concanavalin-a and Hypothyroidism

The regulation of TSH bioactivity in humans is not completely understood.. The aim of the study was to investigate the role of serum thyroid hormones in regulating the bioactivity of TSH.. We determined in vitro TSH bioactivity and glycosylation in nine patients (six females and three males, age 41.3 yr) with primary hypothyroidism before and after L-T(4) replacement, in 11 age- and sex-comparable controls (seven females and four males, age 37.6 yr), and in two thyroidectomized patients with TSH-secreting adenomas during and after L-T(4) withdrawal.. In vitro TSH bioactivity was measured by a sensitive and specific bioassay based on cAMP generation by Chinese hamster ovary cells transfected with human TSH receptor. TSH glycosylation was assessed by concanavalin A lectin and ricin column affinity chromatography.. In vitro TSH bioactivity in hypothyroid patients was low as compared with controls (0.48 +/- 0.1 vs. 1.1 +/- 0.2; P = 0.004) and increased during L-T(4) (0.48 +/- 0.1 vs. 0.8 +/- 0.1; P = 0.01). A strong significant correlation (r = +0.80; P = 0.004, Spearman) was observed between the absolute increments of serum TSH bioactivity and T(3) during L-T(4) replacement. The degree of sialylation was elevated in hypothyroid patients before treatment (47 +/- 2.4% vs. 29 +/- 4.3%; P = 0.002) and decreased significantly after L-T(4) (47 +/- 2.4% vs. 33 +/- 4.3%; P = 0.02). The mannose content of serum TSH in hypothyroid patients was similar to controls and did not change during L-T(4). In vitro TSH bioactivity also decreased in patients with TSH-secreting adenomas during L-T(4) withdrawal.. These data indicate that serum thyroid hormone level is a positive regulator of TSH bioactivity.

Topics: Adenoma; Adult; Animals; CHO Cells; Chromatography, Affinity; Concanavalin A; Cricetinae; Cricetulus; Cyclic AMP; Female; Glycosylation; Hormone Replacement Therapy; Humans; Hypothyroidism; Immunoassay; Male; Mannose; Middle Aged; Neuraminidase; Receptors, Thyrotropin; Ricin; Thyroid Hormones; Thyroidectomy; Thyrotropin; Thyroxine; Transfection

Concanavalin A (Con A) activates T lymphocytes and causes acute T-cell-mediated hepatic injury in mice. Decreased thyroid hormonal production is associated with a variety of immunological manifestations, including inactivation of macrophages with reduced TNF production and reduced soluble IL-2 receptors in the serum. We have recently shown that hypothyroidism prevents the development of cirrhosis and also minimizes hepatic damage in rats with fulminant hepatic failure. In the present study we examined the effects of hypothyroidism on a mouse model of Con A induced T cell-mediated acute hepatitis.. Hypothyroidism was induced both medically (MMI, PTU) and surgically. Eight groups of 10 mice each were studied: euthyroid controls (2 groups: water, Con A) and hypothyroid (6 groups: MMI, PTU, Surgical, MMI-Con A, PTU-Con A, Surgical-Con A).. Hepatic inflammation was significantly decreased in each of the Con A treated hypothyroid groups of mice. The serum transaminases, TNF-alpha and IL-6 levels were significantly elevated in the Con A treated group while near normal levels were found in the hypothyroid Con A treated groups (mean+/-SE AST: 1499+/-18 vs 78+/-10 IU/l, p<0.001; TNF: 2500+/-250 vs 135+/-15 pg/ml, p<0.001, IL-6: 12,200+/-300 vs 1260+/-140 pg/ml, p<0.001, respectively).. Hypothyroidism, independent of the mode of induction, can effectively inhibit the development of acute T cell-mediated liver damage in mice. These results suggest that some decrease in thyroid function might have a role in the prevention of immune mediated liver diseases.

Topics: Alanine Transaminase; Animals; Aspartate Aminotransferases; Concanavalin A; Cytokines; Hypothyroidism; Immunity, Cellular; Inflammation; L-Lactate Dehydrogenase; Liver; Male; Methimazole; Mice; Mice, Inbred BALB C; Propylthiouracil; T-Lymphocytes; Thyroidectomy; Time Factors

This study analyzed the structural differences of the carbohydrate chains of circulating free alpha-submit (alpha-SU) hypersecreted in various non-tumoral (primary hypothyroids, postmenopausal women, patients with chronic uremia, normal fetuses) and tumoral (gut carcinoids, TSH-, GH- and pure alpha-secreting pituitary adenomas) clinical conditions. Carbohydrate structures of free alpha-SU were investigated by means of lectin affinity chromatography using Concanavalin A (Con-A), which allows the separation of free alpha-SU in three different fractions (unbound = UB, weakly bound = WB and firmly bound = FB) depending on the nature and maturation of glycosylated chains. The concentrations of alpha-SU in serum and in Con-A fractions were measured by a sensitive and specific IRMA. Free alpha-SU hypersecreted from postmenopausal women, primary hypothyroids, and patients with chronic uremia showed similar binding patterns to Con-A, the percentage of UB fractions (UB: 44.5 +/- 1.9%, 39.5 +/- 3.8%, 48.2 +/- 5.6% respectively) being higher than both WB and FB fractions (WB: 33.2 +/- 1.4%, 30.7 +/- 4.6%, 28.5 +/- 2.1%; FB: 22.3 +/- 0.7%, 29.8 +/- 6.6%, 23.3 +/- 4.2% respectively). In normal fetuses the amount of UB fraction was very high (UB: 70.7 +/- 5.4%). Free alpha-SU from patients with TSH- and GH-secreting adenomas showed a binding pattern to Con-A significantly different from that observed in postmenopausal women taken as controls, the WB fractions being significantly higher (WB: 56.9 +/- 16.8% and 71 +/- 12.4% respectively, P < 0.001). A typical pattern of elution on Con-A, characterized by a prevalence of immature alpha-SU molecules eluted in the FB fraction, was found in patients with pure alpha-secreting adenomas. This chromatographic behavior was significantly different from that seen in the controls, as well as in other pituitary tumors and in gut carcinoids (FB: 41.8 +/- 5.0%, 22.3 +/- 0.7%, 16.8 +/- 6.6%, 10.6 +/- 2.0% respectively). Moreover, in these latter patients the pattern of free alpha-SU binding was exactly the opposite of that observed in pure alpha-secreting adenomas, with a prevalence of mature alpha-SU molecules (UB: 59.1 +/- 4.4 vs 18.3 +/- 7.2%). In conclusion, our data on Con-A affinity chromatography clearly demonstrate that carbohydrate branching of circulating free alpha-SU varies in patients with pituitary adenomas as compared with patients with gut carcinoids or other non-tumoral conditions. Moreover, the finding of a greater prop

Topics: Adenoma; Adult; Carcinoid Tumor; Chromatography, Affinity; Concanavalin A; Fetus; Glycoconjugates; Glycoprotein Hormones, alpha Subunit; Humans; Hypothyroidism; Intestinal Neoplasms; Pituitary Neoplasms; Postmenopause; Protein Binding; Uremia

The inhibitory effect of an antithyroid drug on mouse T lymphocytes was investigated. Inbred C57BL/6 mice were provided with an antithyroid drug, methimazole, for 2, 4 and 6 weeks and the in vitro responses of the lymphocytes were studied. The proliferative responses of T lymphocytes from the spleen of methimazole (MMI)-treated mice significantly (p < 0.05) decreased following concanavalin A stimulation, and the inhibitory effect became prominent with the increased duration of MMI treatment. A concomitant increase in the frequency of induced sister-chromatid exchanges was also observed in these T lymphocytes. When the splenocytes were stimulated with concanavalin A for 24 h, their ability to produce interleukin-2 (IL-2) was significantly decreased (p < 0.05). The results indicated that methimazole interfered with the normal proliferation of T lymphocytes by suppressing the production of IL-2, a cytokine also known as T cell growth factor, as well as inducing a higher incidence of sister-chromatid exchange during cell division.

Topics: Animals; Cell Division; Concanavalin A; Hypothyroidism; Immunosuppressive Agents; Interleukin-2; Male; Methimazole; Mice; Mice, Inbred C57BL; Sister Chromatid Exchange; T-Lymphocytes

Circadian rhythm of TSH secretion is characterized by a pronounced nocturnal increment that is not followed by the expected rise of circulating thyroid hormone levels. These findings suggest that the nocturnal TSH surge may be constituted by molecules with reduced bioactivity. We, therefore, investigated TSH bioactivity (measured as cAMP accumulation in FRTL-5 cells) and its carbohydrate structure (by Concanavalin A affinity chromatography) in different blood pools taken during the day and night from seven normal subjects and from one patient with mild (mPH) and five with severe primary hypothyroidism (sPH). Patients with sPH were also studied during low dose L-T4 treatment. Cosinor analysis showed a significant TSH circadian rhythm in the control group and in L-T4-treated sPH patients. The nocturnal TSH surge was not followed by any increase in free thyroid hormone levels. In normal subjects, the daytime ratio of TSH bioactivity to immunoreactivity (TSH B/I) was higher than the nocturnal one [1.4 +/- 0.6 (+/- SD) vs. 1.1 +/- 0.6; P < 0.02]. The same pattern was observed in the only mPH patient (1.0 +/- 0.2 vs. 0.7 +/- 0.1; P < 0.01), but not in the sPH patients (0.8 +/- 0.3 vs. 0.7 +/- 0.1; P = 0.3). L-T4 administration to sPH patients caused the daytime TSH B/I to increase and restored the day/night difference in the TSH B/I (1.0 +/- 0.3 vs. 0.8 +/- 0.3; P < 0.02). Concanavalin A chromatography showed that a higher percentage of less mature forms of TSH are secreted during the night. These data indicate that TSH molecules secreted during the night are less bioactive and differently glycosylated than those circulating in the same individual during the day, thus explaining why thyroid hormone levels do not rise after the nocturnal TSH surge. In sPH patients, the TSH circadian rhythm is restored during L-T4 administration, and day/night differences in TSH B/I similar to those recorded in normal subjects are observed.

Topics: Adult; Aged; Biological Assay; Chromatography, Affinity; Circadian Rhythm; Concanavalin A; Female; Humans; Hypothyroidism; Male; Middle Aged; Reference Values; Thyroid Hormones; Thyrotropin; Thyroxine

Carbohydrate structures of intrapituitary and circulating TSH were studied by Concanavalin-A (Con A) and ricin lectin chromatography under different clinical conditions. Con A permits the separation of molecules differing in the extent of their carbohydrate branching, whereas ricin gives an estimation of the degree of their sialylation. Intrapituitary TSH was more retained on Con A and less sialylated than circulating hormone, suggesting that carbohydrate chains of intrapituitary molecules are less mature than those present in the circulation. A greater proportion of TSH firmly bound to Con A, compared to control values, was found in sera from fetuses and patients with uremia, TSH-secreting adenomas, and central hypothyroidism. In primary hypothyroid patients, TSH binding to Con A was similar to that found in controls, but a greater percentage of sialylated forms was seen. In central hypothyroidism patients, TSH released in response to TRH was less sialylated. Interestingly, no sialylated TSH was found in normal fetuses. In conclusion, the present data show that both TSH carbohydrate branching and sialylation may vary in different clinical conditions. As some of the above clinical conditions are known to be accompanied by variations in the bioactivity of circulating TSH, the finding of changes in TSH carbohydrate structures further supports the view that glycosylation modulates the expression of TSH biological activity.

Topics: Adenoma; Carbohydrates; Chromatography, Affinity; Concanavalin A; Female; Fetus; Humans; Hypothyroidism; Isoelectric Focusing; Male; Molecular Structure; Pituitary Gland; Pituitary Neoplasms; Pregnancy; Ricin; Thyrotropin; Uremia

Preincubation of rat hepatocytes with isoproterenol induces homologous beta-adrenergic desensitization evidenced both in whole cells (cyclic AMP accumulation) and membranes (adenylyl cyclase activity). This desensitization is associated with and quantitatively similar to a loss of beta 2-adrenoceptors from the plasma membrane. Desensitization did not alter the affinities of isoproterenol for the [125I]iodocyanopindolol binding sites nor reduce the ability of guanine nucleotides to modulate agonist affinity, i.e., the receptors that remain in the surface of plasma membrane after desensitization (approximately 50%) retain their functional integrity. When membranes from isoproterenol-desensitized hepatocytes were treated with alkaline phosphatase, no attenuation of the desensitization was observed. Cholera toxin-catalyzed ADP-ribosylation was not decreased but rather slightly increased in membranes from desensitized cells as compared to the controls. Our data indicate that in hepatocytes, a loss of beta 2-adrenoceptors from the plasma membrane is closely associated to the homologous desensitization induced by isoproterenol.

Topics: Adenosine Diphosphate Ribose; Adenylyl Cyclases; Alkaline Phosphatase; Animals; Autoradiography; Binding, Competitive; Cell Membrane; Cholera Toxin; Concanavalin A; Cyclic AMP; Female; Hypothyroidism; In Vitro Techniques; Iodocyanopindolol; Isoproterenol; Kinetics; Liver; Pindolol; Rats; Rats, Wistar; Receptors, Adrenergic, beta

TSH from human serum was separated into classes by serial lectin affinity chromatography using Concanavalin-A (ConA), lentil, and ricin lectins. TSH from 10 euthyroid subjects, 40 patients with primary hypothyroidism, and 1 patient with central hypothyroidism was studied. The patterns of ConA and lentil affinity binding were similar for diverse patients; forms of TSH that bound firmly to ConA also tended to bind firmly to lentil. Differences in TSH-ricin binding suggested that there were differences in the sialylation of TSH in sera of euthyroid, primary, and central hypothyroidism patients. For euthyroid subjects, 16.1 +/- 5.4% (mean +/- SD) of the TSH bound to ricin, while after neuraminidase treatment, 38.4 +/- 5.4% bound. For patients with primary hypothyroidism, 23.5 +/- 6.0% of the TSH bound to the ricin, while after neuraminidase treatment, 65.7 +/- 8.8% bound. The increase in ricin binding induced by neuraminidase treatment was significantly higher for TSH from patients with primary hypothyroidism than in that from euthyroid subjects (42.3 +/- 7.6% vs. 22.3 +/- 4.4%; P less than 0.01) and was greater for long term than for short term hypothyroid patients (49.5 +/- 5.0% vs. 36.5 +/- 6.5%; P less than 0.01). While 30% of native TSH from the serum of the patient with central hypothyroidism bound to ricin, the amount bound increased only 17.6% after neuraminidase treatment. McKenzie bioassay of pituitary-derived TSH that was similarly fractionated using ricin failed to show detectable differences in bioactivity among the lectin column fractions. Thus, 1) circulating human TSH can be consistently separated into discrete classes using serial lectin affinity chromatography; 2) there is relatively more core fucosylation of the less processed high mannose and hybrid forms of TSH and less core fucosylation of more processed complex forms; 3) ConA and lentil binding of TSH in primary and central hypothyroidism is similar to that in the euthyroid state; 4) patients with primary hypothyroidism have more sialylated TSH than a patient with central hypothyroidism or euthyroid subjects; and 5) the degree of TSH sialylation increases with prolonged primary hypothyroidism.

Topics: Adult; Aged; Aged, 80 and over; Binding Sites; Chromatography, Affinity; Concanavalin A; Fabaceae; Female; Glycopeptides; Humans; Hydrolysis; Hypothyroidism; Lectins; Male; Middle Aged; Molecular Structure; N-Acetylneuraminic Acid; Neuraminidase; Plant Lectins; Plants, Medicinal; Ricin; Sialic Acids; Thyrotropin

Euthyroid Cornell K strain and sex-linked dwarf (SLD) strain cockerels (which have abnormally low serum triiodothyronine concentrations) were supplemented with either 0, 0.01, 0.1, or 1.0 ppm of triiodothyronine (T3) in the diet. Peripheral blood lymphocytes (PBL) from these cockerels were obtained by slow-speed centrifugation (slow-spin-prepared PBL). The proliferative response of these PBL to phytohemagglutinin (PHA) and concanavalin A (Con A) was determined when the chicks were 6, 9, and 12 weeks of age. Con A responsiveness was also determined in 12-week-old cockerels using PBL which were separated on Ficoll (Ficoll-prepared PBL). Using slow-spin-prepared PBL, PHA, and Con A responsiveness increased in both strains with increasing levels of T3 supplementation. This enhancing effect of T3 was particularly evident in older cockerels. In 6- and 12-week-old SLD strain cockerels, the PHA:Con A response ratio was significantly (P less than 0.05) lower than in K strain cockerels. At 12 weeks of age the PHA:Con A response ratio of the SLD strain was elevated to K strain control levels by T3 supplementation. Therefore, the lower PHA:Con A response ratio in the SLD strain appears to be partially due to the existing peripheral hypothyroidism in this strain. Using Ficoll-prepared PBL, the effects of T3 on Con A responsiveness differed from those observed when slow-spin-prepared PBL were used. From this study we conclude that T3 supplementation affects mitogen responsiveness and the PHA:Con A response ratio. However, the effects of T3 on mitogen responsiveness depend on the age of the chicken, the level of T3 supplemented, the T cell population stimulated, and the method of lymphocyte enrichment.

Topics: Aging; Animals; Chickens; Concanavalin A; Dietary Proteins; Dose-Response Relationship, Immunologic; Hypothyroidism; Leukocyte Count; Lymphocyte Activation; Male; Monocytes; Phytohemagglutinins; T-Lymphocytes; Triiodothyronine

Five Persian Jews were detected with the polyglandular deficiency syndrome (PDS). Primary hypoparathyroidism and hypogonadism were present in each, adrenal insufficiency in two, and insulin-dependent diabetes mellitus and latent hypothyroidism in single subjects. The percentage of T and B cells, and the mononuclear cell response to phytohemagglutinin and Concanavalin A were normal in all five. IgG and IgA levels and the OKT4+/OKT8+ cell ratio were low in one subject. Antinuclear and antithyroid antibodies were present in one subject. HLA-DR5 was present in 4/4, HLA-24 and B5 (B51) in 3/4 subjects. A single case of isolated hypoparathyroidism (IHP) was detected among 12 first degree relatives. HLA antigens B8, DR3, were absent in all of these subjects. Seven non-Iranian Jews with IHP were also examined. HLA A26 or A25 were present in all seven. Persian Jews appear to have a unique variant of PDS.

Topics: Adolescent; Adrenal Insufficiency; Adult; Antibodies, Antinuclear; B-Lymphocytes; Concanavalin A; Diabetes Mellitus, Type 1; Female; HLA Antigens; Humans; Hypogonadism; Hypoparathyroidism; Hypothyroidism; Immunoglobulin A; Immunoglobulin G; Iran; Jews; Lymphocyte Activation; Male; Monocytes; Phytohemagglutinins; Syndrome; T-Lymphocytes

The response of lymphocytes to concanavalin A (Con A) was examined in the functionally hypothyroid SLD strain and the normal K strain chickens which were fed diets with or without T3 supplementation (0.1, 0.5 and 1.0 ppm) since the time of hatch. Peripheral blood lymphocytes (PBL) from 3 and 12 week old male and female chickens were incubated with Con A for 60 h. Mitogenic responsiveness was assessed by measuring the uptake of 3H-thymidine during the last 24 h of incubation. There was no difference in the mitogen response between male and female chickens. The mitogen responsiveness of PBL from the K strain tended to be greater than that from the SLD strain at both ages. The lowest dose of T3 (0.1 ppm) had no effect on the mitogen response of 3-week-old K strain chicks but caused an increase in mitogen response in 3-week-old SLD and in 12-week-old birds of both strains. Supplementation with 0.5 and 1.0 ppm T3 tended to decrease mitogen responsiveness in the K and SLD strain at both ages. The effect of treatment on thymus weights, bursa weights, and lymphocyte concentrations of the blood was also assessed.

Topics: Animals; Body Weight; Chickens; Concanavalin A; Female; Hypothyroidism; Leukocyte Count; Lymphocyte Activation; Lymphoid Tissue; Male; Organ Size; Poultry Diseases; Sex Factors; T-Lymphocytes; Triiodothyronine

We have studied the effect of thyroid disfunction during the postnatal period, on the serum and brain levels of rat alpha-fetoprotein (AFP) and albumin. Hypothyroidism was induced by treatment of pregnant rats and their newborn pups with 2-mercapto-1-methylimidazole(methimazole). Hyperthyroidism was provoked in newborns by daily injections of thyroxine (0.25 micrograms/g body wt) from the 3rd postnatal day weaning. Impaired growth, lower brain size, altered behaviour and morphological features observed were according to an altered thyroid status. Hypothyroid rats showed a significantly reduction in serum AFP concentration (78% of control values at 8 days of age) and a slight increase in that of albumin. level could be appreciated. Thyroxine supplementation (0.2 micrograms/rat/day) corrected most of these alterations. Hyperthyroidism induced a drastic fall in both serum and brain AFP levels (about 48% of the corresponding control values). Albumin concentration in serum was augmented significantly from the 12th postnatal day, but its brain levels did not change significantly. In hyperthyroid rats, a significant reduction (37% relative to controls) in the concanavalin A-non reactive microform of AFP, was observed. This alteration of the glycosylation pattern of AFP could be due to the inhibition by thyroxine of the activity of the hepatic enzyme GlcNAc-transferase III.

Topics: Aging; alpha-Fetoproteins; Animals; Animals, Newborn; Body Weight; Brain; Concanavalin A; Glycosides; Hyperthyroidism; Hypothyroidism; Immunoelectrophoresis, Two-Dimensional; Rats; Rats, Inbred Strains; Serum Albumin; Thyroxine