Differences in clinical sensitivity of ELISA tests for autoantibodies with human and bovine extractable nuclear antigens

Bovine antigens are routinely used in indirect ELISA tests to detect autoantibodies against extractable nuclear antigens (ENA). Here we investigate the difference in clinical sensitivity between ELISA tests prepared with native human and bovine antigens. SSA and SSB were obtained from spleen and nRNP/Sm complex from thymus. Each antigen was extracted with the same immunoaffinity column. ELISA tests with human and bovine antigens were set up under the same conditions of clinical specificity established on 50 blood bank donors. Of 109 random SLE and Sjogren's syndrome sera 49% and 35% were positive, respectively, for human and bovine SSA, 26% and 16% for SSB. Of 98 random SLE sera 52% and 41% were positive for human and bovine nRNP/Sm, respectively. A few specimens reacted only with bovine antigens, probably false positive reactions. The relative clinical sensitivity for all specimens identified as positive by human and/or bovine antigens was significantly higher with human than with bovine SSA, (93% vs 67%; P<0.001, chi2), SSB (93% vs 50%; P<0.001), and for nRNP/Sm (96% vs 75%; P<0.01). However, for values that exceeded 2.5-4 times the upper normal limit, the levels were similar for human and bovine antigens. We concluded that native human antigens offer clinical sensitivity superior to native bovine antigens for the measurement of anti-ENA antibodies by ELISA.     

HLA antigens in Italian patients with systemic lupus erythematosus: evidence for the association of DQw2 with the autoantibody response to extractable nuclear antigens

In order to verify the hypothesis that Italian patients with systemic lupus erythematosus (SLE) may be immunogenetically distinct from SLE patients born in other regions, we investigated the HLA class I and II antigens and their relation with the various autoantibodies characteristic of the disease in an Italian SLE population. Forty-four SLE patients were typed for HLA-A, -B, -C, -DR and -DQ antigens; sera from the same patients were tested for the presence of antibodies to the nuclear or cytoplasmic antigens Ro/SSA, La/SSB, Sm and RNP (ENA). Results of HLA typing showed that the frequencies of DR3 and DQw2 were increased in patients compared with controls. Analysis of the correlations between HLA antigens and anti-ENA antibodies showed that both DQw2 and DR3 were increased in patients with anti-Ro and/or antiLa antibodies, while in patients with anti-Sm and/or antiRNP antibodies the DQw2 and DR4 were found to be increased. Only DQw2 was found to be significantly increased in anti-ENA positive patients. These results might suggest that Italian patients with SLE are, at least in part, different from lupus patients living in other geographical areas and suggest the association of DQw2 with the autoantibody response to ENA in SLE.     

A model for disease heterogeneity in systemic lupus erythematosus. Relationships between histocompatibility antigens, autoantibodies, and lymphopenia or renal disease

We composed a model from autoimmune serologic findings, HLA antigens, and clinical findings that explains, at least partially, the clinical heterogeneity of 40 patients with systemic lupus erythematosus (SLE). In these patients, anti-RO (SS-A) was related to the HLA-DQ1/DQ2 heterozygotes, anti-La (SS-B) was related to HLA-B8 and HLA-DR3, and anti-nuclear RNP (Sm) was related to HLA-DR4. Lymphopenia was associated with anti-Ro (SS-A) and, secondarily, with anti-single-stranded DNA. Renal disease in these SLE patients was inversely associated with anti-La (SS-B) and was positively associated with anti-double-stranded DNA. There were no associations between the HLA antigens and these clinical manifestations. The results support a model of disease expression in which individuals are nonspecifically potentiated for SLE. Their HLA antigen composition influences the production of particular autoantibodies that are related in complex ways to the different particular clinical findings of SLE manifested in individual patients.     

Increased prevalence of autoantibodies to ku antigen in African American versus white patients with systemic lupus erythematosus

OBJECTIVE: To investigate whether the widely varying estimates of the prevalence of anti-Ku autoantibodies are explained by racial/ethnic differences. METHODS: Consecutive African American or white patients who met the 1982 criteria for systemic lupus erythematosus (SLE) and who were evaluated over 10 years in North Carolina, Florida, and New York were tested by immunoprecipitation of K562 cell extract for anti-Ku as well as anti-nuclear RNP (nRNP)/Sm, anti-Ro/SSA, and anti-La/SSB autoantibodies. RESULTS: Anti-Ku autoantibodies were detected in sera from 18 of 155 African American patients with SLE (12%) versus 0 of 126 white patients (P < 0.0001, by Fisher's exact test). Anti-nRNP (63% versus 16%; P < 0.0001) and anti-Sm (23% versus 7%; P < 0.0004) autoantibodies were also more common in the African American subset. The 2 groups had comparable frequencies of anti-Ro/SSA and anti-La/SSB autoantibodies. CONCLUSION: Anti-Ku antibodies are common in African American patients with SLE but rare in whites, probably explaining the different estimates of their prevalence. In African Americans, the frequency is comparable with that of anti-La/SSB. Along with anti-Ku, anti-nRNP and anti-Sm autoantibodies are also overrepresented in African Americans, suggesting that a group of specificities is characteristically associated with SLE in African Americans.     

Clinical value of an integrated ELISA system for the detection of 6 autoantibodies (ssDNA, dsDNA, Sm, RNP/Sm, SSA, and SSB)

An ELISA panel assay (ANA/6) which simultaneously detects IgG autoantibodies against 6 antigens (ssDNA, dsDNA, Sm, RNP/Sm, SSA, and SSB) was evaluated with sera from 98 patients with systemic lupus erythematosus (SLE) and related conditions, 68 disease controls, who were positive or negative by fluorescent ANA (FANA), and 100 healthy controls. The antigen panel specifically identified the particular autoantibodies present and had a high level of sensitivity which was reflected by the frequency of detection of autoantibodies in different patient groups. All active patients with SLE were positive for at least one autoantibody and 80% of these patients had 3 or more autoantibodies compared to only 20% of inactive patients. A large heterogeneity in antibody profiles was also noted. About 90% of patients with positive FANA, but no detectable autoimmune rheumatic disorder, i.e., false positive, were negative by the panel. A new method of standardization was designed to use the ANA/6 quantitatively. Very large differences in the level of all 6 autoantibodies were observed between sera from patients with active and inactive SLE, suggesting a potential usefulness of ANA/6 for patient management.     

Autoantibodies against alpha-fodrin in Sjögren's syndrome with neurological manifestations

OBJECTIVE: To investigate the diagnostic value of autoantibodies against alpha-fodrin in patients with Sj?gren's syndrome (SS) with neurological manifestations compared to SS patients without neurological manifestations, a control group, and patients with other neurological autoimmune diseases including systemic lupus erythematosus (SLE) with neurological manifestations and multiple sclerosis (MS). METHODS: We evaluated alpha-fodrin autoantibodies in 31 patients with SS with neurological manifestations, 53 SS patients without neurological symptoms, 38 patients with SLE, 60 with MS, and 160 controls. RESULTS: Twenty of the 31 SS patients with neurological manifestations (64.5%) had an increased concentration of IgA and/or IgG anti-alpha-fodrin. This was not statistically different from that of SS patients without neurological symptoms (73.6%), but was higher than the number with SSA/SSB antibodies, which were found in 15 (48%) of our SS patients without neurological manifestations. When the results of the 2 tests were combined, 28 of the 31 (90.3%) patients had positive autoantibodies (alpha-fodrin and/or SSA/SSB). Alpha-fodrin antibodies were increased in 8 (13.3%) of the 60 patients with MS, in 6 (15.7%) of 38 patients with SLE, and in 10 (6.3%) of 160 controls. CONCLUSION: Our results confirm that alpha-fodrin antibodies are an additional diagnostic tool for SS. This test is of particular interest for patients with SS with neurological manifestations, in whom anti SSA/SSB antibodies are less frequently found.     

PREVALENCE AND CLINICAL SIGNIFICANCE OF ANTIBODIES TO RIBONUCLEOPROTEINS IN SYSTEMIC LUPUS ERYTHEMATOSUS IN MALAYSIA

One hundred and seventy patients with systemic lupus erytbematosus(SLE) were studied for the prevalence of antibodies to the smallRNA-associated proteins Ro/SSA, La/SSB, Sm, UIRNP and Sm. Therelationship of these autoantibodies to different races, sexesand clinical manifestations of SLE was evaluated. Passive immunodiffusionwas employed using human spleen extract as antigen source forRo and rabbit thymus extract for La, Sm and UIRNP. We foundthe prevalence of antibodies to be as follows: anti-Ro/SSA,36%; anti-La/SSB, 8%; anti-Sm, 15%; anti-UIRNP, 21%. Exceptfor a low prevalence of anti-La, the prevalence of these antibodieswas similar to that in Western studies. The prevalence of anti-Ro/SSAis similar to that reported in the Western studies, but lowerthan that reported in other Oriental patients from Singaporeand Hong Kong. Linkages of anti-Ro with anti-La antibodies wereusual; however, although anti-Sm antibodies were usually associatedwith anti-UIRNP, they were more frequently associated with anti-Roantibodies. The Malay patients had a high prevalence of anti-UIRNPcompared to other races. No gender difference was detected.Anti-Sm antibody was associated with scrositis and anti-UIRNPantibodies with Raynaud's phenomenon. No association was foundbetween the presence of skin, renal or cerebral manifestationsand any specific antibodies or combination of antibodies. KEY WORDS: Systemic lupus erythematosus, Racial comparison, Ro/SSA, La/SSB, Sm, UIRNP     

HLA antigens associated with systemic lupus erythematosus in Japan

We studied whether or not HLA-A,B,C and DR antigens were associated with clinical and immunological findings in 116 patients with systemic lupus erythematosus (SLE) in Japan. SLE patients tended to be associated with HLA-DR2, compared with 75 healthy individuals. Among the SLE patients, there was an association between HLA antigens and the presence or absence of certain clinical or immunological features. Different HLA antigens might have a predictive value for SLE and/or the same clinical and immunological abnormalities between Caucasian and Japanese SLE patients.     

The use of immunoblotting to detect antibodies to nuclear and cytoplasmic antigens. Clinical and serological associations in rheumatic diseases

Using the immunoblotting technique, sera from 433 patients with rheumatic diseases were screened for the presence of antibodies against several nuclear and cytoplasmic antigens, such as RNP, Sm, Ro(SSA), La(SSB), CR-19 (centromeric antigen), Topo-1 (Scl-70), Jo-1, histone and 56 kD. At the same time clinical data from these patients were collected without prior knowledge of the immunoblotting results. Syndrome-specific autoantibodies were found for mixed connective tissue disease (antibodies against the RNP related 70 kD antigen), for CREST (anti-CR-19 antibodies), for diffuse scleroderma (anti-Topo-1 antibodies) and for polymyositis (anti-Jo-1 antibodies). Almost all specific autoantibodies were present exclusively in patients with a connective tissue disease. Controls were only in a few cases positive for antihistone and anti-56 kD antibodies. Associations of specific autoantibodies with clinical and laboratory features of the patients were mostly as expected. However, some unexpected associations were found, for example polymyositis and calcinosis with anti-Sm antibodies, sicca symptoms with anti-centromere antibodies and leucopenia with Ro(SSA) and La(SSB).     

Is immunogenetic susceptibility to neuropsychiatric systemic lupus erythematosus (SLE) different from non-neuropsychiatric SLE?

OBJECTIVES: To analyse frequency of HLA class II antigens (DR and DQ) and lymphocytotoxic autoantibodies in patients with systemic lupus erythematosus (SLE) and subsets with or without neuropsychiatric involvement. METHODS: Ninety three patients with SLE (42 with neuropsychiatric features) were typed for HLA class II antigens and investigated for the presence of lymphocytotoxic autoantibodies by a complement dependent microlymphocytotoxicity assay. A total of 191 controls of similar ethnic background were also typed for HLA antigens. RESULTS: HLA-DR3 antigen was increased in the total group of patients with SLE (p = 0.003) and in the neuropsychiatric group (p = 0.002). HLA-DR4 antigen frequency was increased in non-neuropsychiatric patients (p = 0.001) and decreased in patients with neuropsychiatric SLE (p = 0.0005). Comparisons of HLA frequencies between subgroups of patients showed decreased HLA-DR4 (p < 0.0001) and increased HLA-DR9 and HLA-DQ2 antigens (p = 0.0008 and 0.005 respectively) in the neuropsychiatric group. The frequency of lymphocytotoxic autoantibodies was increased in neuropsychiatric patients with SLE having HLA-DR9 specificity (p = 0.04). CONCLUSION: HLA-DR4 may have a protective specificity for the development of neuropsychiatric features of SLE and HLA-DR9, in addition to HLA-DR3, and the presence of lymphocytotoxic auto-antibodies may predispose to neuropsychiatric abnormalities.     

HLA alloantigens in Greek patients with systemic lupus erythematosus

The frequency of the HLA-A, -B and -DR alloantigens was studied in 74 unselected, consecutive, unrelated Greek patients with systemic lupus erythematosus (SLE) and the results were compared with those of healthy controls (380 for the class I antigens and 154 for the class II antigens). No statistically significant differences were noted between patients and controls regarding the prevalence of any class II antigen. Furthermore, no such differences were observed between our 36 anti-Ro (SSA) positive and the rest of our SLE patients. However, the coexistence of anti-Ro (SSA) and anti-La (SSB) antibodies (9 patients) correlated significantly with HLA-B8, whereas the haplotype HLA-B8DR3 was more common in the anti-Ro (SSA) positive patients than in the rest-although the difference did not reach statistical significance. The combination of high anti-ds-DNA and low C4 serum levels correlated with absence of HLA-DR5. Our findings, while in agreement with those of certain previous studies, are somewhat different from those of others. The differences may at least partly be related to variations in the control populations employed. On the other hand some of the differences, in accordance with other peculiarities of Greeks with connective tissue disease, emphasize the role of racial and/or ethnic background in the HLA-association of various autoimmune diseases and the fact that the detectable HLA alloantigens in certain diseases modify disease and autoantibody expression rather than being responsible for the autoimmune process itself.     

Autoantibodies associated with RNA are more enriched than anti-dsDNA antibodies in circulating immune complexes in SLE

To what extent different autoantibodies accumulate in systemic lupus erythematosus (SLE) immune complexes (ICs), and whether such accumulation is associated with disease activity has been investigated. ICs were isolated from SLE sera by both polyethylene glycol (PEG) precipitation and C1q-binding. Autoantibody specificities were determined using a lineblot assay quantified by densitometry. To compare the relative levels of autoantibodies, levels were normalized to the total levels of IgG measured by ELISA in sera and parallel ICs. Samples were investigated both in a cross-sectional design as well as in a paired design with samples obtained during both active and inactive SLE. All investigated autoantibody specificities except anti-dsDNA were enriched in circulating ICs as compared with parallel sera. The group of antibodies against RNA-associated antigens (anti-RNP/Sm, anti-Sm, anti-SSA/Ro60, anti-SSA/Ro52, anti-SSB/La) all exhibited higher median enrichment than the DNA-associated (anti-dsDNA, anti-histones, anti-nucleosomes) or cytoplasmic (anti-ribosomal P) antigens. In particular autoantibodies against RNP/Sm and SSA/Ro52 had the highest degree of enrichment in SLE PEG precipitates. These findings were corroborated by analysis of autoantibody content in C1q-bound ICs. There was no difference in degree of IC accumulation of the investigated autoantibodies during active and inactive SLE. Our findings demonstrate a difference in enrichment between autoantibodies against RNA- and DNA-associated autoantigens in isolated SLE IC, suggesting that the RNA-associated autoantibodies are more prone to form circulating ICs in SLE, in contrast to antibodies against DNA-associated autoantigens such as dsDNA. These finding have implications in understanding mechanisms of differential autoantibody accumulation in target organs in SLE.     

抗原处理相关转运体基因与系统性红斑狼疮及自身抗体的相关性

目的 探讨皖籍汉族人群抗原处理相关转运体(transporter associated with antigen processing,TAP)基因与系统性红斑狼疮(systemic lupus erythematosus,SLE)及自身抗体的相关性。方法 应用聚合酶链反应—序列特异性寡核苷酸探针杂交(PCR—SSO))技术对80例SLE患者及96名正常对照人群进行TAP1、TAP2等位基因分型，按实验室常规检测ANA、抗dsDNA、抗RNP、抗Sm、抗SSA、抗SSB抗体。结果 本研究人群的TAP1和TAP2各有4种等位基因型，其频率依次为TAP1*0101＞*020l＞*0301＞*0401，TAP2*0101＞*0201＞*0102＞*0202，有6．8％(12／176)的研究对象用TAPl探针无法定型，10．2％(18／176)TAP2无法定型，呈杂交空白。SLE患者与正常对照人群间TAP等位基因型分布差异无显著性(P＞0．05)。抗RNP抗体与TAP1*0401呈正相关，抗dsDNA及抗SSA抗体与TAP2*0201呈正相关(P＜0．05)。结论 末证明TAP等位基因与SLE的相关性。TAP等位基因与自身抗体的相关性可能和TAP与HLA基因存在连锁不平衡现象有关。     

Elevated levels of TRAIL in systemic lupus erythematosus are associated to the presence of anti-SSA/SSB antibodies

The objective of this study was to determine potential relationship between the levels of serum TNF-related apoptosis inducing ligand (TRAIL) and osteoprotegerin (OPG) and clinical markers in systemic lupus erythematosus (SLE) patients. Forty SLE patients with inactive disease were enrolled in this study. For comparison, 20 Sj?gren's syndrome (SS) patients and 30 normal controls were also analysed. Serum levels of TRAIL and OPG were determined by ELISA. Serum TRAIL and OPG concentrations in SLE patients were significantly (P < 0.05) higher than those in healthy volunteers. Of note, serum TRAIL but not OPG was significantly (P < 0.05) higher in the SLE patient subset characterized by the presence of anti-SSA/SSB antibodies. The relationship between high levels of TRAIL and SSA/SSB antibodies was further supported by the analysis of SS patients characterized by SSA/SSB antibodies positivity, in which TRAIL levels resulted comparable to the subgroup of anti-SSA/SSB positive SLE patients. The presence of SSA/SSB antibodies, targeting a specific subset of SLE and SS patients, is related to increased serum levels of TRAIL but not of OPG.     

ANTI La(SSB) IDENTIFIES A DISTINCTIVE SUBGROUP OF SYSTEMIC LUPUS ERYTHEMATOSUS

The relevance of antibodies for La(SSB) as a marker of a distinctivesystemic lupus erythematosus (SLE) subset was studied in 185lupus patients. Anti La was detected in 39 (21%) and was accompaniedinvariably by anti Ro. Clinically, anti La-positive patientswere distinguished by a later age of disease onset, and a lowfrequency of lupus nephritis. In common with other anti Ro-positivepatients they showed a high frequency of keratoconjunctivitissicca. Anti La identified patients with higher titres of antiRo antibodies and was significantly associated with HLA-DR3.Serological markers such as these are useful for identifyingmore homogeneous populations of SLE patients for studies ofaetiology and pathogenesis. KEY WORDS: SLE, anti La(SSB), anti Ro(SSA), Elderly lupus     

Differential expression of Ro/SSA 60 kDa and La/SSB, but not Ro/SSA 52 kDa, mRNA and protein in minor salivary glands from patients with primary Sjögren's syndrome

OBJECTIVE: To analyze the protein and messenger RNA (mRNA) expression of La/SSB, Ro/SSA 60, and Ro/SSA 52 antigens in minor salivary glands (MSG) from patients with primary Sj?gren's syndrome (pSS). METHODS: La/SSB, Ro/SSA 60, and Ro/SSA 52 protein expression was studied by immunohistochemistry in MSG from 26 patients with pSS and 16 controls. mRNA expression was determined by real-time polymerase chain reaction in MSG of 10 patients with pSS and 7 controls. RESULTS: La/SSB and Ro/SSA 60, but not Ro/SSA 52, mRNA expression was higher in samples from patients with pSS compared to controls (p < 0.05). La/SSB protein had higher expression in the cytoplasm of ductal cells than in the cytoplasm of mucous acinar cells in patients with pSS (p = 0.013) but not in controls. Ro/SSA 60 had higher expression in the cytoplasm of ductal cells than in the cytoplasm of serous acinar cells in patients with pSS (p = 0.006) but not in controls. The Ro/SSA 52 expression pattern was similar in patients and controls. There was no association between circulating autoantibodies to Ro/SSA or La/SSB and the aberrant expression of the cognate autoantigens. CONCLUSION: The increased Ro/SSA 60 and La/SSB mRNA expression in MSG of patients with pSS as well as the differential Ro/SSA 60 and La/SSB protein expression in ductal cells of MSG in patients with pSS suggest that these these 2 autoantigens, but not Ro/SSA 52, are probably involved in triggering and maintaining the tissue-specific autoimmune response in pSS MSG and may contribute to the antigen-driven immune response and local autoantibody production in pSS.     

HLA markers and clinical characteristics in Caucasians with primary Sjögren's syndrome

OBJECTIVE: To explore the association between HLA genotypes and clinical and immunological characteristics in Caucasians with primary Sj?gren's syndrome (pSS). METHODS: HLA genotyping for DRB1, DQA1 and DQB1 was carried out in 62 single case patients with pSS and 64 healthy controls. The specific amino acid residues at DQA1 position 34 (DQalpha-34Q) and DQB1 position 26 (DQbeta-26L) in addition to the DQ-DI (AA59-AA69) motif were deterrmined. Subsequently, the relative contribution of individual HLA markers to clinical and immunologic characteristics of pSS was assessed by group comparisons. RESULTS: No significant associations were seen between HLA markers and histopathological or clinical features of pSS. Significant positive associations with HLA Class II markers were restricted to the formation of different autoantibodies. Formation of an anti-Ro/SSA and anti-La/SSB autoantibody response was positively associated with DRB1*03, DQB1*02 and DRB1*03/DRB1*15-DQB1*02/DQB1*0602 heterozygosity. Patients positive for anti-La/SSB also showed a strong positive anti-La/SSB association with DQA1*0501. Considering the contribution of individual DQA1 and DQB1 amino acids and sequence motifs to the formation of anti-Ro/SSA and anti-La/SSB autoantibodies, a dose dependent positive influence was detected for DQalpha-34Q and DQbeta-26L. For DQbeta-DI, the largest difference between patients and controls was seen for the presence of a single copy of this motif after selecting patients with either anti-Ro/SSA or anti-La/SSB autoantibodies. CONCLUSION: The association of HLA Class II markers with pSS may concern the anti-Ro/La response rather than the disease itself. The strongest contributors to the formation of an anti-Ro/La response included components of the DRB1*03-DQB1*02-DQA1*0501 haplotype also encompassing the transethnically-associated DQbeta-DI motif. In addition, the dose dependent contribution of DQalpha-34Q and DQbeta-26L argue for a recessive contribution of HLA-DQ to the formation of an anti-Ro/La response. Given the prominent associations with DRB1*03 and the complex dose dependent interactions at HLA-DQ, a joint contribution of HLA-DR and DQ is likely to be relevant for the formation of anti-Ro/La autoantibodies in patients with pSS.     

Autoimmune response in mothers of children with congenital and postnatally diagnosed isolated heart block: a population based study

OBJECTIVE: To study the autoimmune response in mothers of children with isolated congenital heart block (CHB) and heart block (HB) diagnosed postnatally. METHODS: We reviewed the Finnish hospital registries for patients born between 1950 and 2000 and diagnosed with isolated HB before the age of 16 years. Clinical data and sera for the determination of autoantibodies were available from 67 mothers of children with CHB and from 37 mothers of children with postnatally diagnosed HB 9.9 years and 22.6 years (mean) after the index delivery, respectively. Maternal antibodies to 52 kDa and 60 kDa SSA and 48 kDa SSB were determined by time-resolved fluoroimmunoassay (TR-FIA) and by immunoblotting. Other marker antibodies for connective tissue diseases (CTD) were determined by immunoblot and/or by immunofluorescence. The control group comprised 136 mothers with primary Sj?gren's syndrome (SS), systemic lupus erythematosus (SLE), or other CTD with healthy children. RESULTS: Sixty of our 67 mothers (90%) of children with CHB had antibodies to SSA or SSB by the methods initially used in this study. When retests and tests performed previously were taken into account, only 3 (4%) of the 67 mothers did not have any autoantibodies. Two (3%) of the 67 mothers had antibodies to dsDNA and one (1%) each to Jo-1/HRS, RNP-70 kDa, and histone proteins. Of 37 mothers of children with postnatally diagnosed HB, only 3 (8%) had any autoantibodies. Increased risk of having a child with CHB was indicated by maternal primary SS and high levels of anti-SSA and anti-SSB by all assays, whereas low risk was indicated by maternal SLE or other CTD and undetectable or low levels of the antibodies. No single anti-SSA or anti-SSB test was clearly superior to others, but in general, immunoblots were more specific than TR-FIA. CONCLUSION: Maternal autoimmune disorder is almost always associated with CHB but only rarely with postnatally diagnosed HB. Anti-SSA and anti-SSB are marker antibodies for mothers of children with CHB, and an increased risk of having an affected child is indicated by maternal primary SS and high titer antibodies to SSA and SSB.     

Anti-SSA/Ro and anti-SSB/La antibodies. What's new?

Anti-SSA/Ro and anti-SSB/La autoantibodies recognize different epitopes on polypeptides associated with small RNAs called scYRNA situated mostly in the cytoplasmic compartment (70%) and few in the nuclear compartment (30%). These hYRNPs (h=human) can be found on the cytoplasmic membrane or in small blebs during apoptosis after various stimuli such as UVB, 17-beta-estradiol, viral infection, TNF alpha and other cellular apoptosis inducing molecules. At least two major different proteins are called SSA/Ro: a 52 kDa Ro (with two subtypes alpha and beta) and a 60 kDa Ro. There is only one SSB/La protein of 48 kDa. In some circumstances, other proteins such as calreticuline (MW 57 kDa) join Ro/SSA proteins on some YRNAs. Anti-SSA/Ro antibodies are detected in the sera of 30% of patients with SLE, even during preclinical setting; anti-Ro/SSA are strongly associated (90%) with some subtypes of SLE such as old-onset (>50 y) SLE, subacute lupus erythematosus, drug-induced subacute lupus erythematosus and in patients with hereditary C2 or C4 or C1q deficiency with lupus or lupus-like disease. Anti-SSA/Ro are also associated with primary Sj?gren syndrome (50% to 60%) and with undifferenciated connective tissue disease (UCTD). Anti-SSA/Ro antibodies are almost always present in sera of mothers with babies with neonatal lupus syndrome (NNL) and with complete congenital heart block (CCHB). This last event is very unusual in pregnant patients with anti-Ro/SSA antibodies (1% to 2% of primigeste women). Some good evidences such as experimental models in vitro or ex-vivo, argue for the responsibility of maternal anti-Ro/SSA 52 kDa and/or anti-La/SSB antibodies (or associated IgG antibodies) as major etiologic factor of CCHB and NNL. IgG anti-Ro 52 beta kDa has been shown able to interrupt the atrioventricular conduction as well as the L calcium channel influx of fetal cardiocytes. Other factors must be taken into account to explain discordant twins (with and without CCHB). More recently anti-Ro/SSA antibodies were associated with QT interval prolongation in newborns without CCHB.     

Clinical, immunological, and immunogenetic aspects of autoantibody production against Ro/SSA, La/SSB and their linear epitopes in primary Sjögren's syndrome (pSS): a European multicentre study

Objectives: To investigate the clinical and immunogenetic aspects of antibody formation against Ro/SSA and La/SSB as well as their linear B cell epitopes in patients with primary Sjögren''s syndrome (pSS) from different European countries. Patients and methods: Ninety patients with pSS from six European centres were studied. Serum samples from all patients were tested in a control laboratory for anti-Ro/SSA and anti-La/SSB autoantibodies by RNA precipitation assay and autoantibodies to the previously reported B cell linear epitopes of Ro 60 kDa (p169–190aa and p211–232aa) and La/SSB (p147–154aa, p291–302aa, p301–318aa, and p349–364aa). DNA from 88 patients was used for the determination of HLA-DRB1, -DQA1, and -DQB1 genotypes. Analysis of the results was performed in the 88 patients who were genotyped and tested also for antipeptide antibodies. Results: Antibodies to B cell epitopes of Ro 60 kDa were detected at a low frequency (range 10–37%). In contrast, B cell epitopes of La/SSB were detected frequently (range 58–86%) among the anti-La/SSB positive sera. Autoantibodies to the La/SSB epitope, p349–364aa, were significantly positively associated with longer disease duration (p<0.05), recurrent or permanent parotid gland enlargement (p<0.005), and a higher proportion of non-exocrine manifestations (p<0.005), compared with patients without autoantibodies. The presence of anti-Ro/SSA and anti-La/SSB autoantibodies was significantly associated with the presence of HLA-DRB1*03 and DQB1*02 (p=0.038 and p=0.034, respectively). This association was even more prominent and extended to HLA-DQA1*0501 when patients were stratified according the presence of autoantibodies to discrete La/SSB B cell epitopes in comparison with autoantibody negative patients (p<0.01). They were found also to be highly associated with the alleles HLA-DQB1*02 and HLA-DQA1*0501 as well as the presence of a shared amino acid motif in the region 59–69aa of DQB1 first domain (p<0.01, respectively). Conclusions: Autoantibodies against La/SSB, binding to four synthetic peptides, derived from the sequence of the La protein were identified with increased frequency in sera of patients with pSS. The formation of autoantibodies against B cell epitope analogues of La/SSB in European patients with pSS may be dependent on the presence of a permissive HLA-DQ heterodimer, most prominently represented by the HLA-DQA1*0501/DQB1*0201 heterodimer, suggesting that a model of HLA restricted presentation of La/SSB peptide determinants is crucial for the autoimmune response against La/SSB.