Biomedical subjects

P F Watson

Publications and source records attributed to P F Watson.

At least 19 recordsLinked to original sources

PubMed1999

Analysis of a microsatellite polymorphism of the cytotoxic T-lymphocyte antigen-4 gene in patients with vitiligo.

The CTLA-4 gene encodes a T-cell receptor that is involved in the regulation of T-cell activation. Recent studies have demonstrated an association of a microsatellite polymorphism [variant lengths of a dinucleotide (AT)n repeat] lying in exon 3 of the CTLA-4 gene, specifically a 106-bp allele, with autoimmune disorders, such as Graves' disease, autoimmune Addison's disease and autoimmune hypothyroidism. The aim of the present study was to determine whether the same polymorphism of the CTLA-4 gene was associated with vitiligo, a disorder that may have an autoimmune origin and can be present in patients who have one or more autoimmune diseases. CTLA-4 gene microsatellite polymorphisms were determined for 74 vitiligo patients (53 without any autoimmune disorder; 21 with one or more autoimmune disease) and 173 healthy controls, who had no clinical evidence of either vitiligo or any other autoimmune disorder, by polymerase chain reaction amplification of genomic DNA and resolution of the products on polyacrylamide sequencing gels. The frequency of the 106-bp allele was significantly increased (chi2 = 5. 2; P = 0.02) in vitiligo patients as a whole, in comparison with control subjects. However, when the patients were classified according to the absence or presence of an autoimmune disorder, the frequency of the 106-bp allele was significantly increased (chi2 = 14.8; P = 0.0001) only in the group of vitiligo patients who also had an autoimmune disease. However, the fact that 17 of 21 patients also had either autoimmune thyroiditis or autoimmune Addison's disease probably accounts for the apparent association of vitiligo and the 106-bp allele in this patient group. However, it was found that the relative risk of 3.2, conferred by the 106-bp allele in this group of vitiligo patients, was greater than that found for patients with only either Graves' disease, autoimmune hypothyroidism or autoimmune Addison's disease, with values of 2.1, 2.2 and 2.2, respectively. For the group of patients without an autoimmune disorder, there was no significant difference (chi2 = 0.2; P = 0.64) in the frequency of the 106-bp allele when compared with control subjects. These results indicate that there is no association between the 106-bp allele and vitiligo, at least when the disorder occurs in the absence of an autoimmune disease.

Abatacept↗

PubMed1999

Identification of epitopes on tyrosinase which are recognized by autoantibodies from patients with vitiligo.

The identification of tyrosinase autoantibodies in some patients with vitiligo has previously been reported. In this study we have determined the B cell epitopes on tyrosinase which are recognized by these autoantibodies. Deletion derivatives of tyrosinase cDNA were constructed and then translated in vitro with the concomitant incorporation of [35S]methionine into the protein products. The 35S-labeled tyrosinase derivatives were subsequently used in radioimmunoassays to investigate the reactivity of sera from five vitiligo patients. The epitope regions identified were: three in a central region of tyrosinase (amino acids 240-255, 289-294, and 295-300) and two others towards the C-terminal end of the protein (amino acids 435-447 and 461-479). Computer analysis of the potential B cell epitopes on tyrosinase revealed that the epitope regions recognized by the vitiligo sera were located in areas predicted to be highly antigenic. In addition, the centrally located antigenic regions (amino acids 289-294 and 295-300) had amino acid sequence homology to both tyrosinase-related protein-1 and -2. Thus, the epitopes on tyrosinase recognized by vitiligo patient sera are heterogeneous and include a region with homology to two related proteins which may explain the cross-reactivity previously noted between these antigens.

Adult↗

PubMed1999

Sperm-oviduct interaction: induction of capacitation and preferential binding of uncapacitated spermatozoa to oviductal epithelial cells in porcine species.

After mating, inseminated spermatozoa are transported to the oviduct. They attach to and interact with oviductal epithelial cells (OEC). To investigate sperm-OEC interactions, we used chlortetracycline to study the capacitation status of boar spermatozoa in coculture with homologous OEC and cells of nonreproductive origin (LLC-PK1, porcine kidney epithelial cell line). Boar spermatozoa were cocultured with OEC and LLC-PK1 cells for 15, 60, 120, or 240 min. The proportion of capacitated spermatozoa in coculture with the isthmic and ampullar cells increased significantly (p < 0.05) during incubation. However, most spermatozoa in coculture with LLC-PK1 cells or blank (medium only) remained uncapacitated. In addition, preferential binding of uncapacitated, capacitated, or acrosome-reacted boar spermatozoa to OEC and the other cell type was investigated. Our approach was to vary the proportions of uncapacitated, capacitated, or acrosome-reacted boar spermatozoa in suspension using long preincubation and lysophosphatidylcholine treatment of semen prior to a very short incubation with OEC or LLC-PK1 cells. The results showed that the majority of spermatozoa that were bound to OEC or LLC-PK1 cells were uncapacitated and that a significant relationship existed between the relative proportion of uncapacitated spermatozoa in the control samples and those bound to LLC-PK1 cells (r2 = 0.43, p < 0.005). However, there was no correlation between the proportion of uncapacitated spermatozoa in the control samples and the proportion of those bound to isthmic or ampullar cells. In conclusion, the results clearly demonstrated the specific nature of the sperm-OEC interaction in the porcine species. This interaction is initiated by uncapacitated spermatozoa binding to OEC and is continued by the induction of capacitation in cocultured spermatozoa.

Animals↗

PubMed1998

Autoantibodies to tyrosinase-related protein-1 detected in the sera of vitiligo patients using a quantitative radiobinding assay.

In the present study, we describe the in vitro transcription-translation of human tyrosinase-related protein-1 (TRP-1) cDNA and subsequent use of the resulting 35S-labelled TRP-1 in a radioimmunoassay to analyse vitiligo sera for the presence of TRP-1 antibodies. Of 53 vitiligo sera examined in the assay, three (5.7%) were found to be positive for TRP-1 antibodies. In contrast, sera from 20 controls, 10 patients with Hashimoto's thyroiditis and 10 patients with Graves' disease were all negative for TRP-1 antibodies. Although glycosylation of the labelled protein was necessary for its immunoprecipitation by TRP-1-specific monoclonal antibody TA99, this post-translational processing did not affect the binding of any of the sera tested. All three patients positive for TRP-1 antibodies (aged 50-63 years) had had vitiligo of the symmetrical type for more than 1 year, and all of them also had an associated autoimmune disorder: Graves' disease in one and autoimmune hypothyroidism in two. In addition, antibodies to the melanogenic enzymes tyrosinase and tyrosinase-related protein-2 (TRP-2) were present in their serum. Absorption studies indicated that preincubation with COS-7 cell extract containing either expressed TRP-1, tyrosinase or TRP-2 absorbed out the immunoreactivity of the three sera positive in the radioimmunoassay (RIA) with [35S]TRP-1. The results indicate that autoantibodies to TRP-1 cross-react with tyrosinase and TRP-2, suggesting one or more common epitopes between the three proteins.

Adolescent↗

PubMed1998

Autoantibodies to human melanocyte-specific protein pmel17 in the sera of vitiligo patients: a sensitive and quantitative radioimmunoassay (RIA).

In the present study we describe the in vitro transcription-translation of human melanocyte-specific protein Pmel17 cDNA and subsequent use of the resulting 35S-labelled Pmel17 in an RIA to analyse vitiligo sera for the presence of Pmel17 antibodies. Of 53 vitiligo sera examined in the assay, three (5.9%) were found to be positive for Pmel17 antibodies. In contrast, sera from 20 healthy controls, 10 patients with Hashimoto's thyroiditis and 10 patients with Graves' disease (GD) were all negative for Pmel17 antibodies. All three patients positive for Pmel17 antibodies (aged 50-63 years) had had vitiligo of the symmetrical type for > 1 year and all of them also had an associated autoimmune disorder: GD in one and autoimmune hypothyroidism in two. In addition, all three patients had antibodies to the melanogenic enzymes tyrosinase, tyrosinase-related protein-1 (TRP-1) and tyrosinase-related protein-2 (TRP-2) in their serum. Absorption studies indicated that preincubation with COS-7 cell extract containing expressed Pmel17 absorbed out the immunoreactivity of the three sera positive in the RIA, confirming the anti-Pmel17 reactivity of the sera from these patients. In contrast, COS-7 cell extracts containing either expressed tyrosinase, TRP-1 or TRP-2 did not remove the anti-Pmel17 reactivity of the three sera in the RIA. This lack of cross-reactivity suggests that the humoral response to Pmel17 in these patients is specific and independent of the antibody reactivity to tyrosinase, TRP-1 and TRP-2.

Absorption↗

PubMed1998

A study of the association between a polymorphism in the CTLA-4 gene and postpartum thyroiditis.

OBJECTIVE: Postpartum thyroiditis (PPT) is an autoimmune thyroid disease which shares immunological and clinical features with autoimmune hypothyroidism and Graves' disease, and is believed to be caused by a combination of genetic and environmental factors. Recently, an association has been described between Graves' disease or autoimmune hypothyroidism and a polymorphism in the CTLA-4 gene, which encodes a T cell receptor for the B7 family of ligands, and we wished to test whether a similar association exists with PPT. DESIGN: A population-based case-control study of a CTLA-4 gene microsatellite polymorphism was performed, to look for an association with PPT. PATIENTS: Caucasoid women (n = 122) were studied; 58 had thyroid antibodies (against thyroglobulin or thyroid peroxidase) alone during the postpartum period (PPT-) and 64 had thyroid antibodies and some form of postpartum thyroid dysfunction (PPT+). RESULTS: There was no significant difference between this whole group of women and 161 local Caucasoid thyroid antibody-negative women for the CTLA-4106 base pair (AT)n microsatellite polymorphism (relative risk = 1.3; P = 0.3), nor did the PPT+ group differ from controls when analysed separately (P = 0.2). When the postpartum women were subdivided in groups according to clinical pattern of PPT and the type of thyroid antibodies, there were no associations within the subgroups. CONCLUSIONS: No significant association exists between postpartum thyroiditis and a polymorphism in the CTLA-4 gene. Furthermore, a natural variation in the prevalence of the polymorphism in healthy UK populations underscores the need to select appropriately matched normal subjects in future case-control studies.

Abatacept↗

PubMed1998

Regulation and tissue distribution of the human sodium iodide symporter gene.

OBJECTIVE: Iodide uptake by the thyroid gland is mediated by the sodium iodide symporter (NIS). In the present report, we have analysed the factors that modulate human NIS mRNA expression and iodide uptake in primary thyroid follicular cell (TFC) cultures. In addition, NIS mRNA tissue distribution was investigated. METHODS: Primary thyroid follicular cell cultures were treated with human recombinant TSH with or without cytokines for 72 h. Subsequently, NIS gene expression and iodide uptake were analysed using reverse transcription-polymerase chain reaction (RT-PCR) and 125I uptake, respectively. Human tissue samples were investigated for NIS gene expression using both RT-PCR and Northern blotting. RESULTS: Human TSH increased both NIS gene expression and iodide uptake in TFC cultures in a dose-dependent manner. Using concentrations of 0.1 U/l of hTSH, a minor increase in NIS gene expression was detected without a detectable increase in iodide uptake. IL-1 alpha, TNF alpha and IFN gamma at concentrations of 10(5) U/l all inhibited TSH-induced NIS gene expression and iodide uptake. In these experiments, there was a good correlation between NIS mRNA expression and iodide uptake. Using RT-PCR higher levels of NIS mRNA were detected in Graves' disease (GD) compared to multi-nodular goitre tissue samples. Stomach and salivary gland tissue also expressed NIS mRNA, whereas low levels were found in the mammary gland and extraocular muscle tissue. No expression was detected in the ovary, oesophagus, colon, extraocular fat or skin. In contrast, Northern blot analysis failed to detect NIS in stomach, salivary gland, intestinal fat or non-toxic multi-nodular goitre tissue samples, although this was present in GD thyroid tissue. CONCLUSION: TSH upregulates sodium iodide symporter gene expression and iodide uptake in primary thyroid follicular cell cultures, and this induction is modulated by cytokines. Variable levels of sodium iodide symporter mRNA are present in different tissue samples, with high expression evident in Graves' disease thyroid tissue.

Actins↗

PubMed1998

A cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphism is associated with autoimmune Addison's disease in English patients.

OBJECTIVE: Recent studies have demonstrated an association between a microsatellite polymorphism of the CTLA-4 gene, specifically a 106 base pair allele, and both Graves' disease and autoimmune hypothyroidism. The aim of the present study was to determine whether the same polymorphism of the CTLA-4 gene was associated with autoimmune Addison's disease. DESIGN AND PATIENTS: We analysed a microsatellite polymorphism (variant lengths of a dinucleotide (AT)n repeat) within exon 3 of the CTLA-4 gene in the following groups: 21 English patients with non-associated Addison's disease, 18 with autoimmune polyglandular syndrome type 2 (APS2) and 173 healthy control subjects; 26 Norwegian patients with non-associated Addison's disease, 9 with autoimmune polyglandular syndrome type 1 (APS1), 17 with APS2 and 100 controls; 3 Finnish patients with non-associated Addison's disease, 5 with APS2 and 71 controls; 10 Estonian patients with non-associated Addison's disease, 2 with APS2 and 45 controls. MEASUREMENTS: The CTLA-4 microsatellite gene polymorphisms were determined by polymerase chain reaction amplification of genomic DNA and resolution of the products on sequencing gels. RESULTS: The frequency of the 106 base pair allele was significantly increased in the groups of English patients with either non-associated Addison's disease or APS2 (P = 0.02 and 0.04, respectively), when compared to healthy controls with no clinical evidence or family history of either Addison's disease or any other autoimmune disorder. For Norwegian patients with either non-associated Addison's disease, APS1 or APS2, there was no association (P = 0.69, 0.62 and 0.97, respectively). This was also the case for Finnish patients with either non-associated Addison's disease or APS2 (P = 0.23 and 0.28, respectively) and for Estonian patients with either non-associated Addison's disease or APS2 (P = 0.34 and 0.29, respectively). CONCLUSIONS: These results indicate that differences exist in the frequency of the 106 base pair allele in different population groups and in only the English population was the 106 base pair allele associated with Addison's disease.

Abatacept↗

PubMed1998

A new chemiluminescent assay for the rapid detection of thyroid stimulating antibodies in Graves' disease.

OBJECTIVE: Thyroid stimulating antibodies (TSAb) are the cause of Graves' disease (GD). At present, these antibodies can only be measured using bioassays, which are generally time consuming and difficult to apply to whole serum. Here we describe a new chemiluminescent assay for the detection of TSAb in serum samples. METHODS: A Chinese hamster ovary (CHO) cell line, stably transformed with a reporter plasmid containing the firefly luciferase gene under the transcriptional control of multiple cAMP responsive elements (CRE), was transfected with the human thyroid stimulating hormone (TSH) receptor. A clonal cell line, (NA-4), was obtained which showed a dose-dependent increase in luciferase activity in response to bovine and human TSH stimulation. NA-4 was subsequently used to study TSAb activity in 42 GD sera. RESULTS: Of the GD sera 25 (60%) produced an increase in luciferase activity of 1.4-9 fold that obtained with control sera. Results were compared with an established bioassay for TSAb, based on the direct measurement of intracellular cAMP, and there was a significant correlation between the two assays (r = 0.8; P < 0.0001). IgG from GD patients, but not controls, also increased luciferase activity in NA-4 cells using concentrations as low as 3 mg/l in selected samples. CONCLUSION: The present report describes a simple, sensitive and rapid assay for the detection of TSAb, with application both in the clinical analysis of GD patient sera and as a potential research tool for use in the isolation of TSAb monoclonal antibodies.

Animals↗

PubMed1998

Comparative mapping of cloned human and murine antithyroglobulin antibodies: recognition by human antibodies of an immunodominant region.

Antibodies (Ab) to thyroglobulin (Tg) are common in patients with autoimmune thyroid diseases, but it is currently unclear how Tg Ab are involved in the pathology of autoimmune thyroid disease. We have previously reported the isolation of immunoglobulin G (IgG)kappa and IgGlambda Fab from phage display combinatorial libraries from the cervical lymph node of a single Hashimoto's thyroiditis patient with a high anti-Tg titer. Sequence analysis of these Fab indicated a restricted heavy chain usage with a nonrestricted light chain usage, with Fab inhibiting the binding of patient Tg Ab by between 39% and 79%. Comparative mapping of nine each of these IgGkappa and IgGlambda Fab, and the patient serum from whom the Fab were derived, is described here, using a panel of 10 murine monoclonal antibodies (Mab) to human thyroglobulin (hTg). The Fab interacted principally with mAb defining the overlapping antigenic domains I and IV, previously characterized as the region recognized by the majority of patient serum Tg Ab. Tg Ab from serum of the patient from whom the Fab were derived were also directed at this region, suggesting that the Fab are representative of the Tg Ab present in this patient.

Animals↗

PubMed1998

Analysis of the T-cell receptor Valpha repertoire and cytokine gene expression in Sjögren's syndrome.

The antigen receptor diversity of pathogenic T cells in Sjögren's syndrome (SS) may have important implications in the development of the disease; cytokines from these cells and other sources also play a role in the pathogenesis of this disease. Using a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) technique, we have attempted to correlate the presence of restriction in the T-cell receptor (TCR) repertoire with cytokine profiles. We have analysed TCR V alpha family usage, and the expression of interleukin-1alpha (IL-1alpha), IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-13, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha), in labial biopsies from 12 patients with SS and compared these with samples from three patients with chronic sialadenitis (CS). Only one of the SS biopsies showed evidence of V alpha restriction (three out of 18 gene families). Apart from this, expression patterns were similar in both patient groups. Four of the 12 SS samples demonstrated a 'limited heterogeneity' of the V alpha repertoire with 3-4 families predominantly expressed, in particular V alpha1 and V alpha3. Peripheral blood lymphocytes were unrestricted. The cytokine profiles of the SS and CS biopsies were generally similar. However both IFN-gamma and IL-1alpha were absent from CS, but present in SS samples. The expression of IFN-gamma in the majority of the samples, together with a lack of IL-4 and IL-13 mRNA, suggests the predominance of a Th1 response in SS. There was no clear association between the repertoire of V alpha genes expressed and the cytokine profile observed. However, the V alpha restriction in one SS sample did correspond with a limited diversity of cytokines detected.

Adult↗

PubMed1998

The modulation of the human sodium iodide symporter activity by Graves' disease sera.

The transport of iodide into the thyroid, catalyzed by the Na+/I- symporter (NIS), is the initial and rate-limiting step in the formation of thyroid hormones. To study the basic characteristics of the human (h) NIS, we have established a Chinese hamster ovary cell line stably expressing the hNIS (CHO-NIS9). In agreement with previous work on the rat NIS, iodide uptake in these cells was initiated within 2 min of the addition of 131I, reaching a plateau after 30 min. Both perchlorate and thiocyanate inhibited iodide uptake in a dose-dependent manner, with inhibition evident at concentrations of 0.01 and 0.1 micromol/L, respectively, and reaching complete inhibition at 20 micromol/L and 500 micromol/L, respectively. Ouabain, which blocks the activity of the Na+/K+ adenosine triphosphatase, also inhibited iodide uptake in a dose-dependent manner, starting at concentrations of 100 micromol/L and reaching maximum inhibition at 1600 micromol/L, indicating that iodide uptake in these cells is sodium dependent. CHO-NIS9 cells were further used to study 88 sera from patients with Graves' disease, for iodide uptake inhibitory activity, which were compared with sera from 31 controls. Significant iodide uptake inhibition was taken as any inhibition in excess of the mean + 3 SD of the results with the control sera. On this basis, 27 (30.7%) of the Graves' sera, but none of the controls, inhibited iodide uptake in CHO-NIS9. IgGs from these patients also inhibited iodide uptake, indicating that this inhibitory activity was antibody mediated. In summary, we have established a CHO cell line stably expressing the hNIS and shown that antibodies in GD sera can inhibit iodide uptake in these cells. This further emphasizes the role of NIS as a novel autoantigen in thyroid immunity.

Animals↗

PubMed1998

The sodium iodide symporter gene and its regulation by cytokines found in autoimmunity.

Iodide concentration by the thyroid gland, an essential step for thyroid hormone synthesis, is mediated by the Na+/I- symporter (NIS). To identify factors that may regulate this process, we have studied NIS gene expression in the Fisher rat thyroid cell line (FRTL-5) by a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) technique. Increasing concentrations of bovine TSH (0.1, 1, 10, 50 and 100 mU/l), with or without tumour necrosis factor-alpha (TNF alpha), interferon-gamma (IFN gamma) or interleukin-1 alpha (IL-1 alpha) were added to FRTL-5 cells previously deprived of TSH for a minimum of 5 days. RNA was extracted and samples were studied for NIS expression. TSH enhanced NIS mRNA expression in a dose-dependent manner, with induction evident at 0.1 mU/l, reaching a peak at 50 mU/l, an effect detected after 6 h of stimulation, but not in the first 2 h. Both TNF alpha and, to a lesser extent, IL-1 alpha inhibited basal and TSH-induced NIS expression. High concentrations of IFN gamma also downregulated TSH-stimulated NIS mRNA expression. Using the same technique, we also investigated NIS mRNA tissue distribution in two male and one female Wistar rats. High levels of NIS expression were detected in the thyroid, stomach, and mammary gland, lower levels were found in the intestine, adipose tissue and liver, borderline levels were expressed in the salivary gland, and no expression was detected in the kidneys. In summary, we have shown that TSH upregulates rat NIS gene expression in vitro, and this induction can be modulated by cytokines. Analysis of the distribution of rat NIS mRNA ex vivo demonstrated variable levels of NIS transcription in different tissue samples.

Adipose Tissue↗

PubMed1997

Simultaneous detection of the acrosomal status and viability of incubated ram spermatozoa using fluorescent markers.

Incubation of diluted ram spermatozoa at 39 degrees C results in a high percentage of acrosome reactions, but previously we have not been able to demonstrate the viability of these cells. Detection of the viability and stages of acrosomal exocytosis, either spontaneous or induced, was carried out using fluorescent probes. Propidium iodide (PI) was used to determine cell viability and, simultaneously, FITC-Pisum sativum lectin (FITC-PSA) was used to assess acrosomal status by staining glycoproteins in the acrosome of permeabilised spermatozoa. Diluted ram semen was incubated for 6 hours at 39 degrees C. At 2 hourly intervals, samples were taken and examined for evidence of a spontaneous acrosome reaction. In addition, calcium ionophore A23187 was used to induce the acrosome reaction and samples were examined at 10 minute intervals. PI was added and then washed out by filtration. Smears were made and air-dried, permeabilised with absolute ethanol and then stained with FITC-PSA. The slides were later viewed under the fluorescence microscope with a peak excitation wavelength of 488 nm. With this combination of two fluorescent probes using a single excitation wavelength, both the cell viability and the acrosomal status could be simultaneously and easily visualized. Results showed four categories of staining: PI-ve/PSA + ve (Live and acrosome-intact), PI + ve/PSA + ve (dead and acrosome-intact), PI - ve/PSA - ve (live and acrosome-reacted) and PI + ve/PSA - ve (dead and acrosome-degenerated). About 75% spermatozoa that were acrosome-reacted were still viable after 4 h incubation in the absence of ionophore, and approximately 90% spermatozoa were acrosome-reacted and still viable after 30 min incubation in the presence of ionophore.

Acrosome↗

PubMed1997

The potential transmission of infectious agents by semen packaging during storage for artificial insemination.

Plastic straws, of a type widely used for semen cryopreservation, sealed using three different methods, (PVA powder, plastic spheres and plasticine modelling clay) were tested for leakage of low molecular weight dye (methylene blue), bacteria (Escherichia coli) and virus (Newcastle disease virus). Leakage was found to be dependent on the method used to fill the straws. Straws filled using a traditional 'dip and wipe' method and sealed with PVA powder demonstrated a significant degree of methylene blue leakage (0.0269% of the total straw contents) probably associated with contamination of the powder sealing plug. Straws filled using an aseptic filling technique showed no detectable leakage of any agent with any of the sealing methods. This study highlights the need to establish good-practice guidelines for the packaging of semen collected for freezing and future AI from non-domestic livestock where disease-free status cannot be guaranteed and unsophisticated technology is used.

Animals↗

PubMed1997

Cytokines and Graves' disease.

Cytokines are an extraordinarily diverse group of molecules, with pleiotropic and often overlapping effects. They are crucial to the autoimmune response, and, in particular, regulation of CD4+ and CD8+ T-cell function depends on the balance of cytokines produced during an immune response. It is also now clear that cytokines are produced by a wide array of cells, including the thyroid follicular cells (TFCs). Intrathyroidal lymphocytes produce a heterogeneous pattern of cytokines and we have summarized the likely effects of these. In Graves' disease, TFCs can themselves express immunologically important molecules as the result of cytokine stimulation and these could contribute to the perpetuation of the autoimmune process. In addition, cytokines have a number of generally inhibitory effects on thyroid hormone production which would tend to counter the stimulatory effects of thyroid-stimulating hormone receptor antibodies in Graves' disease.

Antibody Formation↗

PubMed1997

Immunoprecipitation of melanogenic enzyme autoantigens with vitiligo sera: evidence for cross-reactive autoantibodies to tyrosinase and tyrosinase-related protein-2 (TRP-2).

In the present study we describe the detection of TRP-2 antibodies in vitiligo patients using in vitro 35S-labelled human TRP-2 in a radioimmunoassay. Of 53 vitiligo sera examined in the assay, three (5 9%) were found to be positive for TRP-2 antibodies. In contrast, 20 control sera, sera from 10 patients with Hashimoto's thyroiditis and sera from 10 patients with Graves' disease were all negative. All three patients positive for TRP-2 antibodies (mean age 54 years, age range 50-63 years) had had vitiligo of the symmetrical type for more than 1 year and all of them also had an associated autoimmune disorder: Graves' disease in one and autoimmune hypothyroidism in two. In addition, antibodies to the melanogenic enzyme tyrosinase were present in their serum. To examine any immunological cross-reactivity between TRP-2 and tyrosinase, the three vitiligo sera positive for TRP-2 antibodies were preabsorbed with COS-7 cell extract containing either expressed TRP-2 or tyrosinase, and subsequently used in the radioimmunoassay. These absorption studies indicated that preincubation with both proteins inhibited the immunoreactivity of the positive sera in the immunoassay using in vitro translated 35S-TRP-2. This antibody cross-reactivity suggests the humoral response to the two melanogenic enzymes in these patients may not be entirely independent.

Absorption↗

PubMed1997

A CTLA-4 gene polymorphism is associated with both Graves disease and autoimmune hypothyroidism.

OBJECTIVE: The autoimmune thyroid diseases, Graves disease and autoimmune hypothyroidism, result from a complex interaction between genetic, environmental and endogenous factors. The genetic loci conferring susceptibility remain unclear. A recent report has demonstrated an association between a microsatellite polymorphism of the CTLA-4 gene (allele 106) on chromosome 2q33 and Graves' disease in Caucasian patients in the USA. The aim of the present study was to confirm this association in UK patients and to determine whether this polymorphism is also associated with autoimmune hypothyroidism. DESIGN: Analysis of Caucasian patients with autoimmune thyroid disease from a single clinic, compared to local Caucasian controls. PATIENTS: We studied 112 patients with Graves' disease, 44 with autoimmune hypothyroidism and 91 controls. MEASUREMENTS: CTLA-4 microsatellite gene polymorphisms were determined by polymerase chain reaction amplification of genomic DNA and resolution of the products on sequencing gels. RESULTS: As in previous studies, 21 alleles of the CTLA-4 microsatellite region were detected. Allele 106 was significantly increased in patients with Graves' disease (P = 0.006) and in those with autoimmune hypothyroidism (P = 0.02) when compared to controls. There was no significant difference between the groups in the distribution of the other alleles and no association between allele 106 and sex, HLA-DR or -DQ specificities or the presence of ophthalmopathy in the Graves' patients. CONCLUSIONS: These results confirm that the CTLA-4 gene, or one closely associated with it, confers susceptibility to Grave's disease but is not specific as the CTLA-4 106 allele is also associated with autoimmune hypothyroidism. This association seems to be with autoimmune thyroid disease in general.

Abatacept↗