This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mayer, A. Articles by Fabien, N. Search for Related Content PubMed PubMed Citation Articles by Mayer, A. Articles by Fabien, N.

Calcium-Sensing Receptor Autoantibodies Are Relevant Markers of Acquired Hypoparathyroidism

Laboratoire d’Immunologie, Unité Fonctionnelle d’Auto-Immunité, Centre Hospitalier Lyon-Sud (C.P., A.D., A.M., J.-C.M., J.B., N.F.), 69495 Pierre-Benite, France; and Institut National de la Santé et de la Recherche Médicale, Unité 449, Faculté Laënnec (A.M., J.O., H.V.), 69008 Lyon, France

Address all correspondence and requests for reprints to: Dr. Nicole Fabien, Unité Fonctionnelle d’Auto-Immunité, Centre Hospitalier Lyon-Sud, 69495 Pierre-Benite Cedex, France. E-mail: nicole.fabien{at}chu-lyon.fr

	Abstract

Top Abstract Introduction Subjects and Methods Results Discussion References

 
We investigated the presence of autoantibodies (aAbs) directed against the parathyroid gland in 17 patients with spontaneous isolated acquired hypoparathyroidism. Fourteen patients with acquired hypoparathyroidism (AH) associated with type I or II autoimmune polyendocrinopathy syndrome were also tested in comparison with a control group of 68 subjects without AH, including patients with other autoimmune diseases and healthy blood donors. aAbs against parathyroid tissue were screened using an indirect immunofluorescence technique on primate parathyroid tissue and human parathyroid adenoma. aAbs against the calcium-sensing receptor (CaSR) were analyzed using an immunoblotting assay with the recombinant extracellular domain of the human CaSR as antigen. Seven of the 31 patients with AH were positive for CaSR aAbs. Five of the positive sera were obtained from the group with isolated AH. The two other positive sera were from patients with autoimmune polyendocrinopathy syndrome. The sensitivity of the immunoblotting technique was higher than that of both the radioimmunological test using the extracellular domain of the CaSR and the indirect immunofluorescence technique. There were no positive sera in the control group. In conclusion, using an immunoblotting assay, we demonstrate the presence of CaSR aAbs in about one third of the patients with isolated AH, pointing out the value of detecting such aAbs to assess the autoimmune origin of the disease.

	Introduction

Top Abstract Introduction Subjects and Methods Results Discussion References

 
THE PRESENCE OF autoantibodies (aAbs) against parathyroid tissue and their frequent association with other autoimmune diseases have suggested that acquired hypoparathyroidism (AH) could have an autoimmune origin (1). Hypoparathyroidism is either sporadic in adults or is one of the endocrine manifestations in type I autoimmune polyendocrinopathy syndrome (APS) (2). AH occurs in 80% of patients with type I APS, mostly in children and adolescents. Type I APS is defined by the association of at least two of the following diseases: Addison disease, hypoparathyroidism and/or chronic mucocutaneous candidiasis, alopecia, chronic active hepatitis, hypogonadism, and pernicious anemia (2). In contrast, AH is rarely observed in type II APS (3), which occurs mostly in adults. Type II APS is defined by the presence of Addison disease plus autoimmune thyroid disease and/or insulin-dependent diabetes mellitus; pernicious anemia, hypogonadism, chronic active hepatitis, and vitiligo are increased in this condition (2, 3).

The role in the pathogenesis of AH of aAbs directed against parathyroid tissue is still unclear. These aAbs have been reported to bind to the membrane of human parathyroid cells and to inhibit the secretion of PTH in vitro (4). One of their potential targets has been identified as the calcium-sensing receptor (CaSR), and the epitope is localized within the extracellular domain of the receptor (5). The CaSR was initially cloned from bovine parathyroid, allowing the sequencing of the extracellular domain of the protein (6).

The aim of the present study was to determine the sensitivity and specificity of the detection of antiparathyroid aAbs and aAbs against the CaSR (CaSR aAbs) in patients with isolated AH or AH associated with APS.

	Subjects and Methods

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Subjects

Sera from 31 patients with AH were analyzed. There were 19 males and 12 females, with a median age of 35 yr (range, 7–74 yr). Seventeen patients had isolated AH, and eight and six patients had AH associated with type I or II APS, respectively. The diagnosis of AH was based on the presence of hypocalcemia and hyperphosphatemia in association with low or subnormal levels of serum PTH. The mean duration of disease at the time of this study, i.e. the duration between the date of diagnosis and the date of sample collection, was 4.3 yr (range, 0.5–14 yr) for all AH patients and specifically 4.5 yr (range, 0.5–10 yr), 4.0 yr (range, 0.2–14 yr), and 3.9 yr (range, 0.5–8 yr) for isolated AH and AH associated with type I or II APS, respectively. Serum calcium, phosphorus, PTH, and calciuria were measured in most AH patients. All patients with type I APS suffered from AH, six had Addison disease, four had mucocutaneous candidiasis, two had autoimmune hypothyroidism, and some of them had associated clinical signs, such as alopecia, hypogonadism, vitiligo, and pernicious anemia. No chronic active hepatitis was observed in these patients. All patients with type II APS suffered from Addison disease plus autoimmune thyroid disease and insulin-dependent diabetes mellitus in two cases; some of them also suffered from vitiligo, pernicious anemia, and hypogonadism.

Control sera were obtained from four patients with postsurgery hypoparathyroidism and from 68 subjects without hypoparathyroidism, including 27 with type II APS, five with autoimmune hypothyroidism, four with type I diabetes, and 32 without autoimmune disease. The patients with AH or autoimmune diseases were recruited from the Departments of Endocrinology of Lyon, Valence, and Lille hospitals (France). The 32 individuals without AH were out-patients from other clinical departments of the Centre Hospitalier Lyon-Sud and had no evidence of autoimmune disease. All sera were kept at –80 C after serum collection that was approved by the institutional review board of the Hospices Civils de Lyon. The study was approved by the research and ethics committee of the Hospices Civils de Lyon.

Detection of aAbs against the CaSR

An immunoblotting test was performed to detect CaSR aAbs using a recombinant peptide corresponding to the extracellular domain of the protein, i.e. amino acids 1–603 (SWISS-PROT nr. P41180), which were produced in Escherichia coli (a gift from Prof. H. P. Seelig and Mrs. I. Moosbrugger, Private Institute for Immunology and Molecular Genetics, Karlsruhe, Germany). The immunoblotting technique was previously described (7). Briefly, the antigen was loaded (20 µg/lane) onto a 10% polyacrylamide gel containing 0.1% sodium dodecyl sulfate. After electrophoretic separation, the protein was transferred to a nitrocellulose membrane by electrotransfer. Nitrocellulose strips were incubated at room temperature with 1% nonfat milk in PBS to block the free protein-binding sites. Nonfat milk was chosen because this reagent reduced the background with the same efficiency as normal animal serum (data not shown). The nitrocellulose strips were then incubated with human serum or mouse monoclonal antibody to human CaSR [ADD; a gift from Drs. S. De Vries, K. Rogers, and J. Garrett, (NPS Pharmaceuticals, Salt Lake City, UT) and Drs. A. Spiegel and P. Goldsmith (Metabolic Diseases Branch, NIDDK, NIH)], diluted at 1:100 or 1:10,000 with 1% nonfat milk in PBS, respectively, for 2 h. After three washes with PBS-0.05% Tween 20, the membranes were probed with peroxidase-conjugated antihuman-IgG, IgA, IgM (H+L) (1:400; Bio-Rad Laboratories, Marnes la Coquette, France), or antimouse IgG (1/5,000; Jackson ImmunoResearch Laboratories, Inc., West Grove, PA) with 1% nonfat milk in PBS, respectively. After three washes with PBS, the antigen-antibody complexes were revealed with the peroxidase substrate (hydrogen peroxide and 4-chloro--naphtol). Serum reactivity to the CaSR was scored according to the density of the resulting color reaction. After drying, the color density of the bands was analyzed independently by three investigators. Bands that were barely visible were considered negative. Each positive serum was titrated by serial dilution until 1:3,200.

The specificity of the interaction of positive serum with the recombinant extracellular domain of the CaSR was tested in preabsorption experiments using the isolated recombinant extracellular domain of the CaSR. The preabsorption technique has been previously described (8). Briefly, the sera positive for aAbs (10 µl, diluted 1:10 in PBS) were incubated for 4 h at 37 C and for 18 h at 4 C overnight with 400 µg CaSR. The mixture was then centrifuged at 16,000 x g for 10 min, and the supernatant was diluted for a final dilution at 1:50. A sample of each serum that was not absorbed was analyzed in the same reaction. Also, positive sera were immunoblotted onto an unrelated protein, as described in a previous study (9). The antigen used in this experiment was an extract of bovine mitochondria containing a large amount of pyruvate dehydrogenase with a molecular mass of 78 kDa.

A radioimmunological test (RIA) using the extracellular domain of the CaSR was also performed in the laboratory of Prof. H. P. Seelig to detect CaSR aAbs according to the method previously described (5). Briefly, the ³⁵S-labeled recombinant peptide encompassing amino acids 1–603 of the CaSR was incubated overnight at 4 C with 5 µl patient sera. The radioactivity of the immunoprecipitated complexes using protein A-Sepharose was evaluated on a ß-scintillation analyzer. The reaction was considered positive when the result was greater than 15 arbitrary units (AU).

Detection of aAbs against parathyroid tissue

The indirect immunofluorescence (IIF) technique was performed using human parathyroid adenoma tissue obtained from three patients (a gift from Dr. N. Berger, Centre Hospitalier Lyon-Sud, Lyon, France) and monkey parathyroid tissue (The Binding Site, Grenoble, France). Frozen sections of parathyroid adenoma were air-dried, then fixed for 10 min in acetone at –20 C. Sera, at a dilution of 1:10, were incubated on cryostat sections of human or monkey parathyroid tissue for 30 min at room temperature. After three washes in PBS, pH 7.4, the sections were incubated with a fluorescein-conjugated mouse antihuman IgG (Bio-Rad Laboratories) for 30 min at room temperature.

Detection of aAbs against mitochondrial and endomysial antigens

The presence of these aAbs was tested in sera that were positive for CaSR aAbs. The tissues used were rat kidney and stomach and monkey esophagus (Bio-Rad Laboratories). Sera were diluted 1:30. The antigen-aAbs complexes were revealed using fluorescein-conjugated antihuman IgG, IgA, IgM, and IgA (Bio-Rad Laboratories), respectively. Autoantibodies directed against transglutaminase were tested with ELISA according to the instructions of the manufacturer (Pharmacia Upjohn Diagnostic, Guyancourt, France).

Statistical analysis

Statistical analysis was performed by t test and Fisher’s exact test. These tests were used to compare the frequency of CaSR aAbs positivity between patients with AH and control groups without AH and to compare the means of different biological parameters between groups with and without CaSR aAbs. P < 0.05 was considered statistically significant.

	Results

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Clinical data

Tables 1 and 2 show the clinical characteristics, serum calcium, phosphorus and PTH levels, as well as urinary calcium values of patients positive or negative for CaSR aAbs.

The immunoblotting assay was set up using the anti-CaSR mouse monoclonal antibody ADD. The protein corresponding to the extracellular domain of the CaSR migrated at the expected molecular mass of 70 kDa, and ADD showed strong reactivity with this protein (Fig. 1A). ADD was used in each experiment as a positive control. Seven of the 31 sera from patients with AH, either isolated or associated with APS, were found to react with the extracellular domain of the CaSR (Fig. 1A). Three sera were also positive for lower molecular mass proteins of 64, 49, and 46 kDa, respectively. Titration by serial dilution revealed various titers between patients with 1:100 (two cases), 1:400 (one case), 1:800 (one case), 1:1600 (one case), and 1:3200 (two cases). For two patients with multiple serum samples over time, the titer of circulating CaSR aAbs was not modified after 2 and 6 yr of follow-up.

View larger version (32K): [in this window] [in a new window]   FIG. 1. A, Immunoblottings of sera using the extracellular domain of the CaSR prepared as described in Subjects and Methods. The main reactivity was observed with a 70-kDa protein corresponding to the extracellular domain of the CaSR. Lane 1, Mouse monoclonal antibody to the CaSR (ADD); lanes 2–8, positive sera from AH; lanes 9–11, negative sera from AH; lanes 12–15, negative sera from APS type II. Molecular markers are included on the right. B and C, Experiments showing the specificity of the CaSR aAbs reactivity. B, Specific neutralization of CaSR aAbs after preincubation of the serum with the CaSR. Lane 1, Positive serum with no incubation; lane 2, positive sera after preincubation with CaSR protein; lane 3, negative sera. C, Immunoblotting of positive CaSR aAbs sera on mitochondrial antigens. Lane 1, Pyruvate dehydrogenase (molecular mass, 78 kDa) is strongly stained with a positive control containing antipyruvate dehydrogenase aAbs; lanes 2–4, positive CaSR aAbs sera were strictly negative.

The sensitivity of the immunoblotting assay was higher than that of the RIA, because only three of the seven sera that were positive by immunoblotting were positive with the radioimmunological method, with titers of 23, 45, and 115 AU, respectively. The other four sera showed titers of 1, 3, 5, and 8 AU. None of the patients had aAbs directed against mitochondrial, endomysial, or transglutaminase antigens (data not shown).

Concerning the clinical data, most (five of seven) of the sera positive for CaSR aAbs were obtained from patients with isolated AH. The others (two of seven) were from patients with AH associated with type I or II APS. The difference between the AH group and the group without hypoparathyroidism (n = 68) or with postsurgery AH (n = 4) was highly significant (P < 0.0001), because no CaSR aAbs were found in the latter two groups. Both genders (four males and three females) were represented. No age difference was observed in patients with AH who were negative (mean age, 33.6 yr; range, 10–73 yr) or positive (mean age, 40.9 yr; range, 9–73 yr) for CaSR aAbs. The mean duration of disease among the AH patients with CaSR aAbs (4.3 ± 4.1 yr) was similar to that of the AH patients negative for CaSR aAbs (3 ± 4 yr). Levels of serum calcium, serum phosphorus, serum PTH, and calciuria were also similar in both groups (Table 2).

The sera obtained from the four patients with postsurgery hypoparathyroidism and from the 68 subjects without hypoparathyroidism were all negative for CaSR aAbs (Fig. 1A).

Detection by IIF of aAbs against parathyroid tissue

Only one of the 103 sera (from the 31 patients with AH, the 68 patients without hypoparathyroidism, and the four patients with postsurgery hypoparathyroidism) that were tested for antiparathyroid aAbs was found to be positive by IIF. This serum was obtained from a patient with isolated AH. The pattern was observed as homogeneous cytoplasmic staining in the parathyroid chief cells of the primate parathyroid. No reactivity was observed within the oxyphilic cells (Fig. 2). In this patient, the same pattern of immunofluorescence was observed in all serum samples obtained during a 6-yr follow up. When detection was performed using the three different human parathyroid adenomas, we found this same serum to be positive, whereas sera from the other patients with AH remained negative. This patient found positive by IIF was one of the seven patients positive for CaSR aAbs.

View larger version (143K): [in this window] [in a new window]   FIG. 2. Detection of human antiparathyroid aAbs by an IIF technique using cryostat sections of primate parathyroid gland. Homogeneous cytoplasmic staining of the parathyroid chief cells was observed with serum from patient 1 (A). No reactivity was observed within the oxyphilic cells (white arrow). The control sera produced little or no staining (B). Magnification, x200.

None of the sera positive for CaSR aAbs showed reactivity with mitochondrial, endomysial, or transglutaminase antigens.

	Discussion

Top Abstract Introduction Subjects and Methods Results Discussion References

 
An autoimmune etiology has been suggested for acquired hypoparathyroidism (1, 2, 10, 11). However, the presence of aAbs directed against parathyroid antigens has not been well documented in this disease. The first study demonstrating such aAbs in AH was published in 1966 (1).

A second report was published 20 yr later (4), before the demonstration in 1996 of the presence of CaSR aAbs in 56% of the sera from patients with AH associated with type I APS or with autoimmune hypothyroidism (5). The aim of our study was to analyze, using a new approach, the prevalence of such CaSR aAbs in patients suffering from isolated AH as well as in those with AH associated with type I or II APS. A new immunoblotting assay was successfully set up using recombinant human extracellular CaSR, and the specificity of the test was assessed using a monoclonal antibody to the human CaSR. Seven of the 31 patients with AH were found to be positive for CaSR aAbs. The specificity of the aAbs for parathyroid antigens was carefully checked. A cross-reaction between Abs against endomysial and parathyroid antigens had, in fact, been previously reported in a case of idiopathic hypoparathyroidism with coexistent celiac disease (12). Furthermore, the pattern of immunofluorescence produced by aAbs against parathyroid tissue could be indistinguishable from that produced by antimitochondria aAbs (13). In our study, none of the positive sera showed any reactivity with mitochondrial or endomysial antigens or with transglutaminase, which are the major targets of aAbs present in celiac disease (14). The specificity of CaSR aAbs in the patients’ sera was also confirmed by neutralization experiments, and the positive sera showed no reactivity on immunoblotting using an unrelated protein of similar size to the CaSR.

The fact that only one of seven positive sera reacted under IIF, despite the use of three different adenoma tissues, suggests that CaSR aAbs cannot be efficiently detected using this technique. The discrepancy between IIF and immunoblotting may be due to recognition of different epitopes. In addition, the immunoblotting assay was more sensitive than the RIA, suggesting that CaSR aAbs can recognize either linear or conformational epitopes. In our assay, three positive sera reacted with proteins of a lower molecular mass, which may represent a portion of the extracellular domain of the CaSR and may correspond to truncated products of the recombinant antigen. Similarly, it has been reported by Li et al. (5) that CaSR aAbs can react with different epitopes of the protein.

Regarding the clinical data, five of 17 patients with isolated AH were found to be positive for CaSR aAbs. Our study and a recent report published during the submission process of the present work are the first to report the presence of CaSR aAbs in isolated AH. Such patients were not, in fact, included in the first study showing CaSR aAbs in AH (5). In the recent report by Goswami et al. (15), the prevalence of CaSR aAbs in AH was higher than in our study (49% vs. 29%), but the specificity of their assay appeared to be lower (86.7% vs. 100%). Such differences in both sensitivity and specificity could be explained by the different geographical distributions of the patients and the different detection methods for CaSR aAbs. The different prevalences could also be due to the stage of hypoparathyroidism when the study was performed. The presence of CaSR aAbs seems, in fact, to be highly dependent on disease stage, being positive immediately after the onset of AH in some cases (5). The absence of detection of CaSR aAbs can be due to delayed diagnosis of the disease and disappearance of the aAbs, as demonstrated for pancreatic aAbs in type 1 diabetes (16). However, in our study CaSR aAbs were demonstrable up to 9 yr after the onset of the disease, and two patients who were followed for 2 and 6 yr, respectively, remained positive. In addition, the mean duration of disease among the AH patients with CaSR aAbs was similar to that of the AH patients who were negative for these autoantibodies. Goswami et al. (15) reported similar findings. Finally, there was no significant difference between the groups of CaSR aAbs-positive and CaSR aAbs-negative patients with regard to male/female ratio; levels of serum calcium, serum phosphorus, or serum PTH; or calciuria.

Our data also confirm that CaSR aAbs are present in sera from patients with type I as well as type II APS (5). However, in contrast to previous findings (5), we did not observe any positive sera in patients with autoimmune hypothyroidism. Our results are in accordance with those of Goswami et al. (15).

The pathophysiological role of these CaSR aAbs needs to be further elucidated in AH. Indeed, like anti-TSH receptor aAbs (17), CaSR aAbs may play a direct role in the pathogenesis of AH by stimulating the CaSR, leading to a decrease in PTH and to hypocalcemia (4). This hypothesis was not supported by previous experiments, because CaSR aAbs did not cause activation of the CaSR expressed on HEK293 cells (5). However, this experiment requires confirmation, because it has been demonstrated that parathyroid aAbs previously described in primary hyperparathyroidism (18) played a direct role in the pathogenesis of the hypocalciuric hypercalcemia syndrome (19). Furthermore, recent data showed that patients with primary hypoparathyroidism can harbor activating antibodies to the CaSR (20).

In conclusion, our study shows that CaSR aAbs can be detected using a simple immunoblotting assay. The presence of such aAbs is of great interest in assessing the autoimmune origin of AH, especially for isolated AH not associated with other autoimmune diseases.

	Acknowledgments

 
We particularly thank Prof. H. P. Seelig and Mrs. Isabelle Moosbrugger (Private Institute for Immunology and Molecular Genetics, Karlsruhe, Germany) for the recombinant human parathyroid gland CaSR and for the detection of CaSR aAbs by RIA. We thank Drs. S. De Vries, K. Rogers, J. Garrett (NPS Pharmaceuticals, Salt Lake City, UT), A. Spiegel, and P. Goldsmith (Metabolic Diseases Branch, NIDDK, NIH) for the mouse monoclonal antibody to the calcium-sensing receptor (ADD antibody), and Dr. N. Berger (Centre Hospitalier Lyon-Sud, Lyon, France) for the human parathyroid adenoma. We also thank Drs. E. Solau-Gervais, B. Weill, S. Dubucquoi, and C. Vantyghem (Centre Hospitalier R. Salengro, Lille, France); Prof. M. Nicolino (Centre Hospitalier, Debrousse, Lyon, France); Dr. G. Chyderiotis (Laboratoire Marcel Mérieux, Lyon, France); Prof. J. C. Carrel (Centre Hospitalier Sud Francilien, Evry, France); Dr. O. Flix (Troyes, France); Dr. O. Puel (Centre Hospitalier Bordeaux, Bordeaux, France); and Dr. E. Emin-Richard (Centre Hospitalier Valence, Valence, France) for the clinical and biological data and sera of the patients.

	Footnotes

 
This work was supported by the Hospices Civils de Lyon.

A.M. and C.P. contributed equally to this work.

Abbreviations: aAb, Autoantibody; AH, acquired hypoparathyroidism; APS, autoimmune polyendocrinopathy syndrome; AU, arbitrary unit; CaSR, calcium-sensing receptor; IIF, indirect immunofluorescence.

Received January 6, 2004.

Accepted June 9, 2004.

	References

Top Abstract Introduction Subjects and Methods Results Discussion References

 

1. Blizzard RM, Chee D, Davis W 1966 The incidence of parathyroid and other antibodies in the sera of patients with idiopathic hypoparathyroidism. Clin Exp Immunol 1:119–128[Medline]
2. Neufeld M, Maclaren NK, Blizzard R 1980 Autoimmune polyglandular syndromes. Pediatr Ann 9:154–162[Medline]
3. Volpe R 1994 Autoimmune endocrinopathies: aspects of pathogenesis and the role of immune assays in investigation and management. Clin Chem 40:2132–2145[Abstract]
4. Posillico JT, Wortsman J, Srikanta S, Eisenbarth GS, Malette LE, Brown EM 1986 Parathyroid cell surface autoantibodies that inhibit parathyroid hormone secretion from dispersed human parathyroid cells. J Bone Miner Res 1:475–483[Medline]
5. Li Y, Song YH, Rais N, Connor E, Schatz D, Muir A, Maclaren N 1996 Autoantibodies to the extracellular domain of the calcium sensing receptor in patients with acquired hypoparathyroidism, J Clin Invest 4:910–914
6. Brown EM, Gamba G, Riccardi D, Lombardi M, Butters R, Kifor A, Sun A, Hediger MA, Lytton J, Hebert SC 1993 Cloning and characterization of an extracellular Ca²⁺-sensing receptor from bovine parathyroid. Nature 366:575–580[CrossRef][Medline]
7. Fabien N, Moreira A, Lavergne JP, Desbos A, Surgey P, Alves de Olivera C, Gonzalo P, Venot A, Bienvenu J, Perrier H, Reboud JP, Monier JC 1999 Autoantibodies directed against the ribosomal P proteins are not only directed against a common epitope of the P0, P1 and P2 proteins. J Autoimmun 13:103–110[CrossRef][Medline]
8. Desbos A, Gonzalo P, Monier JC, Tebib J, Reboud JP, Perrier H, Bienvenu J, Fabien N 2002 Autoantibodies directed against ribosomal proteins in systemic lupus erythematosus and rheumatoid arthritis: a comparative study. Autoimmunity 35:427–434[CrossRef][Medline]
9. Al-Hussami O, Godinot C, Monier JM, Trepo C, Monier JC 1988 Use of immunoblotting to characterize the mitochondrial antigens recognized by anti-mitochondrial autoantibodies. J Immunol Methods 113:61–73[CrossRef][Medline]
10. Ahonen P, Myllarniemi S, Sipila I, Perheentupa J 1990 Clinical variation of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) in a series of 68 patients. N Engl J Med 322:1829–1836[Abstract]
11. Tfelt-Hansen J, Schwarz P, Brown EM, Chattopadhyay N 2003 The calcium-sensing receptor in human disease. Front Biosci 8:s377–s390
12. Kumar V, Valeski JE, Wortsman J 1996 Celiac disease and hypoparathyroidism: cross-reaction of endomysial antibodies with parathyroid tissue. Clin Diagn Lab Immunol 143–146
13. Betterle C, Caretto A, Mzeviani, Pedini B, Salviati C 1985 Demonstration and characterization of anti-human mitochondria autoantibodies in idiopathic hypoparathyroidism and in other conditions. Clin Exp Immunol 62:353–360[Medline]
14. Dieterich W, Ehnis T, Bauer M, Donner P, Volta U, Riecken EO, Schuppan D 1997 Identification of tissue transglutaminase as the autoantigen of celiac disease. Nat Med 3:797–801[CrossRef][Medline]
15. Goswami R, Brown EM, Kochupillai N, Gupta N, Rani R, Kifor O, Chattopadhyay N 2004 Prevalence of calcium sensing receptor autoantibodies in patients with sporadic idiopathic hypoparathyroidism. Eur J Endocrinol 150:9–18[Abstract]
16. Hermitte L, Atlan-Gepner C, Mattei C, Dufayet D, Jannot MF, Christofilis MA, Nervi S, Vialettes B 1998 Diverging evolution of anti-GAD and anti-IA-2 antibodies in long-standing diabetes mellitus as a function of age at onset: no association with complications. Diabet Med 15:586–591[CrossRef][Medline]
17. Orgiazzi J 2000 Anti-TSH receptor antibodies in clinical practice. Endocrinol Metab Clin North Am 29:339–355[CrossRef][Medline]
18. Bjerneroth G, Juhlin C, Gudmundsson S, Rastad J, Akerström G, Klareskog L 1998 Major histocompatibility complex class II expression and parathyroid autoantibodies in primary hyperparathyroidism. Surgery 124:503–509[Medline]
19. Kifor O, Moore Jr FD, Delaney M, Garber J, Hendy GN, Butters R, Gao P, Cantor TL, Kifor I, Brown EM, Wysolmerski J 2003 A syndrome of hypocalciuric hypercalcemia caused by autoantibodies directed at the calcium-sensing receptor. J Clin Endocrinol Metab 88:60–72[Abstract/Free Full Text]
20. Kifor O, McElduff A, LeBoff MS, Moore Jr FD, Butters R, Gao P, Cantor TL, Kifor I, Brown EM 2004 Activating antibodies to the calcium-sensing receptor in two patients with autoimmune hypoparathyroidism. J Clin Endocrinol Metab 89:548–556[Abstract/Free Full Text]

This article has been cited by other articles:

				N. G. Gavalas, E. H. Kemp, K. J. E. Krohn, E. M. Brown, P. F. Watson, and A. P. Weetman The Calcium-Sensing Receptor Is a Target of Autoantibodies in Patients with Autoimmune Polyendocrine Syndrome Type 1 J. Clin. Endocrinol. Metab., June 1, 2007; 92(6): 2107 - 2114. [Abstract] [Full Text] [PDF]

				R. Goswami, R. K. Marwaha, D. Goswami, N. Gupta, D. Ray, N. Tomar, and S. Singh Prevalence of Thyroid Autoimmunity in Sporadic Idiopathic Hypoparathyroidism in Comparison to Type 1 Diabetes and Premature Ovarian Failure J. Clin. Endocrinol. Metab., November 1, 2006; 91(11): 4256 - 4259. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mayer, A. Articles by Fabien, N. Search for Related Content PubMed PubMed Citation Articles by Mayer, A. Articles by Fabien, N.