The Clinical Relevance of Antifibrillarin (anti-U3-RNP) Autoantibodies in Systemic Sclerosis.

Systemic sclerosis (SSc) is a heterogeneous autoimmune disease associated with several antinuclear autoantibodies useful to diagnosis and prognosis. The aim of the present multicentric study was to determine the clinical relevance of antifibrillarin autoantibodies (AFA) in patients with SSc. The clinical features of 37 patients with SSc positive for AFA (AFA+) and 139 SSc patients without AFA (AFA-) were collected retrospectively from medical records to enable a comparison between AFA- and AFA+ patients. Antifibrillarin autoantibodies were screened by an indirect immunofluorescence technique using HEp2 cells and identified by an in-house Western blot technique and/or an EliA test. Comparing AFA+ and AFA- patients, AFA+ patients were significantly younger at disease onset (36.9 versus 42.9; P = 0.02), more frequently male (P = 0.02) and of Afro-Caribbean descent (65% versus 7.7%; P < 0.001). At diagnosis, the Rodnan skin score evaluating the cutaneous manifestations was higher (13.3 versus 8.7; P = 0.01) and myositis was also more common in the AFA+ group (31.4% versus 12.2%; P < 0.01). Patients with AFA+ were not associated with diffuse cutaneous SSc or with lung involvement and no difference in survival was observed. Antifibrillarin autoantibodies are associated with patients of Afro-Caribbean origin and can identify patients with SSc who are younger at disease onset and display a higher prevalence of myositis.

Clinical significance of anti-Ro52 (TRIM21) antibodies non-associated with anti-SSA 60kDa antibodies: results of a multicentric study.

Ro52 antigen has recently been identified as TRIM21 protein, but the clinical significance of anti-Ro52/TRIM21 antibodies remains controversial. The aim of this multicentric study was to investigate the significance of anti-Ro52 antibodies without anti-SSA/Ro60 antibodies in various connective diseases. Sera were selected by each laboratory using its own method (ELISA, immunodot or Luminex technology), and then performed with ANA Screen BioPlex™ reagent (BIO-RAD). Among the 247 screened sera, 155/247 (63%) were confirmed as anti-Ro52 positive and anti-SSA/Ro60 negative. These sera were analyzed for the detection of other antibodies in relation with clinical settings. Isolated anti-Ro52 antibodies were detected in 89/155 (57%) sera. For the remaining sera (66/155), the main antibodies associations were Sm/SmRNP or Chromatin (n=38; 57%), Jo1 (n=17; 26%) and CenpB (n=9; 14%). Clinical data from the 155 patients showed high prevalence in autoimmune diseases (73%) including myositis or dermatomyositis (n=30), lupus (n=23); Sjögren and/or sicca syndrome (n=27); CREST or Systemic sclerosis (n=11) and autoimmune hepatitis (n=11). We found that pulmonary manifestations were often associated with the presence of anti-Ro52 antibodies (n=34, 22%), in addition with anti-tRNA synthetases, anti-SRP or anti-Ku antibodies (18/34) or isolated in half of cases (16/34). Separate detection of anti-Ro52 antibodies might be useful in related antisynthetase syndrome diagnosis. The presence of anti-Ro52 antibodies should probably precede development of autoimmune disease and must induce sequential follow-up of positive patients, particularly in interstitial lung disease progression.

Prevalence and clinical features of celiac disease in 950 children with type 1 diabetes in France.

UNLABELLED: The prevalence of celiac disease is higher in children with type 1 diabetes mellitus (DM) than in the general pediatric population, but may vary widely across countries. Sensitive and specific antibody tests are available for detecting celiac disease. AIMS: To evaluate the prevalence in France of histologically documented celiac disease in a vast cohort of children with type 1 DM, and to describe the features of celiac disease and treatment response. METHODS: Retrospective cohort study of 950 children with type 1 diabetes seen between 1994 and 2001. Antibodies to gliadin, reticulin, endomysium and transglutaminase were looked for one to seven times in each patient. RESULTS: Fifteen patients (1.6%) had biopsy-confirmed celiac disease. Symptoms led to the diagnosis in six patients (mean age, 7 years) and screening tests in nine patients (mean age, 11 years). Anti-endomysium antibodies were consistently positive. Tests for HLA-DQB1 0201 and/or 0302 were positive. Anti-endomysium antibody seroconversion was seen in two patients, 2 and 6 years, respectively, after the diagnosis of diabetes. In another patient, the biopsy became abnormal 6 years after the first positive anti-endomysium antibody test (latent form). After a mean of 3 years on a gluten-free diet, significant increases were noted in body weight (P=0.04) and insulin dose (P=0.05); clinical symptoms completely resolved in five of the six symptomatic patients. CONCLUSIONS: The prevalence of celiac disease is higher in children with type 1 DM than in the general pediatric population. Serological screening is useful for diagnosing asymptomatic celiac disease, detecting seroconversion and monitoring latent forms of disease.

Update on Anti-Saccharomyces cerevisiae antibodies, anti-nuclear associated anti-neutrophil antibodies and antibodies to exocrine pancreas detected by indirect immunofluorescence as biomarkers in chronic inflammatory bowel diseases: results of a multicenter study.

AIM: Anti-Saccharomyces cerevisiae antibodies (ASCA), anti-nuclear associated anti-neutrophil antibodies (NANA) and antibodies to exocrine pancreas (PAB), are serological tools for discriminating Crohn's disease (CrD) and ulcerative colitis (UC). Like CrD, coeliac disease (CoD) is an inflammatory bowel disease (IBD) associated with (auto) antibodies. Performing a multicenter study we primarily aimed to determine the performance of ASCA, NANA and PAB tests for IBD diagnosis in children and adults, and secondarily to evaluate the prevalence of these markers in CoD. METHODS: Sera of 109 patients with CrD, 78 with UC, 45 with CoD and 50 healthy blood donors were retrospectively included. ASCA, NANA and PAB were detected by indirect immunofluorescence (IIF). RESULTS: ASCA+/NANA- profile displayed a positive predictive value of 94.2% for CrD. Detection of ASCA was correlated with a more severe clinical profile of CrD and treatment of the disease did not influence their serum levels. ASCA positivity was found in 37.9% of active CoD. PAB were found in 36.7% CrD and 13.3% CoD patients and were not correlated with clinical features of CrD, except with an early onset of the disease. Fifteen CrD patients were ASCA negative and PAB positive. CONCLUSION: ASCA and PAB detected by IIF are specific markers for CrD although their presence does not rule out a possible active CoD. The combination of ASCA, NANA and PAB tests improves the sensitivity of immunological markers for CrD. Repeating ASCA, NANA, and PAB testing during the course of CrD has no clinical value.

Diagnostic value of anti-F-actin antibodies in a French multicenter study.

According to international criteria, autoimmune hepatitis (AIH) type 1 is characterized by the presence of antinuclear or anti-smooth muscle antibodies (SMA) with F-actin specificity. SMA have been found in 85% of AIH patients, but are not specific to this disease, and anti-F-actin specificity is not always verified when SMA are detected. The objective of this study was to determine the diagnostic value of anti-F-actin antibodies in a large population. A multicenter study involving 12 clinical centers was performed. Patients were selected on the basis of the presence of F-actin SMA detected by indirect immunofluorescence (IIF) on rat liver-kidney-stomach sections and was confirmed by IIF on Hep2 cells treated with colchicine, or F-actin dot-blot. The clinical status of patients was determined from their medical records. One hundred sixty-eight patients were included: 76% women, 24% men; mean age of 45 years (range, 2-88 years), with a bimodal age distribution. Sixty percent had AIH type 1, and 40% had another disease. In the group of women younger than 25 years, 90% had AIH type 1. Other pathologies associated with antiactin were other liver diseases (19%), including viral hepatitis C (7%), and non-liver diseases (21%), including connective tissue diseases (12%). Antibody titers were higher in AIH than in other diseases. Antiactin antibodies are of major diagnostic value in AIH, especially in young women; they may be found in other disease settings, but mostly at low levels.

[Analytic study of dot blotting for the detection of anti-Jo-1, anti-M2, anti-ribosomes and anti-LKM]. / Etude analytique d'un dot blot pour la détection des auto-anticorps anti-Jo-1, anti-M2, anti-ribosomes et anti-LKM1.

The Cyto-Dot 4 HM043 kit commercialised by BMD, has replaced the Cyto-Dot HM010 kit that allowed three auto-antibodies detection (anti-Jo-1, anti-M2 and anti-ribosomal protein). Detection of anti-LKM1 auto-antibody was added. These four auto-antibodies have in common only the intracytoplasmic localisation of their respective antigen. The aim of our study was to evaluate this new kit using 104 sera and to compare our results with reference techniques (indirect immunofluorescence IF for anti-M2, anti-ribosomal protein and anti-LKM1, double immunodiffusion ID for anti-Jo-1 and anti-LKM1, western blotting WB for anti-M2) and with Cyto-Dot HM010. The one hundred and four sera were divided into five groups: Group I (n = 12) with anti-Jo-1 detected by ID; Group II (n = 28) with 26 anti-M2 positive by IF and WB, 2 anti-M2 positive only by WB; Group III (n = 10) with anti-ribosomal protein detected by IF 5 of which precipitated by ID; Group IV (n = 32) with anti-LKM1 by IF and ID divided into 18 AIH2 and 14 HCV; Group V (n = 22) consisting of 14 healthy individuals and 8 patients with hypergammaglobulinemia. Results of this study are similar to those of Cyto-Dot HM010 for the three auto-antibodies already in use. Cyto-Dot 4 is a very good anti-LKM1 confirmation method as it is ID.

A 10 year follow up study of patients transplanted for autoimmune hepatitis: histological recurrence precedes clinical and biochemical recurrence.

BACKGROUND AND AIM: Autoimmune hepatitis (AIH) has been reported to recur after orthotopic liver transplantation (OLT) in 10-35% of patients in small series with a short follow up. The aim of the present study was to examine the clinical and histological outcome more than 10 years after OLT for AIH. PATIENTS AND METHODS: Seventeen women with a mean age of 30 (12) years at the time of OLT, selected from among 44 patients transplanted for AIH, were followed for more than 10 years. The criteria for definite AIH, as established by the International Autoimmune Hepatitis Group, were met in every case. Liver biopsies were performed 1, 2, 5, and 10 years after OLT, and when indicated by abnormal liver function tests. Specimens were examined for evidence of recurrent AIH, namely interface hepatitis, lobular activity, portal lymphoplasmocytic infiltration, and fibrosis. Other signs of recurrence included hypertransaminasaemia, serum autoantibodies, and the response to steroid reintroduction or significant steroid dose increments. RESULTS: AIH recurred in 7 (41%) of 17 patients. In four patients histological abnormalities were detected by means of protocol biopsies 1-5 years before the onset of biochemical abnormalities. Two patients developed severe recurrences after 10 and 15 years, respectively, and required treatment with steroids and tacrolimus. In the other three patients histological recurrence was detected 0.6-3 years post-OLT, concomitantly with biochemical abnormalities. CONCLUSIONS: AIH recurred in 41% of patients followed for more than 10 years after OLT. As histological signs preceded biochemical abnormalities in four patients (23.5%), regular liver biopsy is warranted after OLT. Detection of isolated histological signs may call for closer follow up and/or a change in immunosuppressive therapy.

Anticardiolipin antibodies in patients with multiple sclerosis do not represent a subgroup of patients according to clinical, familial, and biological characteristics.

BACKGROUND: In multiple sclerosis (MS), case control studies have shown that anticardiolipin antibodies (aCL Ab) are more frequent than in the general population and that aCL Ab positivity may be associated with specific clinical characteristics. OBJECTIVES: To determine whether patients with MS who are positive for aCL Ab have specific characteristics. METHODS: 285 consecutive patients with MS were tested for aCL Ab positivity. Patients also underwent complete autoimmune screening and were systematically evaluated for clinical characteristics and individual or family history of autoimmune disease. RESULTS: aCL Ab positivity was found in 42 patients (15%). The main isotype was aCL IgM (32 patients, 11%). Demographics and clinical characteristics including sex, age at onset, course of the disease, expanded disability status scale score, and progression index were not different between aCL Ab positive and aCL Ab negative patients. Clinical systems involved at onset or during the course of the disease were not different from what is usually observed in MS. aCL Ab positivity was not associated with an increased frequency of autoimmune disease and was not predictive of a family history of autoimmune disease. Patients positive for aCL IgM were more frequently positive for the presence of non-organ specific antibodies (53% v 39%, respectively, p = 0.02). CONCLUSIONS: These results do not support the hypothesis that patients with MS with aCL Ab constitute a subgroup of MS according to demographic clinical and familial characteristics. The greater frequency of other antibodies in aCL Ab positive patients suggests that they only reflect a more general autoimmune activation in MS.

Polyspecificity of antimicrosomal thyroid antibodies in hepatitis C virus-related infection.

OBJECTIVES: The outcome of dysthyroidism and the presence of antithyroid antibodies in patients with chronic hepatitis C virus (HCV) infection receiving interferon-alpha therapy is clearly established. However, the prevalence and the specificity of antithyroid antibodies in HCV patients before interferon-alpha therapy remain controversial. The aim of the present study is to clarify within a large population of HCV patients the prevalence of antithyroid antibodies before interferon-alpha therapy and to determine whether their immunodominant antigen is the same as described in autoimmune thyroiditis. METHODS: Sera from 99 patients with chronic hepatitis C before (n = 99) and after (n = 37) interferon-alpha treatment were investigated for the presence of antimicrosomal and antithyroperoxidase antibodies assessed by indirect immunofluorescence and ELISA, respectively. Dot blotting on human thyroid lysate was designed to further characterize these autoantibodies. Data were compared to those obtained with sera of patients with autoimmune thyroiditis (n = 75) and healthy subjects (n = 96). RESULTS: In HCV patients, antimicrosomal antibodies were found with a higher proportion before interferon-alpha therapy (12.1%) than after therapy (8%). Thyroperoxidase constitutes the main antigen in only 4% before treatment, a prevalence similar to that observed in healthy controls. CONCLUSIONS: The prevalence of antithyroid antibodies is low in patients with chronic hepatitis C before interferon-alpha therapy. Thyroperoxidase may not be their main target. Further studies are required to determine whether HCV infection leads to a breakdown of tolerance to a thyroid self-protein other than thyroperoxidase.

Successful tacrolimus therapy for a severe recurrence of type 1 autoimmune hepatitis in a liver graft recipient.

A 34-year-old woman underwent orthotopic liver transplantation (OLT) for decompensated type 1 autoimmune hepatitis (AIH). She was administered standard triple-drug immunosuppressive therapy (cyclosporine, steroids, and azathioprine). Ten years after OLT, she developed a recurrence of AIH, with emergence of serological markers of autoimmunity (high anti--smooth muscle antibody [ASMA] titer, high serum gamma globulin level), abnormal liver function test results, and characteristic histological features on liver biopsy. Despite intensified steroid therapy, her clinical and liver function deteriorated. The onset of cutaneous alternariosis led to a steroid dose reduction and cyclosporine replacement by tacrolimus. Clear-cut amelioration was observed, with an improvement in liver function test results and reduction in ASMA titer. One year after the recurrence of AIH, the patient has normal liver function and physical findings. Tacrolimus therefore may be effective in patients with severe recurrent autoimmune liver disease. Further studies are needed to assess tacrolimus therapy in patients who fail to respond to standard immunosuppressive therapy.

Familial lupus erythematosus. Clinical and immunologic features of 125 multiplex families.

Evidence for a genetic susceptibility to systemic lupus erythematosus (SLE) in humans is based on the high concordance rate observed in identical twins and on the relatively high incidence of familial cases. Although recent genetic studies have lead to significant advances in the identification of new susceptibility genes in SLE, no large clinico-pathologic study of familial SLE has been reported to date. In the present study, we describe the main clinical and immunologic features of 125 lupus multiplex families including at least 2 cases of SLE and/or discoid lupus erythematosus (DLE), recruited through a French national survey starting in July 1997. Medical records of all affected members were reviewed by the same investigator, all available family members were interviewed using the same standardized procedure, and blood was drawn for autoantibodies typing. Clinical and immunologic features of 90 probands from multiplex SLE families were compared with those of 100 sporadic SLE patients sharing the same French Caucasian origin. The 125 lupus multiplex families included 282 affected members (2.3 patients per family); of the 125 families, 96 were of French Caucasian origin. One hundred multiplex families included 2 affected relatives, while 25 included 3 or more affected individuals. The relationship between affected members was sibs (45%), parent-offspring (31%), and second-degree (24%). An autosomal dominant mode of inheritance was strongly suggested in 1 extended pedigree with 6 clinically affected members, and a recessive pattern was suspected in 5 other families. No obvious mode of inheritance could be suspected in most of the remainder. Among French Caucasians, sex ratio, mean age at onset, and clinical and biologic SLE-related manifestations were not significantly different in multiplex compared with sporadic SLE cases. The analysis of these 125 multiplex families suggests a genetic heterogeneity that should be considered for ongoing genomic screening.

[Autoimmune hepatitis. Physiopathologic, clinical, histological, and therapeutic features]. / Hépatites auto-immunes. Aspects physiopathologiques, cliniques, histologiques et thérapeutiques.

Autoimmune hepatitis is characterized by an inflammation of the portal tract with lymphocytes and plasma cells, an hypergammaglobulinemia and a variety of circulating autoantibodies. The presence of smooth muscle antibodies and/or antinuclear antibodies define type 1. Type 2 is characterized by the presence of liver-kidney--microsomal antibodies. Environmental, genetic and infectious factors may explain the autoreactivity of T cells. Different non specific clinical features may be present. Sometimes the presentation may be an acute hepatitis; in the remainder, the disease may not be recognized until liver damage is advanced. Hypergammaglobulinemia and presence of circulating autoantibodies are the key for diagnosis. The association of prednisolone in combination with azathioprine remains the established treatment. If relapse or non response occur, other immunosuppressive therapy such as cyclosporin may be useful. Liver transplantation is reserved for (sub)fulminant forms and end stage liver disease.

Antibodies to soluble liver antigen: an additional marker in type 1 auto-immune hepatitis.

BACKGROUND/AIMS: Auto-immune hepatitis patients are divided into two well-defined subgroups on the basis of immunoserological markers, i.e. anti-actin cable and/or anti-nuclear antibodies for the auto-immune hepatitis type 1, anti-liver/kidney microsome type 1 and/or anti-liver cytosol type 1 for the autoimmune hepatitis type 2. Controversial antibodies to a soluble liver antigen have been proposed as a diagnostic marker for the putative auto-immune hepatitis type 3. The aim was to investigate the implication of anti-soluble liver antigen antibodies in the diagnosis of auto-immune hepatitis and their ability to define auto-immune hepatitis type 3. METHODS: Sera from 483 patients with hepatic and non-hepatic diseases, and 102 sera from blood donors were analyzed by an inhibition capture enzyme-linked immunosorbent assay. RESULTS: Anti-soluble liver antigen antibodies were found in 13 of the 106 (12%) auto-immune hepatitis type 1 patients and 10 of the 49 (20%) cryptogenic hepatitis patients tested. In contrast, they were not detected in auto-immune hepatitis type 2 (n=54), primary sclerosing cholangitis (n=37), primary biliary cirrhosis (n=52), hepatitis C virus infection (n=105), alcoholic hepatitis (n=25), various non-hepatic autoimmune disorders (n=55) and in healthy blood donors (n=102). The clinical and biological features of antisoluble liver antigen-seropositive patients were similar to those of auto-immune hepatitis type 1 and did not distinguish a subgroup of auto-immune hepatitis. CONCLUSION: The data support the concept that antisoluble liver antigen-positive cryptogenic hepatitis is similar to auto-immune hepatitis type 1. Anti-soluble liver antigen antibodies can be considered as an additional and specific auto-immune hepatitis type 1 diagnostic marker.

Autoantibodies associated with acute rejection after liver transplantation for type-2 autoimmune hepatitis.

Autoantibodies, markers of autoimmune diseases, can also be detected in chronic allograft rejection. However, the appearance of these autoantibodies in acute rejection after orthotopic liver transplantation has not yet been reported. Liver-kidney-microsome type-1 (LKM-1) antibodies directed against the autoantigen cytochrome CYP2D6 define a group of patients with autoimmune hepatitis type-2 (AIH-2), distinct from autoimmune hepatitis type-1 (AIH-1) in which anti-nuclear antibodies and anti-smooth muscle antibodies (SMA) with actin specificity are present in patient sera. Autoantibodies were studied by the quantitative CYP2D6 radioligand assay (RLA) that uses a radiolabeled CYP2D6 as antigen, immunoblotting using recombinant CYP2D6 protein and human liver microsomal and cytosolic fractions, and indirect immunofluorescence (IIF) using rat kidney-stomach-liver cryostat sections. In addition, the specificity of anti-SMA was detected by IIF on HEp2 cell line harvested with colchicin. This report describes the time course of CYP2D6 antibodies and the appearance of anti-SMA (without anti-actin, cytokeratin and vimentin reactivity) associated with acute rejection during a 2-year follow-up, in a patient who underwent transplantation at end-stage type 2 autoimmune hepatitis. In addition, we report a new reactivity against an unknown 40-kDa protein using a rat cytosolic fraction. The detection of autoantibodies in sequential samples may be important to better predict rejection or relapse, and to establish adequate therapy.

[Clinical significance of antiribosomal antibodies. Study Group on Autoimmunity (GEAI)]. / Signification clinique des anticorps antiribosomes. Groupe d'étude auto-immunité (GEAI).

PURPOSE: Autoantibodies directed against the ribosomal P proteins, P0, P1 and P2 (anti-P), have been related to lupus-related psychosis and/or depression. The diagnostic value of antibodies directed against other ribosomal proteins or 28S RNA (anti-no-P) remains unknown. A multicenter study including ten centers belonging to the study group for autoimmune diseases (GEAI) was conducted in order to determine the diagnostic value of anti-P and anti-no-P antibodies in a large population of patients. METHODS: The patients were selected on the basis of the presence of serum anti-ribosomal antibodies detected by indirect immunofluorescence (IF) on rat liver/kidney/stomach/pancreas sections and human HEp2 cells. The clinical course of all patients was studied using a predetermined survey. The specificity of anti-P antibodies were determined by Western blot. RESULTS: Anti-ribosomal antibodies were found in 82 patients. Fifty-five of them had systemic lupus erythematosus and 27 had another disease. Only 54% of the anti-ribosomal antibodies detected by IF were anti-P and were found in 69% of the patients with systemic lupus erythematosus. Anti-no-P antibodies (46%) were preferably detected in patients who suffered from another disease (78%). In patients with systemic lupus erythematosus, neurological and psychiatric disorders were more frequent in the no-P group (47% vs. 16%, P < 0.01) than arthritis, which was found more frequently in the P group (78% vs. 53%, P < 0.05). CONCLUSION: Anti P antibodies do not constitute a specific diagnostic marker of systemic lupus erythematosus, and lupus-related neuropsychiatric disorders would be preferably associated with the presence of anti no-P antibodies.

[Autoantibodies in hepatology]. / Auto-anticorps en hépatologie.

The diagnosis of autoimmune liver disease (primary biliary cirrhosis, autoimmune hepatitis, and primary sclerosing cholangitis) can be made by assaying specific autoantibodies in the serum. A review is presented of these antibodies, the methods used to detect them, and the antigens identified to date. Hepatitis C is the most common cause of autoantibody production in liver diseases and is also discussed.

Habitual abortions in 678 healthy patients: investigation and prevention.

The objective of this study of patients with habitual abortion (HA), was to determine their autoimmune profile and to try to prevent new abortions using low-dose aspirin for 7 months with prednisone in the first trimester only, or with low-dose aspirin alone. A total of 678 healthy patients with three or more HA were investigated for antiphospholipid antibodies, antinuclear and antithyroid antibodies. Among these patients, 277 pregnant women were treated, 214 were given prednisone and aspirin (161 autoantibody-negative and 53 autoantibody-positive women), and 63 autoantibody-negative women received aspirin alone. Autoantibodies were present in 33.9% of the patients, in 82.6% of them anticardiolipin antibodies were found to be isolated or associated with antiprothrombin, antithyroid, circulating anticoagulant, antinuclear or anti-beta2 glycoprotein 1 antibodies. In autoantibody-negative pregnant women treated by prednisone and aspirin or aspirin alone, the success rate of live births was 90.7% (146 out of 161) and 74.6% (47 out of 63) respectively (P < 0.01). In autoantibody-positive patients treated with prednisone and aspirin the success rate was 84.9% (45 out of 53) (not significant). Prednisone and aspirin seemed to be as efficient in autoantibody-negative or positive women but better than aspirin alone in autoantibody-negative women. A double-blind trial is in progress to confirm these results.

Autoepitope mapping and reactivity of autoantibodies to the dihydrolipoamide dehydrogenase-binding protein (E3BP) and the glycine cleavage proteins in primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by the presence of antimitochondrial antibodies (AMA) directed primarily against the E2 subunits of the pyruvate dehydrogenase complex, the branched chain 2-oxo-acid dehydrogenase complex, the 2-oxoglutarate dehydrogenase complex, as well as the dihydrolipoamide dehydrogenase-binding protein (E3BP) of pyruvate dehydrogenase complex. The autoantibody response to each E2 subunit is directed to the lipoic acid binding domain. However, hitherto, the epitope recognized by autoantibodies to E3BP has not been mapped. In this study, we have taken advantage of the recently available full-length human E3BP complementary DNA (cDNA) to map this epitope. In addition, another lipoic binding protein, the H-protein of the glycine cleavage complex, was also studied as a potential autoantigen recognized by AMA. Firstly, the sequence corresponding to the lipoic domain of E3BP (E3BP-LD) was amplified by polymerase chain reaction and recombinant protein and then purified. Immunoreactivity of 45 PBC sera (and 52 control sera) against the purified recombinant E3BP-LD was analyzed by enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Secondly, reactivity of PBC sera was similarly analyzed by immunoblotting against H-protein. It is interesting that preabsorption of patient sera with the lipoic acid binding domain of E3BP completely removed all reactivity with the entire protein by immunoblotting analysis, suggesting that autoantibodies to E3BP are directed solely to its lipoic acid binding domain. Fifty-three percent of PBC sera reacted with E3BP-LD, with the majority of the response being of the immunoglobulin G (IgG) isotype (95%). Surprisingly, there was little IgM response to the E3BP-LD suggesting that the immune response was secondary because of determinant spreading. In contrast, H-protein does not appear to possess (or expose) autoepitopes recognized by PBC sera. This observation is consistent with structural data on this moiety.

Description of a new DRB1*11 allele (DRB1*1132).

We describe a new DRB1*11 allele which is similar to DRB1*11011 except at codon 74, where a GCG is changed for a GTG leading to an alanine/valine substitution. This new allele was carried by a Caucasian patient suffering from rheumatoid arthritis and by her healthy daughter. The motif at codon 74 of the new DRB1*11 is not found in any other known DRB alleles, nor among the published DQA1, DQB1, DPA1 or DPB1 alleles, and therefore suggests a mechanism of point mutation.