Revising the classification criteria for systemic sclerosis.
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Humans↗
Biomedical subjects
M J Fritzler
Publications and source records attributed to M J Fritzler.
Human autoantibodies against early endosome antigen-1 enhance excitatory synaptic transmission.
Early endosome antigen 1 (EEA1), a peripheral membrane protein associated with the cytoplasmic face of early endosomes, controls vesicle fusion during endocytosis, as extensively studied in non-neuronal cells. In neurons, early endosomes are involved in recycling of synaptic vesicles and neurotransmitter receptors. Since certain patients bearing autoantibodies that target EEA1 develop neurological disease, we studied the subcellular distribution of EEA1 in neurons and the effect on neurotransmission of purified immunoglobulins from the serum of a patient bearing EEA1 autoantibodies. EEA1 was localized in the soma and in the postsynaptic nerve terminals. Electrophysiological recordings in hippocampal slices including purified EEA1 antibodies in the patch pipette solution, revealed a run-up of AMPA, N-methyl-D-aspartate and kainate receptor-mediated excitatory post-synaptic currents recorded from CA3 pyramidal neurons, which was absent in the recordings obtained in the presence of control human immunoglobulin G. Inclusion of human EEA1 antibodies had no effect on inhibitory post-synaptic responses. Recordings in the presence of a dominant-negative C-terminal EEA1 deletion mutant produced a similar effect as observed with human anti-EEA1 antibodies. This specific effect on the excitatory synaptic transmission may be due to the impairment of internalization of specific glutamate receptors and their subsequent accumulation in the synapse. These results may account for the neurological deficits observed in some patients developing EEA1 autoantibodies.
Animals↗
Human autoantibodies to diacyl-phosphatidylethanolamine recognize a specific set of discrete cytoplasmic domains.
The aim of this study was to characterize a novel human autoantibody-autoantigen system represented as cytoplasmic discrete speckles (CDS) in indirect immunofluorescence (IIF). A distinct CDS IIF pattern represented by 3-20 discrete speckles dispersed throughout the cytoplasm was identified among other cytoplasmic speckled IIF patterns. The cytoplasmic domains labelled by human anti-CDS-1 antibodies did not co-localize with endosome/lysosome markers EEA1 and LAMP-2, but showed partial co-localization with glycine-tryptophan bodies (GWB). CDS-1 sera did not react with several cellular extracts in immunoblotting and did not immunoprecipitate recombinant GW182 or EEA1 proteins. The typical CDS-1 IIF labelling pattern was abolished after delipidation of HEp-2 cells. Moreover, CDS-1 sera reacted strongly with a lipid component co-migrating with phosphatidylethanolamine (PE) in high performance thin-layer chromatography (HPTLC)-immunostaining of HEp-2 cell total lipid extracts. The CDS-1 major molecular targets were established by electrospray ionization-mass spectrometry (ESI-MS), HPTLC-immunostaining and chemiluminescent enzyme-linked immunosorbent assay as diacyl-PE species, containing preferentially a cis-C18 : 1 fatty acid chain at C-2 of the glycerol moiety, namely 1,2-cis-C18 : 1-PE and 1-C16 : 0-2-cis-C18 : 1-PE. The clinical association of CDS-1 sera included a variety of systemic and organ-specific autoimmune diseases but they were also observed in patients with no evidence of autoimmune disease.
Adult↗
Anti-p97/VCP antibodies: an autoantibody marker for a subset of primary biliary cirrhosis patients with milder disease?
We previously reported that 12.5% of primary biliary cirrhosis (PBC) sera reacted with a 95 kDa cytosol protein (p95c) that was subsequently identified as a p97/valosin-containing protein (VCP). The clinical features and course of the six anti-p97/VCP-positive PBC patients with Scheuer's stage 1 and 2 liver biopsies were monitored for an average of 15 years. This group was compared with 50 PBC patients that did not have detectable anti-VCP. Autoantibodies to a full-length recombinant p97/VCP were assayed by immunoprecipitation. All six PBC patients with anti-VCP had antibodies to the mitochondrial pyruvate dehydrogenase complex-E2 antigen as measured by an addressable laser bead immunoassay. The first was a male with no evidence of liver failure that died of cerebral infarction at the age of 85. The second was a 73-year-old female with Hashimoto's thyroiditis who has remained clinically stable without ursodeoxycolic acid (UDCA) treatment. Although the third had no HCV antibodies, he developed hepatocellular carcinoma at the age of 76 and died of renal failure at 78. The fourth was a 50-year-old female who remained clinically stable during follow-up and the fifth with Hashimoto's thyroiditis and stable liver function following UCDA treatment. The sixth was a male patient presenting a mild clinical course. The clinical course of these patients was in contrast to the 50 comparison group PBC patients who did not have anti-p97/VCP. As the six PBC patients with anti-p97/VCP antibodies had slowly progressive liver disease and no mortality related to autoimmune liver disease, our observations suggest that this autoantibody might be an indicator of a favourable prognosis.
Adenosine Triphosphatases↗
Advances and applications of multiplexed diagnostic technologies in autoimmune diseases.
There is a rapid proliferation of new technologies to identify an ever increasing spectrum of autoantibodies in diverse medical conditions that range from organ-specific autoimmune diseases to systemic rheumatic diseases. Although many laboratories have adopted diagnostic platforms, such as enzyme linked immunoassays (ELISAs), to improve turn around times and meet budget constraints, the prevailing evidence is that the rapid adoption of new technologies is not attended by an appropriate balance of assay sensitivity and specificity. Emerging diagnostic technologies include addressable laser bead immunoassays, microarrays in microfluidics platforms and nanobarcode particles. Although these technologies provide advantages of high-throughput, multiplexed autoantibody assays that can be coupled to other disease specific biomarkers (ie, cytokines, single nucleotide polymorphisms) there is a clear need for standardization and internal validation before they are adopted into the clinical diagnostic laboratory.
Animals↗
Major immunoreactive domains of human ribosomal P proteins lie N-terminal to a homologous C-22 sequence: application to a novel ELISA for systemic lupus erythematosus.
The aim of this study was to identify immunoreactive domains on human ribosomal P0, P1 and P2 proteins, other than the C-22 peptide, to develop a novel ELISA using a combination of these proteins and to compare this ELISA with one using the C-22 peptide. Human recombinant P0, P1, P2 and mutant P0 lacking the homologous C-22 peptide (N-P0) were produced in bacteria and tested by ELISA and immunoblotting using sera from 48 patients with systemic lupus erythematosus (SLE), 48 with an unrelated inflammatory disorder (Crohn's disease) and 47 healthy controls. ELISA with P0, P1 and P2, premixed at equimolar concentrations, gave higher OD readings than each protein tested individually. Eighteen SLE sera tested positive by ELISA with premixed P0, P1, P2 but only 3 tested positive with the C-22 peptide. Twenty-two SLE sera reacted positively, as determined by immunoblotting, with 5 different P protein combinations: P1P2, P0P1P2, P1, P0P1, P0 and P1. Only sera reactive with all three P proteins reacted with the C-22 peptide, with absent or minimal reactivity with N-P0. Native antigens yielded sensitivity (6/48, 13%) similar to the C-22 peptide assay. An ELISA with premixed P1 and P2 gave higher OD values than the arithmetic means with P1 or P2. Fifteen SLE patients had antibodies to double stranded (ds)-DNA, of which 6 also had antibodies to P0P1P2 by ELISA but 12 reactive with P0P1P2 did not have discernable ds-DNA antibodies. Ribosomal P autoantibodies react mainly with epitopes N-terminal to a homologous C-22 peptide. An ELISA with premixed P0, P1 and P2 has 5-fold greater sensitivity (38%) for SLE than an assay with the conventional C-22 peptide (7%). The combined sensitivity for SLE for antibodies to P0P1P2 and ds-DNA is 56%, higher than C-22 and ds-DNA, 38%. Only one of the SLE patients had neuropsychiatric lupus.
Amino Acid Sequence↗
Improved serological differentiation between systemic lupus erythematosus and mixed connective tissue disease by use of an SmD3 peptide-based immunoassay.
Autoantibodies to the Sm antigens are specifically found in 5 to 30% of patients with systemic lupus erythematosus (SLE) depending on the detection system and the patient group. Several immunoassays designed for research and diagnostic laboratory use have been developed. The autoantigens employed in these tests include purified native proteins, recombinant polypeptides, and synthetic peptides. In the present study, we compared the clinical accuracy of anti-Sm autoantibody assays from commercial suppliers including different conventional enzyme-linked immunosorbent assay (ELISA) systems based on purified Sm antigens, an addressable laser bead assay and a newly developed anti-Sm peptide assay. Although the clinical sensitivity of all assays under investigation was comparable, relatively poor correlations and significant differences in specificity were found with a patient cohort of 150 patients. The sensitivity and specificity were 10 and 94%, respectively, for the anti-Sm ELISA from Euroimmun, 10 and 90%, respectively, for the QuantaLite Sm (INOVA), 12 and 88%, respectively, for the Sm assay in the Varelisa ReCombi ANA profile (Pharmacia Diagnostics), 10 and 94%, respectively, for the QuantaPlex Sm (INOVA), and 12 and 100%, respectively, for the new SmD3 peptide-based ELISA (Varelisa Sm Antibodies). The majority of positive test results within the control groups were found in patients with mixed connective tissue disease. Based on the results, we conclude that the detection of anti-Sm antibodies strongly depends both on the nature of the antigen and on the detection system. Finally, we conclude that the recently identified SmD peptide containing a symmetrical dimethylarginine at position 112 of D3 represents a promising tool for the detection of a highly specific subpopulation of anti-Sm antibodies.
Antibodies, Antinuclear↗
Autoantigens of the nuclear pore complex.
The nuclear envelope (NE) is one of many intracellular targets of the autoimmune response in patients with autoimmune liver disease, systemic lupus erythematosus, and related conditions. In eukaryotic organisms the NE consists of five interconnected regions: an outer nuclear membrane (ONM) that is continuous with the endoplasmic reticulum, an intermembrane or perinuclear space, an inner nuclear membrane (INM) with a unique set of integral membrane proteins, the underlying nuclear lamina, and the pore domains that are regions where the ONM and INM come together. The pore domains are sites of regulated continuity between the cytoplasm and nucleus that are occupied by supramolecular structures, termed nuclear pore complexes (NPCs). Human autoantibodies identified to date bind to specific components in three of the five NE compartments. Autoantigen targets include the lamins A, B, and C of the nuclear lamina, gp210, p62 complex proteins, Nup153, and Tpr within the NPC, and LBR, MAN1, LAP1, and LAP2 that are integral proteins of the INM. Autoantibodies to these NE targets have been shown to be correlated with various autoimmune diseases such as primary biliary cirrhosis, other autoimmune liver diseases and systemic rheumatic diseases. Now that the proteome of the NE is more clearly defined, other autoantibodies to components in this cell compartment are likely to be defined.
Animals↗
Technical and clinical evaluation of anti-ribosomal P protein immunoassays.
Autoantibodies to the three ribosomal phospho (-P) proteins P0, P1, P2, referred to as Rib-P, are specifically found in 10-40% of patients with systemic lupus erythematosus. The variations in the observed frequency of these autoantibodies is related to a number of factors such as the test system used to detect the antibodies. Several immunoassays that were designed for research and diagnostic laboratory use have been developed. The autoantigens employed in these tests include native proteins, recombinant polypeptides, and synthetic peptides. In this study, we compared the technical and clinical accuracy of anti-Rib-P antibody assays from different commercial suppliers including ELISA systems and a novel addressable laser bead assay (from Euroimmun, MBL, Pharmacia Diagnostics, INOVA). Although the assays from all suppliers used in this study performed well in the technical part of the study, relatively poor correlations and significant differences in the clinical accuracy were found. Based on the results, we conclude that the detection of anti-Rib-P antibodies strongly depends on both the nature of the antigen and the detection system. We recommend that anti-Rib-P assays should be standardized on an international level. The Varelisa Rib-P profile and the addressable laser bead Rib-P assays represent promising tools and platforms for the detection of anti-Rib-P antibodies in the future.
Animals↗
The nuclear pore complex protein Tpr is a common autoantigen in sera that demonstrate nuclear envelope staining by indirect immunofluorescence.
We studied the autoantigen targets of 75 human sera that had antibodies to the nuclear envelope (NE) as identified by indirect immunofluorescence (IIF) on HEp-2 cells. Several different IIF staining patterns could be identified when antibodies to different components of the nuclear membrane (NM) and nuclear pore complexes (NuPC) were identified: a smooth membrane pattern characteristic of antibodies to nuclear lamins, a punctate pattern typical of antibodies to the nuclear pore complex and more complex patterns that included antibodies to nuclear and cytoplasmic organelles. Western immunoblotting of isolated nuclear and NE proteins and immunoprecipitation of radiolabelled recombinant proteins prepared by using the full-length cDNAs of the Translocated promoter region (Tpr), gp210 and p62 were used to identify specific autoantibody targets. Fifty-two of the 75 (70%) sera bound to Tpr, 25 (33%) bound to lamins A, B or C, 15 (20%) reacted with gp210 and none reacted with p62. Sixteen (21%) did not react with any of the NE components tested in our assays. The clinical features of 37 patients with anti-NE showed that there were 34 females and three males with an age range of 16-88 years (mean 59 years). The most frequent clinical diagnosis (9/37 = 24%) was autoimmune liver disease (ALD; two with primary biliary cirrhosis), followed by seven (19%) with systemic lupus erythematosus (SLE), four (11%) with a motor and/or sensory neuropathy, three (8%) with anti-phospholipid syndrome (APS), two with systemic sclerosis (SSc), two with Sjögren's syndrome (SjS), and others with a variety of diagnoses. This report indicates that Tpr, a component of the NuPC, is a common target of human autoantibodies that react with the NE.
Adolescent↗
Autoantibodies from primary biliary cirrhosis patients with anti-p95c antibodies bind to recombinant p97/VCP and inhibit in vitro nuclear envelope assembly.
We have reported previously that p95c, a novel 95-kDa cytosolic protein, was the target of autoantibodies in sera of patients with autoimmune hepatic diseases. We studied 30 sera that were shown previously to immunoprecipitate a 95 kDa protein from [(35)S]-methionine-labelled HeLa lysates and had a specific precipitin band in immunodiffusion. Thirteen sera were available to test the ability of p95c antibodies to inhibit nuclear envelope assembly in an in vitro assay in which confocal fluorescence microscopy was also used to identify the stages at which nuclear assembly was inhibited. The percentage inhibition of nuclear envelope assembly of the 13 sera ranged from 7% to 99% and nuclear envelope assembly and the swelling of nucleus was inhibited at several stages. The percentage inhibition of nuclear assembly was correlated with the titre of anti-p95c as determined by immunodiffusion. To confirm the identity of this autoantigen, we used a full-length cDNA of the p97/valosin-containing protein (VCP) to produce a radiolabelled recombinant protein that was then used in an immunoprecipitation (IP) assay. Our study demonstrated that 12 of the 13 (93%) human sera with antibodies to p95c immunoprecipitated recombinant p97/VCP. Because p95c and p97 have similar molecular masses and cell localization, and because the majority of sera bind recombinant p97/VCP and anti-p95c antibodies inhibit nuclear assembly, this is compelling evidence that p95c and p97/VCP are identical.
Adenosine Triphosphatases↗
Characterization of the human autoimmune response to the major C-terminal epitope of the ribosomal P proteins.
Autoantibodies to the ribosomal phospho (-P) proteins P0, P1, and P2, collectively referred to as Rib-P, are specifically found in 10-40% of patients with systemic lupus erythematosus (SLE). These antibodies are believed to be correlated with lupus nephritis, hepatitis, and central nervous system involvement. The major immunoreactive epitope of these ribosomal antigens has been localized to the carboxy terminus, which is a highly conserved domain of all three proteins and contains two phosphorylated serine residues. The phosphorylated amino acids of the P proteins are known not to be critical epitope determinants. Furthermore, epitope-mapping studies have shown that the major epitope is located within the last 11 C-terminal amino acids. Using peptide arrays we identified more precisely this shared epitope as the six C-terminal amino acids GFGLFD and elucidated the molecular recognition events of anti-Rib-P antibodies at the amino acid level. We identified Phe(111) and Phe(114) of Rib-P2 as the key residues for the interaction, with further contributions of Gly-112 and Asp-115. This amino acid stretch is also present in proteins of several pathogenic micro-organisms such as Trypanosoma cruzi, Brugia malayi, Pseudomonas aeruginosa, Candida albicans, several Leishmania species, and Bartonella henselae. Using newly developed ELISA systems with a C-terminal peptide (C22) and the recombinant proteins (P0, P1, and P2) as antigens we found a high specificity of anti-Rib-P antibodies for SLE and demonstrated positive correlations with anti-U1-C, anti-Sm-B/B' and anti-D and anti-dsDNA antibodies. The sensitivity and specificity in the peptide (C22) based assay varied between 12.8%/100% and 23.4%/96.7% for SLE, depending on the assigned cutoff. In contrast to other studies, we found no significant correlation of anti-Rib-P reactivity with central nervous system manifestations or renal involvement in SLE patients. We conclude that the epitope motif GFGLFD in the C-termini of the ribosomal P proteins is the key determinant of anti-Rib-P antibodies, and that the C22 peptide and the recombinant proteins can be used equally well for the detection of anti-Rib-P antibodies. The role of the major Rib-P epitope in the development of anti-ribosomal P antibodies and in the pathogenesis of SLE remains a subject of further investigation.
Amino Acid Sequence↗
Loss of a single allele of SHIP exacerbates the immunopathology of Pten heterozygous mice.
Phosphatidylinositol 3-kinase (PI3K) has emerged as a critical component of multiple immune system intracellular signalling pathways. The levels and relative ratios of PI3K products, phosphatidylinositol (3,4) bisphosphate (PI(3,4)P(2)) and phosphatidylinositol (3,4,5) trisphosphate (PIP(3)), are regulated by inositol phosphatases such as Pten and SHIP. Interestingly, mice heterozygous for Pten, a 3'-inositol phosphatase, develop a progressive lymphoproliferative syndrome with autoimmune features. Given the importance of PIP(3) species in regulating immune responses, we hypothesized that heterozygosity for the 5'-inositol phosphatase SHIP might exacerbate the autoimmune phenotype of Pten(+/-) mice. In keeping with this, mice heterozygous for both Pten and SHIP developed lymphoproliferation, hypergammaglobulinaemia, autoantibody titres and renal pathology that were more severe than that of Pten(+/-) mice. These results suggest that the relative levels of phosphatidylinositol phosphatases are likely critical to immune system homeostasis and they also highlight the potential for gene dosage effects in regulating susceptibility and/or severity of autoimmunity.
Animals↗
The cytoplasmic linker protein CLIP-170 is a human autoantigen.
The purpose of this study was to identify autoantigens that are recognized by human sera and are associated with a speckled cytoplasmic fluorescent staining pattern on tissue culture cells, and to determine clinical features associated with specific autoantibodies. A serum from a patient with systemic lupus erythematosus was used to identify a 3.7-kb cDNA insert from a HeLa cell expression library. The purified cDNA (VLK2.1) encoded a peptide of 1051 amino acids that shared 98.4% similarity with the carboxyl terminal portion of a previously reported 170 kD protein named cytoplasmic linker protein-170 (CLIP-170). Antibodies affinity purified with the recombinant CLIP-170 protein, the prototype human serum and a monoclonal antibody raised against CLIP-170 exhibited identical speckled staining of the cytoplasm in HEp-2 cells. The human autoantibodies reacted with the purified recombinant protein in a Western immunoblot and immunoprecipitated the in vitro translated recombinant protein. Three additional human sera also immunoprecipitated the recombinant CLIP-170 protein. The clinical diagnoses in these patients were limited scleroderma, glioblastoma and idiopathic pleural effusion. This is the first report that identifies CLIP-170 as a human autoantigen.
Autoantigens↗
Systemic sclerosis (scleroderma): specific autoantigen genes are selectively overexpressed in scleroderma fibroblasts.
The pathogenesis of systemic sclerosis (SSc) involves complex interactions between activated fibroblasts eventually leading to fibrosis, and impaired immune tolerance characterized by a variety of circulating SSc-specific autoantibodies. The expression of autoantigens in fibroblasts, a key target tissue in SSc, may play an important role in this process. To obtain a global view of this process, we examined gene expression profiles of SSc dermal fibroblasts using cDNA microarrays. The results show that dermal fibroblasts from SSc patients obtained from either affected or unaffected skin displayed a characteristic pattern of increased SSc autoantigen gene expression compared with that from normal controls. In particular, fibrillarin (p = 0.028), centromeric protein B (p = 0.01), centromeric autoantigen P27 (p = 0.042), and RNA polymerase II (220 kDa; p = 0.02) were significantly overexpressed in SSc fibroblasts. Quantitative RT-PCR confirmed overexpression of these autoantigens and also revealed increased levels of DNA topoisomerase I transcripts in SSc fibroblasts compared with normal control fibroblasts (p = 0.0318). The polymyositis/scleroderma autoantigen gene was overexpressed in some SSc patients (p = 0.09). To examine the specificity of these overexpressed autoantigen genes for SSc and its tissue specificity for fibroblasts, cDNA microarrays of dermal fibroblasts from patients with eosinophilic fasciitis and scleromyxedema were studied as well as PBMC and muscle biopsies from SSc patients. None of these tissues showed significant alterations in gene expression of SSc-specific autoantigens. Therefore, SSc-associated autoantigen genes are selectively overexpressed in SSc dermal fibroblasts, a major tissue involved in disease pathogenesis.
Autoantigens↗
Systemic sclerosis in 3 US ethnic groups: a comparison of clinical, sociodemographic, serologic, and immunogenetic determinants.
OBJECTIVE: To determine whether ethnic factors influence the presentation, serologic expression and immunogenetics of systemic sclerosis (SSc), patients from 3 ethnic groups were compared for clinical features, SSc-associated autoantibodies, and human leukocyte antigen (HLA) class II alleles. METHODS: Fifty-four Hispanics, 28 African Americans, and 79 whites from Texas with recent-onset (less than 5 years) SSc enrolled in a prospective longitudinal study were assessed for sociodemographic, clinical, immunologic, immunogenetic, behavioral, and psychologic parameters using validated instruments and standard laboratory techniques. Serologic and immunogenetic characteristics from these patients and larger retrospective SSc cohorts of the same ethnic groups also were examined. RESULTS: Hispanics and African Americans in the prospective cohort were more likely to have diffuse skin involvement, skin pigmentary changes, digital ulcers, pulmonary hypertension (African Americans), and an overall lower sociodemographic status than whites, who had more facial telangiectasia and hypothyroidism. In the larger combined prospective and retrospective groups of SSc patients, whites were likely to have more anticentromere antibodies (ACA) and African Americans more anti-U1-ribonucleoprotein (RNP) and anti-U3-RNP (fibrillarin) autoantibodies. HLA-DQB1*0301 was significantly associated with SSc per se in all 3 ethnic groups; HLA-DRB1*11 correlated with the anti-topoisomerase I antibody response, and HLA-DRB1*01, DRB1*04, and DQB1*0501 with ACA. CONCLUSIONS: Important sociodemographic, clinical, and serologic differences exist between whites, African Americans, and Hispanics, despite shared genetic (HLA class II) predisposing factors. The impact of these differences on prognosis remain to be determined.
Adult↗
Tissue transglutaminase enzyme-linked immunosorbent assay as a screening test for celiac disease in pediatric patients.
OBJECTIVE: An immunoglobulin A (IgA) anti-tissue transglutaminase antibody assay (anti-tTG) was compared with the conventional IgA anti-endomysium antibody assay (EMA) to assess its reliability as a screening test for celiac disease (CD) in a pediatric population. METHODS: Seventy-five IgA-sufficient and 2 IgA-deficient children who were scheduled for small intestinal biopsy for the evaluation of history or symptoms suggesting a diagnosis of CD were prospectively evaluated and enrolled in this study (gastrointestinal [GI] patients). In addition, 16 children with type I diabetes mellitus (DM) who had a positive EMA and a small bowel biopsy were included as a separate cohort. IgA anti-tTG was measured by enzyme-linked immunosorbent assay (ELISA), and IgA-EMA titers were determined by indirect immunofluorescence on cryopreserved sections of monkey esophagus. RESULTS: Nine of the 75 IgA-sufficient GI patients had a small bowel biopsy consistent with the diagnosis of CD. Eight of 9 IgA-sufficient patients with a positive small bowel biopsy had positive anti-tTG and EMA tests. Four IgA-sufficient patients had a false-positive anti-tTG ELISA and 2 had a false-positive IgA-EMA assay. In the IgA-sufficient patients, the sensitivity was 89% and the negative predictive value was 98% for either assay. The specificities of the IgA anti-tTG and the IgA-EMA tests were 94% and 97%, respectively (not significant). The positive predictive value of the IgA anti-tTG was 67%, compared with 80% for the IgA-EMA (not significant). In the 2 IgA-deficient children, one of whom had biopsy-proved CD, both tests were negative. In the 16 DM children 12 true- and 4 false-positive IgA anti-tTG and IgA-EMA results were identified. Three of 12 complained of GI symptoms. In follow-up, thus far, none of the DM patients with a false-positive anti-tTG have developed CD. CONCLUSIONS: The IgA anti-tTG antibody assay is equivalent to the IgA-EMA assay as a screening test for CD in IgA-sufficient pediatric patients. Intestinal biopsy remains the gold standard for the diagnosis of CD.
Abdominal Pain↗
Human autoantibodies to a novel Golgi protein golgin-67: high similarity with golgin-95/gm 130 autoantigen.
Autoantibodies to subcellular organelles have been described in patients with various systemic rheumatic diseases and our laboratories have been focused on studies of the Golgi complex as the autoimmune target. We have previously isolated and described four of the five known Golgi autoantigens reported to date. During the characterization of Golgi autoantigen golgin-95/gm130, another human cDNA that shared a significant degree of similarity in both nucleotide and amino acid sequences was identified. Analysis of cDNAs from different libraries suggested that this is a distinct gene encoding a protein of 67 kDa which has four regions with sequence identity to gm130, ranging between 42 and 60%. In this report, we describe the complete cDNA encoding a closely related Golgi protein provisionally named golgin-67. Among a group of 84 human anti-Golgi sera, five (6%) were shown to recognize golgin-67. Anti-golgin-67 human sera and affinity purified rabbit antibody to the recombinant protein gave predominant Golgi staining. Golgin-67 is thus the smallest member of a growing family of Golgi autoantigens rich in alpha-helical coiled-coil domain. The current hypothesis for the generation of autoimmune antibody to the Golgi complex is discussed.
Amino Acid Sequence↗