Serum Visfatin does not seem to be a Useful Marker to Guide Glucocorticoid Substitution in Adrenal Insufficiency.

Primary adrenal insufficiency (Addison's disease, AD) requires lifelong steroid substitution. Excess exogenous glucocorticoids promote abdominal obesity, insulin-glucose imbalance, and hypertension. Reliable markers of the adequate glucocorticoid replacement are lacking. Visfatin is a pro-inflammatory adipokine, with enzymatic activity of nicotinamide phosphoribosyltransferase. It enhances leukocyte function and synthesis of tumour necrosis factor α (TNFα) and interleukin-6 (IL-6). Serum visfatin is elevated in autoimmunity, but also in obesity, insulin resistance, and metabolic syndrome. This study was aimed to investigate whether serum visfatin could guide the glucocorticoid substitution in AD. Biochemical analyses were performed in 96 patients with AD (mean age 43.3±14.9 years) and 91 controls (43.5±12.5 years). Visfatin level was significantly elevated in patients with AD compared to controls (p<0.0001). Higher circulating IL-6 was also detected among subjects with AD (p=0.006). In AD, visfatin level was positively correlated with IL-6 (p=0.014), TNFα (p=0.001), body mass (p=0.015), fasting insulin (p=0.001) and HOMA-IR (p=0.001). No relationship was noticed with daily hydrocortisone (p=0.096) and urinary free cortisol excretion (p=0.499). Only the correlations with IL-6 and fasting insulin survived multiple regression analysis (p=0.049 and p=0.005, respectively). Additionally, positive correlation between visfatin and autoantibodies to 21-hydroxylase was noted (p=0.005). In the control group serum visfatin was correlated with IL-6 (p=0.009) and TNFα (p=0.0002). The current study reveals elevated serum visfatin in autoimmune AD. Visfatin does not seem a useful marker of the glucocorticoid replacement, although it correlates with fasting insulin and pro-inflammatory molecules. Further functional analyses are warranted to elucidate the role of visfatin in autoimmunity.

MECHANISMS IN ENDOCRINOLOGY: Update on pathogenesis of primary adrenal insufficiency: beyond steroid enzyme deficiency and autoimmune adrenal destruction.

Primary adrenal insufficiency (PAI) is potentially life threatening, but rare. In children, genetic defects prevail whereas adults suffer more often from acquired forms of PAI. The spectrum of genetic defects has increased in recent years with the use of next-generation sequencing methods and now has reached far beyond genetic defects in all known enzymes of adrenal steroidogenesis. Cofactor disorders such as P450 oxidoreductase (POR) deficiency manifesting as a complex form of congenital adrenal hyperplasia with a broad clinical phenotype have come to the fore. In patients with isolated familial glucocorticoid deficiency (FGD), in which no mutations in the genes for the ACTH receptor (MC2R) or its accessory protein MRAP have been found, non-classic steroidogenic acute regulatory protein (StAR) and CYP11A1 mutations have been described; and more recently novel mutations in genes such as nicotinamide nucleotide transhydrogenase (NNT) and thioredoxin reductase 2 (TRXR2) involved in the maintenance of the mitochondrial redox potential and generation of NADPH important for steroidogenesis and ROS detoxication have been discovered. In addition, whole exome sequencing approach also solved the genetics of some syndromic forms of PAI including IMAGe syndrome (CDKN1C), Irish traveler syndrome (MCM4), MIRAGE syndrome (SAMD9); and most recently a syndrome combining FGD with steroid-resistant nephrotic syndrome and ichthyosis caused by mutations in the gene for sphingosine-1-phosphate lyase 1 (SGPL1). This review intends do give an update on novel genetic forms of PAI and their suggested mechanism of disease. It also advocates for advanced genetic work-up of PAI (especially in children) to reach a specific diagnosis for better counseling and treatment.

Determination of 21-hydroxylase autoantibodies: inter-laboratory concordance in the Euradrenal International Serum Exchange Program.

BACKGROUND: 21-Hydroxylase autoantibodies (21OHAb) are markers of an adrenal autoimmune process that identifies individuals with autoimmune Addison's disease (AAD). Quality and inter-laboratory agreement of various 21OHAb tests are incompletely known. The objective of the study was to determine inter-laboratory concordance for 21OHAb determinations. METHODS: Sixty-nine sera from 51 patients with AAD and 51 sera from 51 healthy subjects were blindly coded by a randomization center and distributed to 14 laboratories that determined 21OHAb, either by an "in-house" assay (n=9) using in vitro-translated (35)S-21OH or luciferase-labeled 21OH or a commercial kit with (125)I-21OH (n=5). Main outcome measures were diagnostic accuracy of each participating laboratory and inter-laboratory agreement of 21OHAb assays. RESULTS: Intra-assay coefficient of variation ranged from 2.6% to 5.3% for laboratories using the commercial kit and from 5.1% to 23% for laboratories using "in-house" assays. Diagnostic accuracy, expressed as area under ROC curve (AUC), varied from 0.625 to 0.947 with the commercial kit and from 0.562 to 0.978 with "in-house" methods. Cohen's κ of inter-rater agreement was 0.603 among all 14 laboratories, 0.691 among "in-house" laboratories, and 0.502 among commercial kit users. Optimized cutoff levels, calculated on the basis of AUCs, increased the diagnostic accuracy of every laboratory (AUC >0.9 for 11/14 laboratories) and increased the Cohen's κ of inter-rater agreement. Discrepancies in quantitation of 21OHAb levels among different laboratories increased with increasing autoantibody levels. CONCLUSIONS: The quality of 21OHAb analytical procedures is mainly influenced by selection of cutoff value and correct handling of assay materials. A standardization program is needed to identify common standard sera and common measuring units.

Gonadal function in males with autoimmune Addison's disease and autoantibodies to steroidogenic enzymes.

Steroidogenic enzyme autoantibodies (SEAbs) are frequently present and are markers of autoimmune premature ovarian failure (POF) in females with autoimmune Addison's disease (AAD). The prevalence and significance of SEAbs in males with AAD have not yet been defined. We studied the prevalence of SEAbs in a large cohort of males with AAD and assessed the relationship between SEAbs positivity and testicular function. A total of 154 males with AAD (mean age 34 years) were studied. SEAbs included autoantibodies to steroid-producing cells (StCA), detected by immunofluorescence, and steroid 17α-hydroxylase (17α-OHAbs) and side chain cleavage enzyme (SCCAbs) measured by immunoprecipitation assays. Gonadal function was evaluated by measuring follicle-stimulating hormone (FSH), luteinizing hormone (LH), total testosterone (TT), sex hormone-binding globulin (SHGB), anti-müllerian hormone (AMH) and inhibin-B (I-B). Twenty-six males, 10 SEAbs((+)) and 16 SEAbs((-)), were followed-up for a mean period of 7·6 years to assess the behaviour of SEAbs and testicular function. SEAbs were found in 24·7% of males with AAD, with the highest frequency in patients with autoimmune polyendocrine syndrome type 1 (APS-1). The levels of reproductive hormones in 30 SEAbs((+)) males were in the normal range according to age and were not significantly different compared to 55 SEAbs((-)) males (P > 0·05). During follow-up, both SEAbs((+)) and SEAbs((-)) patients maintained normal testicular function. SEAbs were found with high frequency in males with AAD; however, they were not associated with testicular failure. This study suggests that the diagnostic value of SEAbs in males with AAD differs compared to females, and this may be related to the immunoprivileged status of the testis.

Elevación crónica de creatincinasa / Chronic creatinine elevation

Las miopatías son entidades en las que se produce afectación musculo esquelética con elevación de creatincinasa en suero. La Enfermedad de Addison y la Hipertermia Maligna constituyen causas poco comunes de miopatía. La Enfermedad de Addison corresponde a una insuficiencia suprarrenal primaria producida por un déficit de glucocorticoides, mineral corticoides y andrógenos por destrucción de la corteza suprarrenal, cuyos síntomas son inespecíficos y el tratamiento es con hidrocortisona. La Hipertermia Maligna se produce por una alteración genética en la que los anestésicos inhalados y los relajantes musculares desencadenan una hipertermia progresiva, con rigidez muscular, taquicardia, hipotensión, rabdomiolisis, y coagulación intravascular diseminada (AU)

Myopathy is a disease that affects the musculoskeletal system with elevated serum creatinine. Addison’s Disease and Malignant Hyperthermia, are rare causes of myopathy. Addison’s disease, also known as primary adrenal insufficiency, occurs when the adrenal gland does not produce enough glucocorticoids, mineralocorticoids and androgens because of the destruction of the adrenal cortex. Symptoms are non-specific and it is treated with hydrocortisone. Malignant Hyperthermia is a genetic disorder, in which inhaled anaesthetics and muscle relaxants, trigger progressive hyperthermia with muscle rigidity, tachycardia, hypotension, rhabdomyolysis, and disseminated intravascular coagulation (AU)

[Prevalence of anti-thyroid peroxidase and anti-adrenal 21-hidroxylase in type 1 diabetes patients]. / Prevalência do anti-TPO e anti-21-hidroxilase no paciente diabético tipo 1.

UNLABELLED: There is still no consensus about the best strategy to screen Addison's disease (AD) in type 1 diabetes mellitus (T1DM) patients. OBJECTIVE: The aim of this study was to determine the frequency of anti-21-hydroxilase (anti-21OH) in a multiethnic T1DM population and investigate if its presence is associated with any adrenal dysfunction or thyroid autoimmunity. METHODS: Forty individuals underwent an interview and blood was drawn for anti-thyroperoxidase (anti-TPO), anti-21OH, TSH, free T4 and cortisol measurement. RESULTS: Anti-21OH was found in 7.5% (n = 3), none with adrenal dysfunction. This antibody was not exclusively seen in patients with anti-TPO (+). Anti-TPO was positive in 25% and associated with higher TSH levels (p = 0.034) and older age (p = 0.009). CONCLUSIONS: Although the frequency of anti-TPO in this sample was similar to previous studies, a higher prevalence of anti-21-OH was found. However, no coexisting adrenal dysfunction was detected, which does not support universal screening for AD in this group.

Prevalência do anti-TPO e anti-21-hidroxilase no paciente diabético tipo 1 / Prevalence of anti-thyroid peroxidase and anti-adrenal 21-hidroxylase in type 1 diabetes patients

Ainda não está definida a estratégia ideal para rastrear a doença de Addison em pacientes com diabetes melito tipo 1 (DMT1). Objetivo: O objetivo deste estudo foi determinar a prevalência do anticorpo anti-21-hidroxilase (AC anti-21OH) em pacientes DMT1 de etnia diversificada e investigar sua associação à disfunção adrenal e autoimunidade tireoidiana. Métodos: Quarenta indivíduos foram avaliados, submetidos à entrevista e à dosagem de AC antitireoperoxidase (anti-TPO), anti-21OH, TSH, T4 livre e cortisol. AC anti-21OH foi encontrado em 7,5% (n = 3)dos casos, sem disfunção adrenal associada. Resultados: Positividade para anti-21OH não ocorreu exclusivamente em pacientes com anti-TPO (+). Este foi detectado em 25% dos casos e associado a níveis de TSH mais elevados (p = 0,034) e à idade mais avançada (p = 0,009). Conclusões: Embora nossa frequência de anti-TPO (+) seja similar à da literatura, a presença de anti-21OH (+) foi superior. Entretanto, esses AC não foram associados à disfunção hormonal, o que parece não justificar o rastreamento universal da doença de Addison.

There is still no consensus about the best strategy to screen Addison’s disease (AD) in type 1 diabetes mellitus (T1DM) patients. Objective: The aim of this study was to determine the frequency of anti-21-hydroxilase (anti-21OH) in a multiethnic T1DM population and investigate if its presence is associated with any adrenal dysfunction or thyroid autoimmunity. Methods: Forty individuals underwent an interview and blood was drawn for anti- thyroperoxidase (anti-TPO), anti-21OH, TSH, free T4 and cortisol measurement. Results: Anti-21OH was found in 7.5% (n = 3), none with adrenal dysfunction. This antibody was not exclusively seen in patients with anti-TPO (+). Anti-TPO was positive in 25% and associated with higher TSH levels (p = 0.034) and older age (p = 0.009). Conclusions:Although the frequency of anti-TPO in this sample was similar to previous studies, a higher prevalence of anti-21-OH was found. However, no coexisting adrenal dysfunction was detected, which does not support universal screening for AD in this group.

[Addison's disease as a rare cause of chronically elevated liver enzymes]. / Morbus Addison als seltene Ursache für chronisch erhöhte Transaminasen.

Common causes of chronically elevated serum liver enzymes include fatty liver disease, chronic viral hepatitis, autoimmune hepatitis, or hereditary metabolic disorders. Adrenocortical insufficiency can also cause elevated liver enzymes. Since 1990 only 11 cases have been reported. We here report a 52-year-old man with elevated liver enzymes (1.5 x upper limit of normal) over the past 10 years. Furthermore, hyponatremia and hyperkalemia were noted. He complained of fatigue and low blood pressure over the past few years. At physical examination a dark complexion was noted. After ruling out chronic viral hepatitis, autoimmune disease, metabolic or hereditary disorders, rare causes of elevated liver enzymes were considered. The endocrinological work-up revealed Addison's disease as cause of serum electrolyte disturbance and elevated liver enzymes. The patient was successfully treated with hydrocortisol and fludrocortisol. After one week, liver enzymes, serum electrolytes and arterial blood pressure had normalized. In conclusion, for patients with constantly elevated liver enzymes also rare, extrahepatic diseases have to be considered. Addison's disease is a rare but fully reversible cause for elevated liver enzymes.

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.

Autoantibodies against glutamic acid decarboxylase and 21-hydroxylase in Brazilian patients with type 1 diabetes or autoimmune thyroid diseases.

Autoimmune thyroid diseases (ATD) are often associated with Type 1 diabetes mellitus (T1DM) and Addison's disease (AD), characterizing the autoimmune polyendocrine syndrome. We evaluated the frequency of autoantibodies against glutamic acid decarboxylase isoform 65 (GAD65Ab) and 21-hydroxylase (21OHAb) in the sera of 65 [58 females (F)/7 males (M), 17-70 yr] patients with Graves' disease (GD) and 47 (45 F/2 M, 12-77 yr) with Hashimoto's thyroiditis (HT), none of whom had either diabetes or AD. The sera of 30 recently diagnosed T1DM patients (16 M/14 F, 1-39 yr) and of 97 (54 F/43 M, 7-69 yr) healthy controls were also examined. GAD65Ab were detected in the sera of 18 (60%) T1DM, 8 (12%) GD and in none of the HT patients or the controls (p = 0.03 for GD vs HT, p = 0.002 for GD vs controls, and p < 0.001 for GD vs T1DM). 21OHAb were detected in the sera of 2 (3%) GD, 1 (2%) HT and in none of the T1DM patients or the controls. GAD65Ab levels were significantly lower in GD than in T1DM patients (median: -0.06 vs 0.28, p < 0.001). Six of the 8 GD GAD65Ab-positive patients submitted to an intravenous glucose tolerance test showed no diminished first phase insulin secretion. All 21OHAb positive patients had normal basal cortisol and adrenocorticotropin (ACTH), normal cortisol response after ACTH stimulation, but high plasma renin activity. In conclusion, despite the genetic diversity of the Brazilian population, the frequency of GAD65Ab and 21OHAb in our patients is similar to that observed in other countries. GAD65Ab were more prevalent in GD than in HT patients, suggesting a difference in the immune response between these disorders. Long-term follow-up is necessary to determine the clinical relevance of these autoantibodies in the Brazilian population.

3beta-hydroxysteroid dehydrogenase autoantibodies are rare in premature ovarian failure.

Premature ovarian failure (POF) is a disorder of heterogeneous etiology, and autoimmunity has been suspected as one cause of POF. The steroidogenic enzyme, 3beta-hydroxysteroid dehydrogenase (3betaHSD), has been characterized as a potential autoantigen in POF as well as in insulin-dependent diabetes mellitus (type 1 diabetes). Here we studied the presence of steroid cell antibodies (SCA), autoantibodies to 3betaHSD and to two other known autoantigens in ovarian failure, steroidogenic enzymes 17alpha-hydroxylase (P450c17), and side-chain cleavage enzyme (P450scc) in POF patients and patient groups with autoimmune polyendocrinopathy syndromes type 1 and 2 (APS1 and -2), isolated Addison's disease, type 1 diabetes, and healthy controls. The SCA were found in 2 of 48 POF, 11 of 15 APS1, and 1 of 9 APS2, and autoantibodies to in vitro translated 3betaHSD protein were detected in 1 POF serum associated with Addison's disease and 3 APS1 sera. All 3betaHSD precipitating sera were also positive for SCA. However, no SCA or 3betaHSD autoantibodies were found in 38 Addison's disease, 28 type 1 diabetes, and 71 healthy control sera. In analysis of autoantibodies to P450c17 and P450scc, antibodies to these enzymes were not found in POF sera, but were found in 10 and 12 APS1 patient sera, respectively, and 1 APS2 patient serum contained anti-P450c17 antibodies. Our results show that autoantibodies to 3betaHSD in POF patients are rare and are also found in patients with APS1.

A conformation-dependent epitope in Addison's disease and other endocrinological autoimmune diseases maps to a carboxyl-terminal functional domain of human steroid 21-hydroxylase.

Idiopathic Addison's disease develops as a consequence of autoimmune destruction of steroid-producing cells in the adrenal gland. A major autoantigen is 21-hydroxylase (21OH; P450c21), which is involved in the biosynthesis of cortisol and aldosterone in the adrenal cortex. We selected a number of functionally important 21OH amino acid substitutions, found in patients with congenital adrenal hyperplasia, to study their effects on the binding of 21OH autoantibodies (21OHAb) to 21OH. The ability of 21OHAb to bind in vitro transcribed and translated wild-type 21OH and five different 21OH mutant proteins was quantified by liquid-phase assays. Sera from 21OHAb-positive patients with idiopathic Addison's disease (n = 24), Graves' disease (n = 3), and insulin-dependent diabetes mellitus (n = 1) were used. While the P105L, delE196, and G291S mutations had no effect on autoantibody binding, the P453S mutation had a considerable effect, and the R483P mutation almost completely abolished binding. Synthetic peptides corresponding to linear epitopes defined by amino acids 447-461 and 477-491 were unable to compete with wild-type 21OH for binding to autoantibodies. Direct 21OH DNA sequencing could not reveal any specific genetic variation in alleles found in 21OHAb-positive patients. We conclude that the region involving R483 plays a key role in the formation of a three-dimensional epitope in a functionally important C-terminal domain of the enzyme.

A study of the epitopes on steroid 21-hydroxylase recognized by autoantibodies in patients with or without Addison's disease.

Steroid 21-hydroxylase (21-OH) autoantibodies are found in patients with autoimmune Addison's disease (AAD), either isolated or associated with autoimmune polyglandular syndrome (APS) type I and II and in adrenal-cortex autoantibody (ACA)-positive patients without AAD. In order to assess any differences in the 21-OH autoantibodies in these different patient groups, we have studied their reactivity with different epitopes on 21-OH using full length and modified 35S-labelled 21-OH proteins produced in an in vitro transcription/translation system. There were no major differences in the pattern of autoantibody reactivity with the different modified 21-OH proteins in patients with isolated AAD or with APS types I and II, and in 21-OH autoantibody-positive patients with clinical AAD, subclinical AAD and those maintaining a normal adrenal function. Our studies also indicate that the main epitopes for 21-OH autoantibodies in patients with different forms of autoimmune adrenal disease are located in the C-terminal end and in a central region of 21-OH.

Subclinical Addison's disease: a cause of persistent abnormalities in transaminase values.

A common reason for referring patients to hepatologists is persistently abnormal serum transaminase levels with vague constitutional symptoms. In the United Kingdom, these abnormalities are most often caused by a fatty liver either related to obesity or alcohol abuse; they are less commonly caused by chronic liver disease, particularly chronic viral hepatitis, autoimmune hepatitis, or chronic biliary disease. Endocrine disease is rarely a cause of these abnormalities, although hypothyroidism and hyperthyroidism are well-recognized causes. Addison's disease has been only reported once in the literature by R. G. Olsson as a cause of increased transaminase levels associated with constitutional symptoms; it is not mentioned in textbooks on hepatology. Three patients with Addison's disease are reported here, all of whom had increased serum transaminase levels for more than 6 months before the recognition of the hypoadrenalism with resolution to normal after steroid replacement. Hepatologists should consider subclinical Addison's disease as a cause of persistently increased transaminase levels with constitutional symptoms in the absence of evidence for fatty liver as well as viral and autoimmune markers.

Autoantibody epitope mapping of the 21-hydroxylase antigen in autoimmune Addison's disease.

Patients with idiopathic Addison's disease are characterized by cytoplasmic adrenal autoantibodies, detectable by indirect immunofluorescence of cryocut sections of human adrenal cortex. Recently, autoantibodies that bind a 55-kilodalton protein in the microsomal fraction of adrenal gland extracts identified to be the cytochrome P450 enzyme 21-hydroxylase have been found in Addisonian patient sera. We confirm the finding and report here the autoantigenic epitopes involved in the autoantibody reactivity using recombinant DNA technology. Six cDNA fragments spanning different regions of the 21-hydroxylase gene were expressed as fusion proteins with glutathione S-transferase in Escherichia coli. Immunoblot analyses were used to evaluate the reactivity of the recombinant proteins with patients' sera to determine the autoepitopes involved. We found that a conserved region (amino acids 164-356) reacted with 25 of 30 adrenal autoantibody-positive sera tested. One serum sample reacted only with the amino portion of the 21-hydroxylase (amino acids 1-162). In addition, 4 other enzymes important to steroid hormone biosynthesis, 11 beta-hydroxylase, 17 alpha-hydroxylase, side-chain cleavage enzyme P450, and 3 beta-hydroxysteroid dehydrogenase, were expressed in E. coli, but none of them gave positive autoantibody reactions by Western blot assays, even using sera from 5 patients with type I autoimmune polyglandular syndrome. The availability of recombinant antigens has permitted structural analysis of the autoepitopes involved in the autoimmune response to 21-hydroxylase in Addison's disease. Our findings should lead to the development of a simple and specific tool for immunodiagnosis of the disease.

Autoantibodies to cytochrome P450 enzymes P450scc, P450c17, and P450c21 in autoimmune polyglandular disease types I and II and in isolated Addison's disease.

Patients with idiopathic Addison's disease have autoantibodies reacting with adrenal cortex. If Addison's disease is associated with other endocrine immune diseases like autoimmune polyglandular diseases (APD) type I and type II, antibodies may recognize all steroid-producing cells. We showed previously that one antigen recognized by APD-I sera is the cytochrome P450c17 hydroxylase. We have now looked for antibodies to P450c17 and to two other key enzymes in the steroid biosynthetic pathway, the P450scc and P450c21, in a series of patients with isolated Addison's disease (8 patients) or with APD-I or APD-II (50 and 9 patients, respectively). The result of antienzyme antibodies were further correlated with the immunofluorescence pattern against adrenal gland, testis, ovary, and placenta, and with the clinical findings presented. In APD-I patients with Addison's disease and in APD-II patients, antibodies to at least one of the P450 enzymes were frequently found (positive findings in 81% and 78%, respectively). Such antibodies were less frequent in APD-I patients without Addison's disease (21%) and in the isolated Addison cases (25%). In APD-I, antibodies recognized as frequently P450c17 and P450scc, specific for all steroid-producing cells as the adrenal specific enzyme P450c21. In contrast, patients with APD-II or with the isolated Addison's disease reacted almost exclusively with P450c21. Immunofluorescence studies showed good correlation with the known fact that the zona glomerulosa of the adrenal cortex is devoid of the P450c17, that the Leydig cells of the testis and the theca interna cells of the ovary express P450c17 and P450scc, and that the placental trophoblasts express only P450scc. The presence of antibodies to P450scc or to at least one of the tested P450 enzymes correlated significantly to gonadal failure in the females but not in the males.

Two different cytochrome P450 enzymes are the adrenal antigens in autoimmune polyendocrine syndrome type I and Addison's disease.

Autoimmune polyendocrine syndrome type I (APS I) and idiopathic Addison's disease are both disorders with adrenal insufficiency but with differences in genetic background, clinical presentation, and extent of extraadrenal manifestations. In this study the major adrenal autoantigen identified with sera from patients with APS I was characterized by analyses using indirect immunofluorescence, Western blots of adrenal subcellular fractions and of recombinant proteins, immunoprecipitations of [35S]methionine-labeled lysates of a human steroid-producing cell line, and studies of enzymatic activity. Sera from patients with APS I, identifying cells in adrenal glands and testes involved in steroid synthesis, reacted in Western blots with a 53-kD antigen, which comigrated with the cytochrome P450 cholesterol side chain cleavage enzyme (SCC). The sera also immunoprecipitated this protein from lysates of radiolabeled adrenal cells. The enzymatic activity of SCC was inhibited by the APS I sera but not by control sera. Sera from patients with idiopathic Addison's disease did not react with the SCC. The results show that the autoimmune responses towards adrenal tissue in patients suffering from APS I and Addison's disease are remarkably selective and suggest that a determination of the antigen involved in a patient with autoimmune adrenal insufficiency will have diagnostic as well as prognostic implications.

Steroid 21-hydroxylase is a major autoantigen involved in adult onset autoimmune Addison's disease.

An adrenal-specific protein reacting with autoantibodies in the sera of patients with adult onset Addison's disease has been purified from human adrenal glands. The protein, mol.wt. 55K, has the biochemical characteristics of steroid 21-hydroxylase and reacts on Western blots with rabbit antibodies to recombinant 21-hydroxylase. Absorption of the native human 55K adrenal protein with human adrenal autoantibodies prevented the subsequent reaction of the 55K protein with rabbit antibodies to 21-hydroxylase in Western blot analysis. In addition, human adrenal autoantibodies reacted with recombinant 21-hydroxylase expressed in yeast. These data indicate that the adrenal specific enzyme steroid 21-hydroxylase is a major autoantigen involved in adult onset autoimmune Addison's disease.