Tryptophan hydroxylase autoantibodies as markers of a distinct autoimmune gastrointestinal component of autoimmune polyendocrine syndrome type 1.

BACKGROUND: Autoantibodies to tryptophan hydroxylase (TPHAbs) directed against serotonin-producing enterochromaffin cells (EC) have been reported in autoimmune-polyendocrine-syndrome type 1 (APS-1) patients with gastrointestinal dysfunction (GID). Serotonin plays a critical role in enteric function and its peripheral blood levels reflect serotonin release from the gastrointestinal tract. AIMS: We test the hypothesis that TPHAbs mark a distinct autoimmune component of APS-1 characterized by an autoimmune attack toward EC, which results in clinical GID. METHODS: TPHAbs were measured in 64 APS-1 patients. Endoscopy with gastric (antrum/body) and duodenal biopsy was carried in 16 TPHAbs+ patients (8 with and 8 without GID) and in 2 TPHAbs- patients (without GID). Immunohistochemistry of biopsy specimens was carried out using antibodies to serotonin, chromogranin-A, CD3, CD4, CD8, and CD20. Serotonin serum levels were measured in TPHAbs+ and TPHAbs- patients who had endoscopy. RESULTS: Thirty-seven of 64 patients were TPHAbs+ (11/12 with GID and 26/52 without GID; P < .001). Gastric and duodenal biopsies in all 8 TPHAb+ patients with GID showed lymphocytic infiltration with increased CD3+CD8+ intraepithelial lymphocytes and absence of EC. Furthermore, mean serotonin serum levels were below the normal range in TPHAb+ patients with GID (P < .01). In 8 TPHAb+ patients without GID gastric and duodenal biopsies showed different grades of inflammatory infiltration and reduced number of EC. Mean serotonin serum levels were near the lower limit of the normal range. In all TPHAbs+ patients the biopsies showed a reduced number of chromogranin-A positive cells consistent with enteroendocrine cells depletion. TPHAbs- patients without GID showed normal gastrointestinal mucosa and serotonin serum levels. CONCLUSIONS: TPHAbs appear to be markers of a distinct autoimmune component of APS-1. Progressive involvement of the gastrointestinal EC leads to the transition from preclinical to clinical disease, characterized by GID and reduced serotonin serum levels.

Premature ovarian failure in patients with autoimmune Addison's disease: clinical, genetic, and immunological evaluation.

DESIGN: The design of the study was to investigate the prevalence of the following: 1) premature ovarian failure (POF) in patients with autoimmune Addison's disease (AD); 2) steroid-producing cell antibodies (StCA) and steroidogenic enzymes (17α-hydroxylase autoantibodies and P450 side-chain cleavage enzyme autoantibodies) in patients with or without POF; and 3) the value of these autoantibodies to predict POF. PATIENTS: The study included 258 women: 163 with autoimmune polyendocrine syndrome type 2 (APS-2), 49 with APS-1, 18 with APS-4, and 28 with isolated AD. METHODS: StCA were measured by an immunofluorescence technique and 17α-hydroxylase autoantibodies and P450 side-chain cleavage enzyme autoantibodies by immunoprecipitation assays. RESULTS: Fifty-two of 258 women with AD (20.2%) had POF. POF was diagnosed in 20 of 49 (40.8%) with APS-1, six of 18 (33.3%) with APS-4, 26 of 163 (16%) with APS-2, and none of 28 with isolated AD. In patients with APS-1 and APS-4, POF developed after AD, whereas it preceded AD in patients with APS-2. StCA were detected in 31 of 43 with POF (72%) and 51 of 198 without POF (25.7%). StCA were present in 22 of 38 with APS-1 (57.9%) (11 of 13 with POF); in five of 13 with APS-4 (38.5%) (three of four with POF); in 53 of 162 with APS-2 (32.7%) (17 of 26 with POF), and in one of 28 isolated AD patients (3.6%). Twelve of 13 patients with POF with a duration less than 5 yr (92.3%) and 18 of 25 with duration longer than 5 yr (72%) were StCA positive. Twenty-eight of 31 with POF (90.3%) were positive for at least one steroidogenic antibody. Forty-one women with AD less than 40 yr were followed up for a mean period of 9 yr. Eight of 21 women (38%) positive or seroconverted for steroidogenic autoantibodies developed POF at a mean age of 23 yr (six with APS-1, one with APS-2, and one with APS-4), and none of the 20 patients negative for steroidogenic autoantibodies developed POF. CONCLUSIONS: This study indicates that AD is frequently associated with POF and that steroidogenic antibodies are markers of patients with POF. Steroidogenic autoantibodies are predictive markers of POF in patients with AD.

Preparation and testing of diabetes autoantibody controls.

Stocks of the WHO islet cell antibody, GAD(65) antibody, and IA-2 antibody standard (NIBSC 97/550) are now very limited. We have therefore made and tested a series of control preparations in which human monoclonal autoantibodies to IA-2 and to GAD(65) were diluted in antibody-negative human serum to different concentrations. Three different diabetes autoantibody controls (DAC 1-3) were made as was a negative control preparation. Aliquots containing 1 mL of autoantibodies in serum were freeze-dried. After reconstitution (with 1 mL of water) the controls were tested by (125)I-IA-2 immunoprecipitation assay (IPA), (125)I-GAD(65) IPA, GAD(65) Ab ELISA and IA-2 Ab ELISA (kits from RSR Ltd.) and for ICA by immunofluorescence test (IFT). DAC1 is particularly suitable as a control for the (125)I IA-2 IPA; DAC2 is suitable for the (125)I-GAD(65) IPA, GAD(65) Ab ELISA, and IA-2 Ab ELISA; and DAC3 is suitable for the ICA IFT. Freeze-dried preparations showed good stability at 37 degrees C. Reconstituted liquid preparations were stable when stored at 4 degrees C and at 37 degrees C. Availability of an essentially unlimited supply of these reagents should be useful in establishing reproducible and comparable measurements of diabetes autoantibodies in different laboratories using different assays.

Effects of a thyroid-stimulating human monoclonal autoantibody (M22) on functional activity of LH and FSH receptors.

OBJECTIVE: The glycoprotein hormones luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyrotropin (TSH) show low-level cross-reactivity between their respective receptors (R). Patient serum autoantibodies to the thyrotropin receptor (TSHR) do not appear to cross-react with the luteinizing hormone receptor (LHR) or follicle-stimulating hormone receptor (FSHR), although the concentrations of autoantibody with which it is feasible to carry out experiments of this type are limited. Consequently, we have studied the effects of high doses of the thyroid-stimulating human monoclonal autoantibody (M22) on the LHR and FSHR. DESIGN: Chinese Hamster ovary (CHO) cells stably expressing the TSHR, LHR, and FSHR and purified M22 IgG preparations were used in the study. METHODS: CHO-TSHR, CHO-LHR, and CHO-FSHR cells were incubated with bovine TSH (0.1-25mU/mL), human recombinant chorionic gonadotropin (hCG; 0.5-10mU/mL) or human recombinant FSH (100-5000mU/mL) or with M22 IgG (0.001-5.0 microg/mL), and the extracellular cyclic AMP was measured by radioimmunoassay. RESULTS: Cyclic AMP levels increased in a dose-dependent manner after incubation of CHO-TSHR cells with TSH or M22 IgG, and on a molar basis the effects of TSH and M22 were similar. Cyclic AMP stimulation was not detectable in CHO-LHR and CHO-FSHR cells after incubation with M22 IgG, whereas incubation with hCG or FSH, respectively, caused dose-dependent cyclic AMP stimulation. On a molar basis, concentrations of M22 IgG approximately 100x those of FSH causing clear stimulation were ineffective with CHO-FSHR cells. Similarly, molar concentration of M22 IgG 20,000x those of hCG causing clear stimulation had no effect on CHO-LHR cells. CONCLUSIONS: This study shows that at relatively high concentrations, M22 IgG is unable to stimulate cyclic AMP levels in CHO-LHR or CHO-FSHR cells, suggesting that TSHR autoantibodies have greater specificity for the TSHR than TSH itself.

Autoimmune oophoritis as a mechanism of follicular dysfunction in women with 46,XX spontaneous premature ovarian failure.

OBJECTIVE: To assess the association between serum adrenal cortex autoantibodies and histologically confirmed autoimmune lymphocytic oophoritis. DESIGN: Controlled, prospective. SETTING: Tertiary research center. PATIENT(S): Two hundred sixty-six women with 46,XX spontaneous premature ovarian failure. INTERVENTION(S): Ovarian biopsy in 10 women. MAIN OUTCOME MEASURE(S): Serum adrenal cortex autoantibodies assessed by indirect immunofluorescence and autoimmune oophoritis assessed by immunohistochemical lymphocyte markers. RESULT(S): We obtained a histologic diagnosis of autoimmune oophoritis in four women who tested positive for adrenal cortex autoantibodies and excluded this diagnosis in ovarian biopsies from six women who tested negative for adrenal cortex autoantibodies (4/4 vs. 0/6). Women with histologically confirmed autoimmune oophoritis had a greater total ovarian volume as assessed by transvaginal sonography (11.4 +/- 5.6 mL vs. 1.5 +/- 0.4 mL) (mean +/- SEM). They were also more likely to have subclinical adrenal insufficiency and clinical signs of androgen deficiency (3/4 vs. 0/6). Overall, 10/266 women tested positive for adrenal cortex autoantibodies (3.8%, 95% confidence interval: 1.8%-6.5%). CONCLUSION(S): In women who present with 46,XX spontaneous premature ovarian failure as their primary concern there is a clear association between serum adrenal cortex autoantibodies and the presence of histologically confirmed autoimmune oophoritis.

Characteristics of a monoclonal antibody to the thyrotropin receptor that acts as a powerful thyroid-stimulating autoantibody antagonist.

Analysis of nine mouse monoclonal antibodies (mAbs) to the thyrotropin receptor (TSHR) with TSH antagonist activity showed that only one of the mAbs (RSR B2) was an effective antagonist of the human thyroid stimulating autoantibody M22. Crystals of B2 Fab were analyzed by x-ray diffraction and a crystal structure at 3.3 A resolution was obtained. The surface charge and topography of the B2 antigen binding site were markedly different from those of the thyroid-stimulating mAb M22 and these differences might contribute to the different properties of the two mAbs. B2 (but not other mouse TSHR-specific mAbs) was also an effective antagonist of thyroid stimulating autoantibody activity in 14 of 14 different sera from patients with Graves' disease. 125I-labeled B2 bound to the TSHR with high affinity (2 x 10(10) L/mol) and patient serum TSHR autoantibodies inhibited labeled B2 binding to the receptor in a similar way to inhibition of labeled TSH binding (r = 0.75; n = 20). Furthermore, labeled B2 binding was inhibited by patient serum TSHR autoantibodies with TSH antagonist activity and also by mouse and human thyroid stimulating mAbs. Overall, mAb B2 is a powerful antagonist of thyroid stimulating autoantibodies (and TSH) thus resembling closely patient serum TSH antagonist TSHR autoantibodies. Furthermore, B2 might have potentially important in vivo applications when tissues containing the TSHR (including those in the orbit) need to be made unresponsive to stimulating autoantibodies.

Isolation and characterisation of a human monoclonal autoantibody to the islet cell autoantigen IA-2.

A hybridoma secreting a human monoclonal autoantibody to the islet cell autoantigen IA-2 was prepared from peripheral lymphocytes of a patient with type 1 diabetes and Graves' disease using EBV infection followed by fusion with a mouse/human hybrid cell line. The monoclonal antibody (M13) is an IgG1/kappa and in an immunofluorescence test M13 at 1 microg/mL showed islet cell antibody reactivity equivalent to 40 JDF units. M13 IgG bound (35)S-labelled IA-2 (26% at 100 microg/mL) and (125)I-labelled IA-2 (34% at 100 microg/mL) in an immunoprecipitation assay and reacted well with IA-2 in western blotting analysis. Amino acids 777-808 in the PTP domain of IA-2 were found to be important for M13 binding in an analysis using modified (35)S-labelled IA-2 proteins. M13 V region genes were from VH1-3, D3-22, JH4b, VKI DPK8/Vd+ and JK3 genes and showed a high replacement/silent mutation ratio for both the heavy (11.0) and the light (6.0) chain genes. Mouse monoclonal antibodies (mMAbs) reactive with at least three different epitopes within IA-2 aa 604-686 corresponding to the juxtamembrane domain were also obtained. F(ab')(2) or Fab from the mMAbs inhibited serum IA-2 autoantibody binding to IA-2 in 20/22 diabetic sera whereas M13 F(ab')(2) caused inhibition in only 6/22 sera. M13 is representative of some patient serum IA-2 autoantibodies and as such provides a useful tool to study autoimmune responses to IA-2.

Mechanism of inhibition of cytochrome P450 C21 enzyme activity by autoantibodies from patients with Addison's disease.

OBJECTIVE: To study possible mechanisms for the inhibition of cytochrome P450 C21 (steroid 21-hydroxylase) enzyme activity by P450 C21 autoantibodies (Abs) in vitro. DESIGN: Two possible mechanisms for the inhibition of P450 C21 enzyme activity by P450 C21 Abs were studied: (a) conformational changes in the P450 C21 molecule induced by Ab binding and (b) the effects of Ab binding to P450 C21 on the electron transfer from the nicotinamide adenine dinucleotide phosphate reduced (NADPH) cytochrome P450 reductase (CPR) to P450 C21. METHODS: The effect of P450 C21 Ab binding on the conformation of recombinant P450 C21 in yeast microsomes was studied using an analysis of the dithionite-reduced CO difference spectra. The effect of P450 C21 Abs on electron transfer was assessed by analysis of reduction of P450 C21 in the microsomes in the presence of CO after addition of NADPH. RESULTS: Our studies confirmed the inhibiting effect of P450 C21 Abs on P450 C21 enzyme activity. Binding of the Abs did not induce significant change in the P450 C21 peak at 450nm (native form) and did not produce a detectable peak at 420 nm (denatured form) in the dithionite-reduced CO difference spectra. This indicated that conformation of P450 C21 around the heme was not altered compared with the native structure. However, incubation of the P450 C21 in yeast microsomes with P450 C21 Ab inhibited the fast phase electron transfer from the CPR to P450 C21. CONCLUSIONS: Our observations suggested that the mechanism by which P450 C21 Abs inhibit P450 C21 enzyme activity most likely involves inhibition of the interaction between the CPR and P450 C21.

Assessment of adrenocortical function and autoantibodies in a baby born to a mother with autoimmune polyglandular syndrome Type 2.

We describe the case of a baby born to a mother with Addison's disease in the context of Autoimmune Polyendocrine Syndrome Type 2. Adrenal cortex autoantibodies and steroid 21-hydroxylase autoantibodies were detectable in the sera of both mother and baby, suggesting the transplacental passage of these autoantibodies. Adrenal autoantibodies were present in the baby's serum at delivery, at 3, 6 and till 34 months of age but no signs of clinical or subclinical adrenal insufficiency were found in the baby during the observation period. These data suggest that the presence of adrenal autoantibodies in serum alone is not a sufficient cause for the development of autoimmune adrenalitis.

Autoantibodies to steroidogenic enzymes in patients with premature ovarian failure with and without Addison's disease.

DESIGN: Adrenal cortex autoantibodies (ACA), steroid-producing cell autoantibodies (StCA) and autoantibodies (Abs) to steroidogenic enzymes in three groups of patients with premature ovarian failure (POF), 15 with autoimmune Addison's disease (AD), 26 with non-adrenal autoimmune diseases and 31 with isolated POF, have been assessed. METHODS: ACA and StCA were measured using an immunofluorescence technique. Abs to 21-hydroxylase (21-OH), to 17alpha-hydroxylase (17alpha-OH) and to cytochrome P450 side-chain cleavage (P450scc) were measured using an immunoprecipitation assay. RESULTS: Seventy-three percent of patients with POF and AD were positive for StCA, 93% for 17alpha-OH and/or P450scc Abs, 93% for ACA and 100% for 21-OH Abs. Among patients with POF and non-adrenal autoimmune diseases, 8% were positive for StCA, 12% for 17alpha-OH and/or P450scc Abs, and 8% and 12% for ACA and 21-OH Abs respectively. StCA, 17alpha-OH and/or P450scc Abs were all found in 10% of patients with isolated POF, and 13% had ACA and 21-OH Abs. All StCA-, 17alpha-OH- and/or P450scc Abs-positive patients were also positive for ACA and 21-OH Abs. Two patients with isolated POF who were ACA and 21-OH Ab positive developed AD 3 and 5 Years after the onset of POF. CONCLUSION: This study has shown that, when POF is associated with AD, StCA, 17alpha-OH and/or P450scc Abs are present in the majority of patients, while in the other two groups these Abs are detectable in a much lower proportion of patients. Measurement of ACA/21-OH Abs in some patients with POF may be important in identifying patients at risk of developing overt AD.

Isolation and characterization of human monoclonal autoantibodies to glutamic acid decarboxylase.

Production of human monoclonal autoantibodies to glutamic acid decarboxylase M(r) 65,000 (GAD65), characterization of their isotype, binding affinity, V region sequences and competition with autoantibodies in patients' sera is described. Lymphocytes from a patient with Addison's disease who had GAD65 autoantibodies without diabetes were immortalised and fused to a mouse/human hybridoma. In addition, mouse monoclonal antibodies to GAD65 were produced using standard techniques. F(ab')2S from our monoclonals and the GAD6 mouse monoclonal were used in competition with intact monoclonals and sera from diabetic patients for binding to 125I-labelled GAD65 (amino acids 46-586). Reactivities of the human monoclonals with GAD 65,000/67,000 M(r) chimeras were also studied. Variable region genes of human monoclonals were sequenced and analysed. The human monoclonals (n = 3) had affinity constants for GAD65 of 2.2 x 10(9), 5.8 x 10(9), 1.3 x 10(10) mol/l(-1); affinities of the mouse monoclonals (n = 5) ranged from 1.1 x 10(8) to 5.4 x 10(10) mol/l(-1). The binding of each of the human monoclonals was inhibited by GAD6 F(ab')2 and the binding of GAD6 antibody was inhibited by the human monoclonal F(ab')2S suggesting that the epitopes for these antibodies were overlapping. Studies with GAD65/GAD67 chimeras indicated that the human monoclonals reacted with C-terminal epitopes. The human monoclonals, GAD6 and 3/5 mouse monoclonals inhibited serum autoantibody binding to 125I-labelled GAD65. Overall, the human monoclonals were of high affinity, reacted with C-terminal epitopes and showed evidence of antigen driven maturation; they represented only a proportion of the repertoire of autoantibodies to GAD65 in the donor's serum and in the sera of patients with type-1 diabetes.