablation

BACKGROUND

In patients with differentiated thyroid carcinoma considered to be free of the disease after initial therapy, the appropriate timing or necessity of subsequent stimulated thyroglobulin (Tg) testing is uncertain. The objective of this study was to determine the value of a repeat stimulated Tg in patients considered to be free of disease 6-12 months after thyroid ablation, and also who continued to have serum Tg <1 ng/mL while on thyrotropin suppressive doses of thyroxine (T4) (Tg/T4), negative anti-Tg antibodies (TgAb), and a normal clinical examination 5 years after their initial therapy.

METHODS

The study participants were 203 patients who had total thyroidectomy followed by ablation with (131)I, who were considered to be free of disease 6-12 months after ablation (stimulated Tg <2 ng/mL in the absence of TgAb and negative diagnostic whole-body scanning), who had no recurrence, and who continued to have serum Tg/T4 of <1 ng/mL, negative TgAb and a normal clinical examination 5 years after initial therapy. These patients were evaluated with repeat stimulated Tg testing after 4 weeks of T4 withdrawal.

RESULTS

Repeat stimulated Tg values after 5 years were <2 ng/mL in 192 (94.6%) patients of whom 188 were <1 ng/mL. Subsequent follow-up after a mean of 102 months did not detect new cases of tumor recurrence in this subgroup. Eleven patients (5.4%) had stimulated Tg levels of >2 ng/mL. Neck ultrasonography (US) revealed metastases in three and other imaging methods detected metastases in five patients with negative US. In the other three patients, no metastases were detected initially or during follow-up. Gender, age, and tumor stage were not predictors of recurrence or elevated Tg upon repeat testing after 5 years.

CONCLUSIONS

The present results favor repeating stimulated Tg 5 years after ablation in patients who were initially considered to be free of disease and who continued to have Tg/T4 values of <1 ng/mL and negative TgAb tests. A negative predictive value of 100% was obtained for patients who continued to have low stimulated Tg values.

Experience with lentivirus-mediated CD40 gene silencing in a mouse model of Graves' disease

CD40 plays an important role in the pathogenesis of Graves' disease (GD). Inhibition of CD40 expression may be a promising treatment for GD. In this study, we used an animal model to investigate whether lentivirus expressing siRNA for CD40 (LV-CD40-siRNA) could be useful for the therapy of GD. BALB/c mice were injected with PBS alone (PBS group), negative lentivirus (control siRNA group), or LV-CD40-siRNA (CD40 siRNA group), 3 days before being treated with adenovirus expressing human TSHR A subunit (Ad-TSHR289) three times at 3-week intervals to induce GD model. Sera thyroxine (T(4)) levels were assayed by RIA. The expression of CD40 was detected at the mRNA level by real-time PCR and protein level by flow cytometry. The expression of CD40, CD80, and CD86 was significantly decreased in the CD40 siRNA group (P<0.05), while FOXP3 expression was increased compared to the control siRNA group (P=0.05). Mean T(4) levels were decreased 14% in the CD40 siRNA group compared to the control siRNA group. The rate of disease induction was similar among the three groups injected with Ad-TSHR289. LV-CD40-siRNA is a useful tool to inhibit the expression of CD40 in vivo, but it cannot decrease the incidence of hyperthyroidism in a limited period of time.

Investigations of thyroid hormones and antibodies in obesity: leptin levels are associated with thyroid autoimmunity independent of bioanthropometric, hormonal, and weight-related determinants

OBJECTIVES

Obesity can alter the thyroid hormone status as a result of a dysregulated endocrine loop between the hypothalamo-pituitary unit and adipose tissue. The adipocytokine leptin has been shown to promote autoimmunity; hence, we aimed to clarify whether leptin excess of obesity could increase the susceptibility to develop autoimmune thyroid disease (AITD).

STUDY DESIGN

This cross-sectional study was performed in a tertiary care center.

METHODS

Free thyroid hormones, TSH, thyroglobulin, and antithyroid antibodies levels were tested in 165 obese and 118 lean subjects. Results were plotted against variables related to body composition, leptin levels, glucose homeostasis, energy expenditure, and pattern of weight accrual.

RESULTS

Compared with controls, obese patients had lower free T3 levels and free T4 levels (P<0.01), greater prevalence of hypothyroidism (P<0.05), and higher commonness of antithyroid antibodies (P<0.05). As a marker of AITD, thyroid peroxidase antibodies were more frequent in the obese group (P<0.01). Correlation analysis showed that leptin levels were associated with AITD (P<0.01) independent of bioanthropometric variables. Multiple logistic regression analysis in pooled groups identified female sex and leptin as significant predictors of AITD.

CONCLUSIONS

Obesity increases the susceptibility to harbor AITD with an emerging role for leptin as a peripheral determinant, which needs to be confirmed in future investigations.

Perchlorate and thiocyanate exposure and thyroid function in first-trimester pregnant women

CONTEXT

Thyroid hormone, requiring adequate maternal iodine intake, is critical for fetal neurodevelopment. Perchlorate decreases thyroidal iodine uptake by competitively inhibiting the sodium/iodide symporter. It is unclear whether environmental perchlorate exposure adversely affects thyroid function in pregnant women. Thiocyanate, derived from foods and cigarette smoke, is a less potent competitive sodium/iodide symporter inhibitor than perchlorate.

OBJECTIVE

Our objective was to determine whether environmental perchlorate and/or thiocyanate exposure is associated with alterations in thyroid function in pregnancy.

DESIGN AND SETTING

We conducted a cross-sectional study at health centers in Cardiff, Wales, and Turin, Italy.

PATIENTS

During 2002-2006, 22,000 women at less than 16 wk gestation were enrolled in the Controlled Antenatal Thyroid Screening Study. Subsets of 261 hypothyroid/hypothyroxinemic and 526 euthyroid women from Turin and 374 hypothyroid/hypothyroxinemic and 480 euthyroid women from Cardiff were selected based on availability of stored urine samples and thyroid function data.

MAIN OUTCOME MEASURES

Urinary iodine, thiocyanate, and perchlorate and serum TSH, free T(4) (FT(4)), and thyroperoxidase antibody were measured.

RESULTS

Urinary iodine was low: median 98 microg/liter in Cardiff and 52 microg/liter in Turin. Urine perchlorate was detectable in all women. The median (range) urinary perchlorate concentration was 5 microg/liter (0.04-168 microg/liter) in Turin and 2 microg/liter (0.02-368 microg/liter) in Cardiff. There were no associations between urine perchlorate concentrations and serum TSH or FT(4) in the individual euthyroid or hypothyroid/hypothyroxinemic cohorts. In multivariable linear analyses, log perchlorate was not a predictor of serum FT(4) or TSH.

CONCLUSIONS

Low-level perchlorate exposure is ubiquitous but did not affect thyroid function in this cohort of iodine-deficient pregnant women.

Abnormal gamma globulin binding of thyroid hormones

Thyroid hormone levels were studied in a thyrotoxic patient, who was treated with propylthiouracil. He had heavily increased triiodothyronine concentrations, measured by radioimmunoassay, in spite of only mild clinical symptoms of thyrotoxicosis. A moderately increased serum triiodothyronine concentration was observed in another patient, who was euthyroid and who had recently recovered from subacute thyroiditis. By gel electrophoresis and precipitation tests with human anti-IgG and anti-IgA, a binding to the gamma globulins of both triiodothyronine and thyroxine was detected in patient 1, and of triiodothyronine in patient 2. Such abnormal binding may result in serious errors in the determination of thyroid hormone concentration by radioimmunoassay.

CD4+CD25+ naturally occurring regulatory T cells and not lymphopenia play a role in the pathogenesis of iodide-induced autoimmune thyroiditis in NOD-H2h4 mice

NOD-H2(h4) mice, which express I-A(k) on the NOD background, spontaneously develop autoimmune thyroiditis, a model of Hashimoto thyroiditis in humans, by adding iodide in the drinking water. Parental NOD mice have previously been shown to have intrinsic numerical abnormalities in peripheral lymphocytes and lymphocyte subpopulations such as CD4(+)CD25(+) naturally occurring regulatory T cells (Treg). Therefore we first investigated whether the similar abnormalities exist in NOD-H2(h4) mice. We observed that, compared with other non-autoimmune disease prone BALB/c and C57BL/6 mice, NOD-H2(h4) mice have lower numbers of splenocytes, CD3(+)T, CD4(+)T and CD8(+)T cells but the ratios of Treg to CD4(+)T cells were comparable. Increasing the numbers of peripheral lymphocytes by Complete Freund's Adjuvant immunization or splenocyte transfer did not affect development of thyroiditis, indicating that lymphopenia does not play a critical role in the pathogenesis of thyroiditis. We next examined the significance of Treg by depleting this lymphocyte subset with anti-CD25 antibody. Treg depletion, performed 4days before the administration of NaI water for 8 weeks, significantly exacerbated thyroiditis (p<0.01). Anti-thyroglobulin antibody titers also increased by Treg depletion (p<0.01) without changing the IgG2b to IgG1 ratios. In addition, expression levels of mRNA for IFN-gamma and IL-4 were enhanced in parallel. However, T(4) levels were similar between antibody-treated and untreated groups. Additional anti-CD25 administration at 3 weekly intervals did not influence these results. These data, together with previous studies on other mouse models of inducible thyroiditis and Graves' disease, indicate the role played by Treg in keeping anti-thyroid autoimmune reaction in check in experimental autoimmune thyroid diseases.

The prevalence of autoantibodies to: myosin, troponin, tropomyosin and myoglobin in patients with circulating triiodothyronine and thyroxine autoantibodies (THAA)

OBJECTIVE

Anti-thyroglobulin, anti-thyroid-peroxidase and anti-TSH receptor antibodies have been observed with high frequency in autoimmune thyroid diseases. Thyroid hormone auto-antibodies (THAA): anti-thyroxine (T4) and anti-triiodothyronine (T3), conversely, have been reported rarely. In both hyperthyroidism and hypothyroidism, patients suffer from muscle weakness and function disorders. The aim of our study was the evaluation of the occurrence rate of autoantibodies targeting muscle proteins in a group of 24 patients with circulating anti-T3 and/or anti-T4 autoantibodies. The control group consisted of 41 healthy blood donors.

METHODS

In polyethylene tubes coated with muscle antigens: actin, myosin, myoglobin, troponin and tropomyosin solid-phase radioimmunoassay was performed to detect autoantibodies. A reaction with 125I-labelled staphylococcus protein A was used for the detection of antibodies bound to the antigens on the tubes.

RESULTS

We found a high occurrence of antibodies to muscle proteins in patients with THAA. Anti-myoglobin autoantibodies were most frequent (54.2% of subjects), the binding index values was very high and exceeded normal values two to four fold. Anti-myosin autoantibodies were detected in 50% of subjects; anti-troponin autoantibodies in 33.3%, and anti-tropomyosin autoantibody in 3 patients (12.5%). Differences between the patients and the controls were statistically significant. The antibody binding index to actin was low and statistically insignificant.

CONCLUSIONS

Our study indicates that muscle protein antibodies, especially to myoglobin, myosin and troponin, are very frequently present in patients with autoimmune thyroid disease and circulating anti-T3 and anti-T4 autoantibodies, as well as in most cases of chronic thyroiditis with clinical symptoms of hypothyroidisms.

Hormonal change and cytokine mRNA expression in peripheral blood mononuclear cells during the development of canine autoimmune thyroiditis

To elucidate the hormonal change and alteration in cytokine expression in peripheral blood mononuclear cells (PBMC) during the early stage of autoimmune thyroiditis, we have developed a canine model of this disease, in which normal dogs were immunized with bovine thyroglobulin (Tg) and/or canine thyroid extract. Serum samples were collected weekly, anti-canine Tg antibody was measured by enzyme-linked immunosorbent assay (ELISA) and thyroid stimulating hormone (TSH) and total T4 levels by radioimmunoassay. We also assayed T lymphocyte proliferation in response to Tg, as well as measuring cytokine mRNA by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). All six dogs immunized with bovine Tg had both canine Tg autoantibody and anti-T4 antibody. When the sample from the highest TgAA titre time-point was compared with baseline the expression of mRNA encoding the Th1-type cytokine such as interferon (IFN)-gamma, interleukin (IL)-18 and IL-15 was increased during the development of autoimmune thyroiditis. Expression of the Th2-type cytokine, IL-6 showed minimal change and IL-4 expression was not detected in any of the samples. Expression of the T suppressive cytokine, IL-10 and transforming growth factor (TGF)-beta was increased in the presence of antigen stimulation. These findings suggest that, although autoimmune thyroiditis is an organ-specific autoimmune disease, systemic cytokine mRNA expression is also changed.

Early-onset thyrotoxicosis after unrelated cord blood transplantation for acute myelogenous leukemia

Thyroid dysfunction is a common complication after allogeneic hematopoietic stem cell transplantation (SCT). However, thyrotoxicosis as defined by elevated serum-free thyroxine (FT4) or free triiodothyronine (FT3) levels together with low thyroid-stimulating hormone (TSH) levels is rare after SCT. Here we describe 2 patients who developed thyrotoxicosis within the first 50 days after unrelated cord blood transplantation (CBT). Patient 1 is a 32-year-old woman with acute myelogenous leukemia (AML)-M5a who underwent CBT. On day +41, she developed tachycardia. On day +48, FT4 increased to 2.2 ng/dL and TSH was suppressed to less than 0.1 microU/mL. Antithyroid peroxidase antibody was positive. On day +83, FT4 spontaneously decreased to 1.4 ng/dL. Patient 2 is a 42-year-old man with AML-M4 who underwent CBT. On day +42, he developed tachycardia. On day +48, FT3 increased to 4.75 pg/mL and TSH was suppressed to 0.02 microU/mL. Antithyroid peroxidase antibody was positive. Eight months after CBT, his thyroid function spontaneously returned to normal. The presence of antithyroid peroxidase antibody suggested that immune-mediated reactions might be associated with the development of thyrotoxicosis after CBT in our patients. The present study shows that thyrotoxicosis can occur during very early periods after CBT.

The Colloidal Thyroxine (T4) Ring as a Novel Biomarker of Perchlorate Exposure in the African Clawed Frog Xenopus laevis

The purpose of this study was to determine if changes in colloidal thyroxine (T(4)) immunoreactivity can be used as a biomarker of perchlorate exposure in amphibian thyroid tissue. Larval African clawed frogs (Xenopus laevis) were exposed to 0, 1, 8, 93, and 1131 microg perchlorate/l for 38 and 69 days to cover the normal period of larval development and metamorphosis. The results of this study confirmed the presence of an immunoreactive colloidal T(4) ring in thyroid follicles of X. laevis and demonstrated that the intensity of this ring is reduced in a concentration-dependent manner by perchlorate exposure. The smallest effective concentration of perchlorate capable of significantly reducing colloidal T(4) ring intensity was 8 microg perchlorate/l. The intensity of the immunoreactive colloidal T(4) ring is a more sensitive biomarker of perchlorate exposure than changes in hind limb length, forelimb emergence, tail resorption, thyrocyte hypertrophy, or colloid depletion. We conclude that the colloidal T(4) ring can be used as a sensitive biomarker of perchlorate-induced thyroid disruption in amphibians.

Potentiation of humoral immune response and activation of NF-kappaB pathway in lymphocytes in experimentally induced hyperthyroid rats

This study explored the effect of hyperthyroid state on humoral immune response and NF-kappaB signaling in lymphocytes. Male Wistar rats were treated with l-thyroxin for four weeks. Animals were immunized with sheep red blood cells (SRBC) after three weeks of l-thyroxin treatment. After one week of immunization, serum anti-SRBC titer was measured and NF-kappaB signaling was studied in lymphocytes by Western blot analysis of p-IKB-alpha, IKB-alpha, and p65. These results were compared with that of control rats. Antibody response and density of p-IKB-alpha and p65 were significantly higher in l-thyroxin treated rats in comparison to controls. The antibody response was found to have significant correlation with density of p-IKB-alpha and p65. Our results indicate that NF-kappaB signaling pathway in lymphocytes is activated in hyperthyroid state which might play a role in potentiation of antibody response.

Screening for thyroid disease in pregnancy

Although gestational hyperthyroidism is uncommon (0.2%), hypothyroidism (autoimmune disease or suboptimal iodine intake) occurs in 2.5% of women and is predictive of reduced neonatal and child neuropsychological development and maternal obstetric complications. Postpartum thyroid dysfunction (PPTD) occurs in 5-9% of women and is associated with antithyroid peroxidase antibodies (antiTPOAb) in 10% of women in early pregnancy. Therefore, screening for thyroid dysfunction in pregnancy should be considered. T4 and thyroid stimulating hormone measurements could be used to screen for hypothyroidism, which would require levothyroxine intervention treatment. T4 supply is crucial to fetal nervous system maturation; currently, the recommended daily iodine intake is 200 microg, and this is not always achieved, even in the UK. At present, a randomised prospective trial is ongoing to provide the evidence base for this screening strategy. Meanwhile, it is reasonable to (a) optimise iodine nutrition during pregnancy; (b) ascertain women with known thyroid disease; (c) identify women at increased risk of thyroid disease-for example, those with other autoimmune diseases. PPTD can be predicted by measurement of antiTPOAb in early gestation.

Thyroxine-binding antibodies inhibit T cell recognition of a pathogenic thyroglobulin epitope

Thyroid hormone-binding (THB) Abs are frequently detected in autoimmune thyroid disorders but it is unknown whether they can exert immunoregulatory effects. We report that a THB mAb recognizing the 5' iodine atom of the outer phenolic ring of thyroxine (T4) can block T cell recognition of the pathogenic thyroglobulin (Tg) peptide (2549-2560) that contains T4 at aa position 2553 (T4(2553)). Following peptide binding to the MHC groove, the THB mAb inhibited activation of the A(k)-restricted, T4(2553)-specific, mouse T cell hybridoma clone 3.47, which does not recognize other T4-containing epitopes or noniodinated peptide analogues. Addition of the same THB mAb to T4(2553)-pulsed splenocytes largely inhibited specific activation of T4(2553)-primed lymph node cells and significantly reduced their capacity to adoptively transfer thyroiditis to naive CBA/J mice. These data demonstrate that some THB Abs can block recognition of iodine-containing Tg epitopes by autoaggressive T cells and support the view that such Abs may influence the development or maintenance of thyroid disease.

Quality specifications in thyroid diseases

BACKGROUND

Laboratory tests to support the diagnosis and management of thyroid diseases have undergone significant changes with the introduction of highly sensitive assays for thyroid stimulating hormone (TSH) and free T4 and T3 concentrations in plasma. Given the importance of these measurements, quality specifications are needed to ensure accurate results. Goals for precision and accuracy are available based on known intraindividual and interindividual biological variation.

METHODS

Results of external quality assurance (EQA) schemes are sufficient to document precision goals but survey materials are not commutable for use in determining bias or detect the presence of unusual antibodies on a case-by-case basis. Because TSH concentrations are inversely related to free T4, this physiologic relationship can be exploited for quality assurance purposes.

RESULTS

Significant discordance between this relationship can be caused by subclinical and potentially unrecognized disease, dysequilibrium caused by recent therapy, the presence of abnormal binding proteins or protein binding competitor drugs, and antibody interferences such as human antimouse antibody (HAMA) or rheumatoid factor.

CONCLUSION

A mechanism to automatically track discordances for subsequent follow and investigation can be an effective part of a quality assurance program for thyroid hormone measurements.

Studies on experimental iodine allergy: 1. Antigen recognition of guinea pig anti-iodine antibody

It has generally been thought that iodine allergy is cross-sensitive to various iodine-containing chemicals. However, this concept seems to deviate from the immunological principle that immune recognition is specific. To solve this contradiction, we hypothesize that iodine allergy is an immunological reaction to iodinated autologous proteins produced in vivo by iodination reaction from various iodine-containing chemicals. Antisera to iodine were obtained from guinea pigs immunized subcutaneously with iodine-potassium iodide solution emulsified in complete Freund's adjuvant (CFA). The specificity of guinea pig anti-iodine antiserum was determined by enzyme-linked immunosorbent assay (ELISA) inhibition experiments using microplates coated with iodinated guinea pig serum albumin (I-GSA). Antibody activities were inhibited by I-GSA, diiodo-L-tyrosine, and thyroxine, but not by potassium iodide, monoiodo-L-tyrosine, 3,5,3'-triiodothyronine, monoiodo-L-histidine, or diiodo-L-histidine, or by ionic or non-ionic iodinated contrast media. The results that antigen recognition of anti-iodine antibody is specific to iodinated protein support our hypothesis. While protein iodination usually takes place both at histidine residues as well as at tyrosine residues, only iodinated tyrosine acted as an antigenic determinant and no antibody activities to iodinated histidine were detected in our experimental iodine allergy model.

Chronic urticaria: association with thyroid autoimmunity

BACKGROUND

Though autoimmune phenomena have been regularly associated with chronic urticaria in adults, data in children are sparse.

AIM

To describe our experience with children and adolescents with chronic urticaria and autoimmunity.

METHODS AND RESULTS

Of 187 patients referred for evaluation of chronic urticaria during a 7.5 year period, eight (4.3%), all females aged 7-17 years, had increased levels of antithyroid antibody, either antithyroid peroxidase antibody (n = 4, >75 IU/ml), antithyroglobulin antibody (n = 2, >150 IU/ml), or both (n = 2). The duration of urticaria was four months to seven years. Five patients were euthyroid, one of whom was found to have increased antithyroid antibody levels five years after onset of the urticaria. One patient was diagnosed with Hashimoto thyroiditis three years before the urticaria, and was receiving treatment with thyroxine. Two other hypothyroid patients were diagnosed during the initial work up for urticaria (thyroxine 9.2 pmol/l, thyroid stimulating hormone (TSH) 40.2 mIU/l) and five years after onset of the urticaria (thyroxine 14 pmol/l, TSH 10.3 mIU/l). Both were treated with thyroxine but neither had remission of the urticaria. Five patients had a low positive titre of antinuclear antibodies.

CONCLUSION

Children with chronic urticaria should be screened periodically for thyroxine, TSH, and antithyroid antibodies, as thyroid autoimmunity and hypothyroidism may appear several years after onset of the urticaria.

[Clinical, hematological, biochemical and endocrinological aspects of 32 dogs with hypothyroidism]

During the years of 1996-2001, hypothyroidism was diagnosed at the clinic for small animal internal medicine, University of Zurich, in 32 dogs. Most of the dogs were large breeds. The most frequent clinical characteristics observed were exercise intolerance, obesity, dermatological, neurological and gastrointestinal signs. Predominant laboratory abnormalities were a low red blood cell count, increased concentration of cholesterol, triglycerides and fructosamin. 29 dogs had a T4 below the reference range (< 1.5 micrograms/dl), one dog had a T4 at the lower limit thereof (1.6 micrograms/dl). One dog had a T4 within the reference range (3.4 micrograms/dl), another had a very high T4 of 206.8 micrograms/dl; the results of the latter 2 dogs were interpreted as incorrectly increased T4 values due to in vitro interference with T4-autoantibodies. Diagnosis was confirmed in all of the dogs based on TSH-stimulation testing. Endogenous TSH (cTSH) measured parallelly, was elevated in only 60% of the dogs. In about 67% of the dogs, hypothyroidism was associated with thyroglobulin-autoantibodies. Canine hypothyroidism is a rather rare endocrine disorder in Switzerland. The TSH-stimulation test remains the gold standard in confirming the disease; a definitive diagnosis can be challenging for practitioners because bovine TSH, used for the TSH-stimulation test is not licensed for use in dogs. Since assessment of cTSH using current assays shows normal values in a high percentage of hypothyroid dogs, the diagnostic value is only limited. In most of the hypothyroid dogs T4 is decreased, with the presence of autoantibodies to T4, it can be normal or increased.

A major role for non-major histocompatibility complex genes but not for microorganisms in a novel murine model of Graves' hyperthyroidism

The etiology of Graves' disease is multifactorial. We investigated the role of genetic and environmental factors on the susceptibility to Graves' hyperthyroidism using a new murine model. Intramuscular injection of recombinant adenovirus expressing the thyrotropin receptor (AdCMVTSHR) induces Graves'-like hyperthyroidism (thyrotropin receptor [TSHR] antibodies, elevated thyroxine, and diffuse goiter) in more than 50% of female BALB/c mice. The relative contributions of major histocompatibility complex (MHC) and non-MHC genes on the susceptibility to hyperthyroidism were studied by immunizing BALB/c (H-2d), BALB.K (H-2k), and DBA/2J (H-2d) mice with AdCMVTSHR. Hyperthyroidism developed in approximately 50% of BALB/c and BALB.K mice but only 5% of DBA/2J mice, indicating a major role for non-MHC genes in disease development. The effect of environmental microorganisms was evaluated by comparing disease incidence in BALB/c mice maintained in pathogen-free conditions versus those in nonsterile, conventional housing, as well as by coadministering microorganism components (Escherichia coli lipopolysaccharide or yeast zymosan A) as adjuvants with AdCMVTSHR. Neither type of exposure to environmental pathogens influenced disease induction. In conclusion, non-MHC genes, but not infectious organisms, play a major role in the etiology of this novel murine model of Graves' disease.

Determination of autoantibodies to thyroglobulin, thyroxine and triiodothyronine in canine serum

Enzyme immunoassays (EIAs) for the determination of autoanti-bodies (AA) to thyroid antigens in canine serum were developed. Streptavidin (SA) was immobilized as capture molecule on microtitreplates (MTP). Thyroglobulin (Tg) purified from canine thyroids and the thyroid hormones thyroxine and triiodothyronine (T3 and T4) were conjugated to biotin labelling reagents and attached to the MTP over the SA-biotin bridge. Bound AA were detected with anti-dog-immunoglobulin G (IgG) labelled with horseradish peroxidase. Serum samples from dogs which were allotted to four groups were analysed: A (n = 31), biochemical evidence of hypothyroidism; B (n = 76), clinical signs of hypothyroidism; C (n = 47), euthyroid with non-thyroidal disease; D (n = 186), clinically healthy. The validity of the assays was tested with two different methods. After thiophilic absorption chromatography of positive sera, a positive reaction in the EIA was only detected in those fractions which coeluted with the canine IgG standard. Furthermore, the positive reaction was blocked by the addition of the corresponding antigen. In 55% of the hypothyroid dogs AA to Tg and/or T3 and T4, respectively, were found (up to a titre of 1 : 1600). In group B 34% of the dogs were diagnosed positive, but the titre was lower (up to 1 : 400). In the groups C and D the number of dogs with AA and their titre was significantly lower. Two different methods for distinguishing positive and negative test results were compared in order to increase the specificity of the tests without decreasing the sensitivity. The EIAs are precise and based on high agreement with previous reported assays able to discriminate dogs with thyroiditis from healthy ones. These assays represent a good alternative to the isotope assays generally used for the analysis of AA to T4 and T3.

Sensitive time-resolved fluoroimmunoassay for simultaneous detection of serum thyroid-stimulating hormone and total thyroxin with Eu and Sm as labels

Based on a novel cocoating strategy and dissociation enhancement lanthanide fluorescence immunoassay technique, a sensitive time-resolved fluoroimmunoassay (TRFIA) has been developed for simultaneous quantification of human serum thyroid-stimulating hormone (TSH) and thyroxin (T4) in a one-and-the-same assay procedure. The new cocoating strategy for preparing highly active surface anti-TSH and anti-T4 monoclonal antibodies (McAbs) was performed by a three-step protocol. Namely, anti-TSH McAb at high concentration (10 micro g/ml) and extensively biotinylated bovine serum albumin (BSA) at low concentration (0.5 micro g/ml) were coated on microwells by passive adsorption, then streptavidin was captured by the surface BSA-biotin, and finally biotinylated anti-T4 McAb was immobilized by the remnant binding sites of the bound streptavidin. In the present TSH/T4 TRFIA, both sandwich- and competitive-type configurations were involved, and Eu(3+) and Sm(3+) were used as labels for TSH and T4 detection, respectively. The method showed rapid kinetics; the equilibrium was reached within 30min at 37 degrees C due to the use of high concentrations of reaction reagents, rapid agitation, and small reaction volume. The lower limits of detection of the method were 0.028 mIU/L for TSH and 4.1 nmol/L for T4 with 20 micro L of sample volume. The assay ranges for TSH and T4 were 0.21-80.00 mIU/L and 20-300 nmol/L, respectively. The correlation between the TSH/T4 values obtained by the present TSH/T4 TRFIA and those obtained by commercial chemiluminescence immunoassay was satisfactory.

[Lanthanide fluorescent immune analysis for determination of hormone thyroxine in dry blood spots]

The determination of thyroxin (T4) is a basic confirmative test for congenital hypothyroidism. 70% cases of this period inborn disease are taking asymptomatic course. We developed immunofluorescent T4-assay in dried blood spots with anti-T4 monoclonal antibody and europium chelate (dianhydride of diethylentriaminipentaacetic acid (DA-DTPA)). This method requires DELFIA Plate Fluorometer 1232 (Wallac, Finland) or its sub modifications. Panel of monoclonal antibodies for T4 has been obtained. Type/subtype (IgG2b, IgG1), affinity constants (10(7)-10(8) M-1), cross reactivity to homologous structures (0-2%) were determined. Stable clones with high affinity and viability were selected for the development of the assay. Conjugates of thyroxin and europium chelate were synthesized. Inclusion of sodium salicylate (2 mg/ml) and EDTA (2 mM) into the buffer reduced the nonspecific signal. Limit for T4 detection (T4 standarts) was 10 nM with not more than 15% variation coefficient. Accuracy was estimated by Bio-Rad Lipochek Immunoassay Plus Control Kit. Obtained results were within control confidence interval.

[A case of hypothyroidism due to hashimoto disease that presented elevations of free T3 and free T4 by thyroid hormone autoantibodies]

When we commonly evaluate the thyroid function, we measure TSH, free T3 and free T4. However, there are some cases that are difficult to diagnose because of the existence of thyroid hormone autoantibodies. We experienced a case of a 14-year-old girl with diffuse struma whose TSH, free T3 and free T4 were elevated by detected with Amerlex M free T3 and free T4 kits, although she did not have any symptoms. As the free T4 level was low by the equilibrium dialysis method, we diagnosed this case as hypothyroidism due to chronic thyroiditis. Because we found thyroid hormone antibodies in her serum, we thought that this case presented pseudoelevations of free T3 and free T4 by the analogue method.

Early variations of host thyroxine and interleukin-7 favor Schistosoma mansoni development

Schistosoma mansoni induces, in the vertebrate host, cutaneous production of interleukin-7 (IL-7), which is beneficial for parasite establishment and development. Infection of mice deficient in IL-7 expression leads to parasite dwarfism. Because similar findings were previously described in hypothyroid mice, this study aimed to elucidate the potential link between IL-7 and thyroid hormones (THs), using several models including hypo- and hyperthyroid mice, modified either transiently or constitutively. Mice treated with thyroxine led to increased worm numbers and development of giant worms, whereas an iodine-deficient diet reduced parasite maturation, egg laying, and liver pathology. Conversely, mice genetically deficient for either of the nuclear TH receptors displayed normal worm development despite modifications in hormone levels, suggesting that thyroxine action is mediated through host receptors. In addition, no modification of antibody titers has been evidenced in thyroxine-treated mice, whereas antibody levels were altered in transgenic animals. These observations suggest that the immune system is not likely to be involved in the modifications of parasite development reported in this study. Interestingly, concomitant treatment with IL-7 and thyroxine had a synergistic effect, leading to recovery of very large worms, thus raising questions about the complexity of interactions between IL-7 and metabolic hormones.

Evaluation of an in-house enzyme-linked immunosorbent assay for quantitative measurement of serum total thyroxine concentration in dogs and cats

OBJECTIVE

To compare serum total thyroxine (T4) concentrations obtained with an in-house ELISA and a validated radioimmunoassay (RIA).

DESIGN

Laboratory trial.

SAMPLE POPULATION

50 canine and 50 feline serum samples submitted for measurement of total T4 concentration with the RIA; samples were selected to represent a wide range of concentrations (< 6 to 167 nmol/L).

PROCEDURE

Results of the ELISA and RIA were compared by calculating correlation coefficients, examining linearity, determining bias and precision, and evaluating clinical interpretations.

RESULTS

Correlation coefficients for results of the 2 methods were 0.84 for the canine samples and 0.59 for the feline samples. Examination of bias plots revealed large variations in ELISA results, compared with RIA results. For the feline samples, the ELISA consistently overestimated total T4 concentration obtained with the RIA. When results of the 2 methods were categorized (low, borderline low, normal, borderline high, or high), results were discordant for 24 (48%) and 29 (58%) of the canine samples and for 18 (36%) and 28 (56%) of the feline samples (depending on whether borderline high ELISA results were considered normal or high). Reliance on results of the ELISA would have led to inappropriate clinical decisions for 31 (62%) canine samples and 25 (50%) feline samples. The ELISA coefficients of variation for the pooled canine and feline samples were 18 and 28%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Substantial discrepancies between ELISA and RIA results for T4 concentrations were detected. Thus, we concluded that the in-house ELISA kit was not accurate for determining serum total T4 concentrations in dogs and cats.

Improved antibody coating protocol using a second antibody antiserum. Application to total thyroxin immunoassay

A complete antibody coating protocol for the preparation of dry antibody coated tubes is presented. This protocol is based on a recently described antibody immobilization principle. We modify this immobilization principle in order to improve and simplify the coating procedure. In addition, we propose a drying procedure that provides long-term storage stability of the antibody coated tubes. According to the modified protocol, polystyrene plastic tubes are first coated with rabbit gamma-globulins. The tubes are incubated with a sheep anti-rabbitIgG antiserum dilution. After incubation, antigen-specific antibody antiserum raised in rabbits is added directly into the tubes containing the sheep anti-rabbit IgG antiserum solution (difference from the original protocol). Finally, the tubes are washed, blocked, and dried following the drying procedure developed. The suitability of the modified protocol for the development of immunoassays requiring high loading of antibody was exemplified through the development of a RIA for total thyroxin. The estimated assay characteristics (detection limit 4 microg/L, dynamic range up to 210 microg/L, within-run CV 2.7-5.7%, between-run CV 5.1-7.3%, recovery 84.4-112%, cross-reactivity for T3 1.9%) were comparable with those provided by commercially available RIA kits for the determination of thyroxin.

Hypothalamus-hypophysis-thyroid axis, triiodothyronine and antithyroid antibodies in patients with primary and secondary Sjögren's syndrome

It has been well established that, anti-thyroglobulin antibodies (ATG) and anti-microsomal antibodies (AMC) may be present in various thyroid disorders and other systemic autoimmune diseases, including Sjögren's syndrome (SS). However, presence of circulating autoantibodies to thyroid hormones, i.e. both to triiodothyronine (T3) and tetraiodothyronine (T4), has not been studied extensively in SS. Autoantibodies to T3 and T4 are very important, because serum T3 and T4 levels may be detected spuriously higher or lower, due to the presence of these autoantibodies. Their presence should be suspected when measured serum thyroid hormone levels are not consistent with clinical status of the patient. SS is a slowly progressive, inflammatory autoimmune disease, affecting primarily the exocrine glands. Thyroid gland, being a target in some autoimmune diseases, is well known to be affected in SS as well. Keeping this possibility in mind, we investigated T3 autoantibody levels and thyroid gland involvement in patients with SS. Twenty-six SS patients (F/M:22/4) with a mean age of 46.6 years, were recruited in this study. Twelve of them were accepted as primary SS (pSS), while others had secondary SS (sSS) (7 with rheumatoid arthritis (RA), 3 with systemic lupus erythematosus (SLE), 3 with progressive systemic sclerosis (PSS) and 1 with sarcoidosis). Thyroid function tests, including T3, T4, fT3, fT4, TSH, ATG, AMC, T3 antibody measurements, thyroid scintigraphy, thyroid ultrasonography and TRH stimulation tests were performed in all patients. We compared our results with those of the twenty healthy normal controls. Serum ATG and/or AMC were detected in three patients with pSS (25%) and no patients with sSS. No significant difference could be shown in the other parameters, including T3 autoantibodies and thyroid function tests. TRH stimulation test was also normal, showing that the hypothalamus-hypophysis-thyroid axis was not affected in patients both with pSS and sSS. In conclusion, we found that T3 autoantibody levels in pSS, were not significantly higher than sSS and normal controls.

A Selenium-Containing Catalytic Antibody with Type I Deiodinase Activity

Acting as a mimic of type I deiodinase (DI), a selenium-containing catalytic antibody (Se-4C5) prepared by converting the serine residues of monoclonal antibody 4C5 raised against thyroxine (T4) into selenocysteines, can catalyze the deiodination of T(4) to 3,5,3'-triiodothyronine (T(3)) with dithiothreitol (DTT) as cosubstrate. Investigations into the deiodinative reaction by Se-4C5 revealed the relationship between the initial velocity and substrate concentration was subjected to Michaelis-Menten equation and the reaction mechanism was ping-pong one. The kinetic properties of the catalytic antibody were a little similar to those of DI, with Km values for T(4) and DTT of approximately 0.8 microM and 1.8 mM, respectively, and V(m) value of 270 pmol per mg protein per min. The activity could be sensitively inhibited by PTU with a Ki value of approximately 120 microM at 2.0 microM of T(4) concentration, revealing that PTU was a competitive inhibitor for DTT.

Morphological and functional development of the thyroid tissue in rainbow trout (Oncorhynchus mykiss) embryos

The development of the thyroid tissue in rainbow trout (Oncorhynchus mykiss) embryos between 20 and 88 days postfertilization (dpf) was studied using traditional histological methods in combination with immunostaining using antibodies raised against L-thyroxine (T4) and triiodo-L-thyronine (T3). In 20 dpf embryos, the thyroid primordium appeared as a simple tube aligned with the dorsal surface of the ventral aorta. The tubular primordium becomes progressively bifurcated at each end and follicles are formed by pinching off balls of cells from the tips of the bifurcations. The secretory activity of the thyroid tissue appears first as a synthesis phase, evident at 30 dpf, characterized by T4 and T3 immunostaining present only in the follicle lumen. A later hormone release or secretory phase was first evident for T4 immunostaining at 43 dpf and for T3 immunostaining at 46 dpf and was characterized by the presence of immunostaining both within the follicle lumen and also in the cytoplasm of some (but not all) thyrocytes. This stage was also coincident with a marked increase in the number of pituitary thyrotrophs. The proportion of embryos exhibiting immunostained thyrocytes increased progressively from 43 to 52 dpf, at which stage all embryos had T4- and T3-immunostained thyrocytes.

Site-specifically labeled photoprotein-thyroxine conjugates using aequorin mutants containing unique cysteine residues: applications for binding assays (Part II)

The jellyfish Aequorea victoria produces a protein, aequorin, which belongs to the class of Ca(2+)-dependent photoproteins known for their ability to emit visible light. This property of aequorin has allowed for its as a bioluminescent label in binding assays for a variety of analytes. Due to the excellent detection limits we demonstrated in assays for small peptides using a fusion protein between the peptide of interest and the photoprotein, our next goal was to expand the range of possible analytes for producing homogeneous populations of conjugates with the aequorin label to those that were nonpeptidic in nature. Recently, we prepared and characterized four aequorin mutants containing unique cysteine residues at various positions in the polypeptide chain. In the work reported here, the four aequorin mutants were each conjugated with a maleimide-activated methyl ester derivative of thyroxine, a hormone frequently determined to evaluate thyroid function. The thyroxine-aequorin mutant conjugates were characterized in terms of the bioluminescence activities and binding properties with an anti-thyroxine monoclonal antibody for possible future employment in either heterogeneous or homogeneous binding assays for thyroxine and/or other desired analytes.

Sequencing of anti-thyroxine monoclonal antibody fab fragment by ion trap mass spectrometry

A comprehensive mass spectrometric strategy is described for the sequencing of anti-thyroxine monoclonal antibody Fab region (48 000 Da). After reduction and S-carboxymethylation of the Fab, the modified light chain and Fd fragment were separated and subjected to multiple proteolytic digestions. The resulting digests were characterized by on-line microbore liquid chromatography/electrospray ionization ion trap mass spectrometry. Database search against published immunoglobulins (IgGs) allowed identification of all the peptides in constant domains. The homologous framework residues in the IgGs were utilized as 'sequence maps' for the sequence determination of variable domains. S-Carboxymethylation with an isotopic-enriched moiety greatly facilitated the recognition and data elucidation of cysteinyl peptides through the unique isotopic distribution patterns specific to the modified peptides. Methylation of peptide mixtures provided additional information for the interpretation of MS/MS spectra, allowing easy differentiation of Asp/Asn and Gln/Glu pairs. This study clearly demonstrates the power of mass spectrometry for the sequencing of antibodies without knowing the corresponding DNA sequences.

Time-resolved fluorescence immunoassay of thyroxine in serum: immobilized antigen approach

With T(4)-bovine IgG as a solid-phase antigen, we have developed a direct competitive-type immunoassay for serum total thyroxine (TT(4)), which depends on the competitive distribution of europium-labeled anti-T(4) monoclonal antibody between solid-phase-bound T(4) and the T(4) in the sample or standard. The captured fraction of the tracer was measured after a dissociation-enhancement step. Four different T(4) protein conjugates were synthesized, of which T(4)-bovine IgG was selected as the most favorable for the preparation of solid-phase antigen. The sensitivity was 3.5 ng/ml with a sample volume of 20 microl. T(4) values obtained by this procedure agreed well with those obtained by RIA (r = 0.967, n = 38) and EG&G Wallac TRFIA (r = 0.926, n = 64). All other quality criteria was also fulfilled with respect to precision, accuracy, and dynamic range.

Antigenic and immunogenic properties of totally synthetic peptide-based anti-fertility vaccines

In this study we describe the results of experiments in which a variety of totally synthetic luteinizing hormone releasing hormone (LHRH) vaccines were assembled and examined for their abilities to elicit antibody responses and induce sterility in mice. It is shown that totally synthetic vaccines consisting of a 15 residue-defined T cell epitope and the 10 residue LHRH epitope not only induced high titers of antibody but also induced sterility. This effect did not appear to correlate with antibody titer, antibody isotype or comparative antibody affinity, but may be related to the length of time for which antibodies are present to exert their influence.

Identification of thyroid hormone residues on serum thyroglobulin: a clue to the source of circulating thyroglobulin in thyroid diseases

Thyroglobulin (Tg) present in the serum of normal individuals and patients with thyroid disorders could be partly newly synthesized non-iodinated Tg and partly Tg containing iodine and hormone residues originating from the lumen of thyroid follicles. With the aim of examining the contribution of the latter source of Tg to the elevation of serum Tg concentration in thyroid pathophysiological situations, we devised a procedure to identify thyroxine (T4) and tri-iodothyronine (T3) residues on Tg from unfractionated serum. A two-step method, basedon (i)adsorption of Tg on an immobilized anti-human Tg (hTg) monoclonal antibody (mAb) and (ii)recognition of hormone residues on adsorbed Tg by binding of radioiodinated anti-T4 mAb and anti-T3 mAb, was used to analyze serum Tg from patients with either Graves' disease (GD), subacute thyroiditis (ST) or metastatic differentiated thyroid cancer (DTC). Purified hTg preparations with different iodine and hormone contents were used as reference. Adsorption of purified Tg and serum Tg on immobilized anti-hTg mAb ranged between 85 and 90% over a wide concentration range. Labeled anti-T4 and anti-T3 mAbs bound to adsorbed purified Tg in amounts related to its iodine content. Tg adsorbed from six out of six sera from ST exhibited anti-T4 and anti-T3 mAb binding activities. In contrast, significant mAb binding was only observed in one out of eight sera from untreated GD patients and in 1 out of 13 sera from patients with DTC. The patient with DTC, whose serum Tg contained T4 and T3, represented a case of hyperthyroidism caused by a metastatic follicular carcinoma. In conclusion, we have identified, for the first time, T4 and T3 residues on circulating Tg. The presence of Tg with hormone residues in serum is occasional in GD and DTC but is a common and probably distinctive feature of ST.

Thyroid autoimmunity in children and adolescents with Type 1 diabetes mellitus

Type 1 diabetic children and adolescents often present with autoimmune thyroid disorders. Two hundred and four diabetic patients, less than 20 years old, were studied in order to diagnose these diseases. The prevalence of thyroid autoimmune disorders was 17.6% and, of those, chronic autoimmune thyroiditis was the most frequent. Microsomal autoantibodies correlated more accurately with the presence of chronic autoimmune thyroiditis than thyroglobulin autoantibodies. The thyroid status of most of the patients with positive markers was euthyroidism (77%), but subclinical hypothyroidism (11%), overt hypothyroidism (3%), subclinical hyperthyroidism (3%) and overt hyperthyroidism (6%) were also present. Autoimmune thyroid disorders were the most prevalent immunological processes affecting diabetic patients. No significant associations of thyroid autoimmunity and other autoimmunological disorders, such as celiac disease or presence of other autoimmune antibodies, were found.

Iodination of human thyroglobulin (Tg) alters its immunoreactivity. II. Fine specificity of a monoclonal antibody that recognizes iodinated Tg

In a previous investigation, we found that murine MoAb 42C3, raised against human Tg, recognized Tg differently depending upon its level of iodination of Tg. A possible explanation for this finding is that iodine is directly involved with the specific epitope recognized by MoAb 42C3. In the present study, we report that the binding of MoAb 42C3 to iodinated Tg is inhibited by T4, T3, reverse T3 (rT3), triiodothyroacetic acid (triac), diiodothyronine (T2), diiodotyrosine (DIT), but not by thyronine (TO) or tyrosine. The order of inhibition of these iodinated compounds is T4 > T3 > rT3 > triac > T2 > DIT. The MoAb 42C3 does not have the same specificity as the T3, T4-receptor since the order of binding of these iodinated compounds on the receptor differed from the order of their inhibition of this MoAb. Monoclonal antibody 42C3 also recognized non-iodinated Tg that was subsequently iodinated in vitro. It failed to recognize another protein, bovine serum albumin, that was iodinated in vitro by the same method. These results suggest that iodinated tyrosines and thyronines determine the binding specificity of MoAb 42C3. The inhibitory effects of these compounds on MoAb 42C3 depend on their iodine content as well as location of iodine in the aromatic ring.

Thyroglobulin peptides of specific primary hormonogenic sites can generate cytotoxic T cells and serve as target autoantigens in experimental autoimmune thyroiditis

Previously we demonstrated that thyroxine (T4)-containing, 12-mer peptides from positions 5 (1-12) and 2553 (2549-2560), as well as thyronine (T0)-substituted 2553 peptide, derived from human (H) thyroglobulin (Tg) are capable of activating T cells that infiltrate the thyroid (thyroiditogenic). In contrast, peptides T4(2567) and T0(2567) (2559-2570) are not. To determine if these thyroiditogenic peptides, T4(5), T4(2553), and T0(2553), activated cytotoxic T cells (Tc) and served as target autoantigens when loaded onto indicator cells (BW5147 lymphoma, H2k), lymph node cells from CBA mice immunized with mouse (M) Tg were cultured in vitro with MTg, HTg, or Tg peptide. After MTg or HTg activation, Tc were detected for both MTg- and HTg-loaded target cells in an 18-h, 51Cr-release assay at an effector:target cell ratio of 50:1. These Tc also killed target cells labeled with T4(5), T4(2553), or T0(2553), but not the control peptide T4(2567). When MTg-primed lymphocytes were cultured with T4(5), T4(2553), or T0(2553), specific Tc were also generated against target cells labeled with the respective peptide. The data suggest that one of the thyroiditogenic properties of these peptides previously shown by adoptive transfer of thyroiditis is related to the generation of Tc. In addition, these conserved autoepitopes of Tg also serve as target antigens for Tc.