A B cell apotope of Ro 60 in systemic lupus erythematosus

OBJECTIVE: Previous studies have attempted to segregate anti-60-kd Ro/SSA (anti-Ro 60) responses in systemic lupus erythematosus (SLE) and primary Sj?gren's syndrome (SS) but have shown limited disease preference. The aim of the present study was to determine whether the presence of autoantibodies against an Ro 60 apotope (an epitope expressed on apoptotic cells) distinguishes anti-Ro 60 responses in SLE and primary SS. METHODS: Multiparameter flow cytometry was used to select early apoptotic cells and measure the simultaneous binding of annexin V, propidium iodide, and anti-Ro 60-positive IgG from SLE patients (n=21) and patients with primary SS (n=19). The specificity of the Ro 60 apotope was determined by inhibition experiments with recombinant and native Ro 60. RESULTS: Autoantibodies against the Ro 60 apotope were prevalent in SLE patients (13 of 21, 62%) and were rarely observed in patients with primary SS (1 of 19, 5%) (P=0.0002). Further, within SLE patients, autoantibodies to the Ro 60 apotope strongly distinguished patients with anti-Ro 60 alone (12 of 13, 92%) from those with both anti-Ro 60 and anti-La (1 of 8, 13%) (P=0.0005). When we considered all patients with anti-Ro 60 alone, the presence of autoantibodies to the Ro 60 apotope had both high sensitivity (92.3%) and high specificity (85.7%) for SLE compared with primary SS (P=0.0012). The presence of autoantibodies to the Ro 60 apotope may therefore be of diagnostic value in patients with isolated anti-Ro 60 responses. CONCLUSION: The preferential targeting of an Ro 60 apotope exposed on early apoptotic cells in a subset of SLE patients implies disease-specific pathways for the induction of anti-Ro 60 autoimmunity.     

ANA negative systemic lupus erythematosus sera revisited serologically

OBJECTIVE: To better define the serology of a panel of sera from patients with a clinical diagnosis of systemic lupus erythematosus (SLE) or subacute cutaneous lupus erythematosus (SCLE) with a negative antinuclear antibody (ANA) test on mouse liver. METHODS: Sensitive ELISA methods for anti-Ro/SSA, anti-La/SSB, and anti-U1RNP were applied to a panel of 76 sera with either SLE or SCLE and a negative ANA test on mouse liver. RESULTS: These sera had previously been shown to have a high prevalence of anti-Ro/SSA (68%) and anti-La/SSB (27%) precipitins respectively. None had precipitins to U1RNP or Sm. ELISA methodology revealed that all of the sera 76/76 (100%) had elevated levels (> mean +/- 2 SD of a panel of 21 normal sera) of anti-Ro/SSA, 36/76 (46%) had elevated levels of anti-La/SSB, and 27 of 76 (35%) had elevated levels of anti-U1RNP. CONCLUSION: The subset of patients with SLE and SCLE with a negative ANA test on mouse liver almost uniformly have antibodies to the Ro/SSA antigen by a sensitive ELISA. This adds evidence to the idea that this is a more homogeneous disease subset within the spectrum of SLE.     

Chilblain lupus erythematosus is associated with antibodies to SSA/Ro.

Chilblain lupus erythematosus (CL) of Hutchinson is a subtype of lupus erythematosus (LE) characterized by erythematous lesions induced by cold, damp climates. A number of patients affected by CL eventually develop features of systemic lupus erythematosus (SLE). We report here 9 patients with chilblain cutaneous lesions, 6 of them were affected by SLE and 2 by SCLE. The onset of CL preceded the diagnosis of LE, from 1 to 10 years in 3 cases, it was concurrent in one case and was subsequent in the remaining 4 cases. Raynaud's phenomenon and photosensitivity were other prominent clinical features in patients with CL. Nailfold capillaroscopy revealed pathological changes in every patient examined. ANA and anti-SSA/Ro antibodies were detected in all nine patients. Anti-SSB/La were detected in 2 cases, anti-Sm in one case, and anti-Sm and anti-RNP in a one case. Antibodies to dsDNA and complement consumption were found in the six patients with SLE. The fine specificity of anti-SSA/Ro was determined by immunoblotting: anti-60kD and anti-52 kD were detected in three sera, anti-60kD alone in 5 sera, while one serum did not blot. In conclusion, the present study suggests that chilblain LE is associated with SSA/Ro autoantibodies, as is SCLE, hypergammaglobulinemic purpura and neonatal lupus erythematosus.     

Serial analysis of Ro/SSA and La/SSB antibody levels and correlation with clinical disease activity in patients with systemic lupus erythematosus

OBJECTIVE: To investigate the temporal correlation between anti-Ro/SSA and anti-La/SSB antibody levels and compare them with variation in clinical disease activity in patients with systemic lupus erythematosus (SLE). METHODS: Sequential serum samples collected over 18-44 months from 18 anti-Ro/SSA positive patients with systemic lupus erythematosus were analysed by ELISA with recombinant Ro60, Ro52 and La antigens. Disease activity was assessed by the BILAG index. RESULTS: Limited antibody level variation over time was found in most patients, but a subset displayed more changes and a co-variation between the levels of separate specificities was found in 40% of patients. In two patients antibody levels fluctuated with the global score. Antibodies also correlated with separate organ/systems involvement in individual patients. CONCLUSION: The Ro60, Ro52 and La antibody profile is fixed at an early stage of disease and in most patients hardly changes. Patients with fluctuating levels tend to have a co-ordinated expression of these autoantibodies.     

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.     

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.     

HLA-DR antigens in systemic lupus erythematosus: association with specificity of autoantibody responses to nuclear antigens.

HLA-DR antigens and autoantibodies to the nuclear or cytoplasmic antigens Ro/SSA, La/SSB, Sm, and RNP were determined in North American and Austrian patients with systemic lupus erythematosus (SLE). Analysis of the association of antibodies to these ribonucleic acid (RNA)-protein antigens with HLA-DR antigens showed that HLA-DR3 was related to the presence of anti-Ro/SSA or anti-La/SSB, or both. In contrast, anti-Sm or anti-RNP, or both were associated with HLA-DR4. HLA-DR5 was associated with absence of these autoantibodies. The data extend evidence for the complexity and heterogeneity of SLE. Moreover, they indicate that, in SLE, genes linked to those coding for HLA-DR antigens, are related to the specificity of autoantibody responses rather than to the primary immunological abnormalities of this disorder.     

The intracellular 52-kd Ro/SSA autoantigen in keratinocytes is up-regulated by tumor necrosis factor alpha via tumor necrosis factor receptor I

OBJECTIVE: Previous studies have shown that the nuclear Ro/SSA autoantigens involved in photosensitive cutaneous lupus manifestations are regulated by ultraviolet B (UVB) irradiation. UVB exposure triggers the release of tumor necrosis factor alpha (TNFalpha) from keratinocytes in the epidermis and from mast cells in the dermis. The present study aimed to characterize the effect of TNFalpha on messenger RNA (mRNA) and protein expression of the intracellular 52-kd Ro/SSA autoantigen in primary human keratinocytes and to elucidate the TNFalpha receptor (TNFR) signaling pathways mediating this effect. METHODS: Expression of 52-kd Ro/SSA mRNA in primary human keratinocytes was investigated by quantitative real-time polymerase chain reaction (LightCycler system) using GAPDH as the housekeeping gene. Expression of 52-kd Ro/SSA protein was studied by flow cytometry after staining intracellular protein with IgG purified from an anti-52-kd Ro/SSA-positive serum. TNFR function was assessed by culturing cells in the presence and absence of neutralizing antibodies directed against the TNFR subunits TNFRI and TNFRII. RESULTS: TNFalpha-induced up-regulation of 52-kd Ro/SSA mRNA expression peaked at 4 hours, followed by up-regulation of intracellular 52-kd Ro/SSA protein expression at 24 hours, independently of apoptosis. Between different donors, a high variability of both constitutive expression levels and TNFalpha-induced changes in 52-kd Ro/SSA mRNA and protein expression was observed. The up-regulatory effect of TNFalpha on 52-kd Ro/SSA mRNA and protein expression was inhibited by anti-TNFRI antibodies but enhanced by anti-TNFRII antibodies. CONCLUSION: The finding that TNFalpha up-regulates 52-kd Ro/SSA expression in keratinocytes via TNFRI suggests that it may play a role in the pathogenesis of anti-Ro/SSA-associated cutaneous lupus erythematosus.     

Can B cell epitopes of 60 kDa Ro distinguish systemic lupus erythematosus from Sj?gren's syndrome?

Antibodies binding components of the Ro/La (or SSA/SSB) ribonucleoprotein particle are found in the sera of patients with systemic lupus erythematosus (SLE) and Sj?gren's syndrome (SS) as well as mothers who give birth to babies with neonatal lupus. Anti-La occurs in a subset of sera that contain anti-Ro, and anti-La is found more commonly in sera of patients with SS than in sera from SLE patients. The fine specificity of autoantibodies binding 60 kDa has been studied extensively. Recent data have suggested that there are disease-specific epitopes which identify patients with either SLE or SS. Alternatively, other data suggest that the B cell epitopes of 60kDa Ro vary according to the presence of anti-La. The present study was undertaken to determine whether binding of putative disease-specific 60 kDa Ro epitopes is associated with the diagnosis of SLE vs SS, or instead associated with the presence of anti-La. Anti-60 kDa Ro positive sera from 24 SLE patients and 44 SS patients were studied for antibodies binding two epitopes of 60 kDa Ro. We find the epitope defined by residues 171-190 is associated with anti-60 kDa Ro without anti-La, regardless of diagnosis. Meanwhile, binding of the epitope defined by residues 215-232 is not commonly found in anti-60 kDa Ro sera, especially in those sera with both anti-60 kDa Ro and anti-La. Thus, the fine specificity of antibody binding to 60 kDa Ro varies according to the presence of anti-La, not to the diagnosis of either SLE or SS.     

The intracellular 52‐kd Ro/SSA autoantigen in keratinocytes is up‐regulated by tumor necrosis factor α via tumor necrosis factor receptor I

Objective

Previous studies have shown that the nuclear Ro/SSA autoantigens involved in photosensitive cutaneous lupus manifestations are regulated by ultraviolet B (UVB) irradiation. UVB exposure triggers the release of tumor necrosis factor α (TNFα) from keratinocytes in the epidermis and from mast cells in the dermis. The present study aimed to characterize the effect of TNFα on messenger RNA (mRNA) and protein expression of the intracellular 52‐kd Ro/SSA autoantigen in primary human keratinocytes and to elucidate the TNFα receptor (TNFR) signaling pathways mediating this effect.

Methods

Expression of 52‐kd Ro/SSA mRNA in primary human keratinocytes was investigated by quantitative real‐time polymerase chain reaction (LightCycler system) using GAPDH as the housekeeping gene. Expression of 52‐kd Ro/SSA protein was studied by flow cytometry after staining intracellular protein with IgG purified from an anti–52‐kd Ro/SSA–positive serum. TNFR function was assessed by culturing cells in the presence and absence of neutralizing antibodies directed against the TNFR subunits TNFRI and TNFRII.

Results

TNFα‐induced up‐regulation of 52‐kd Ro/SSA mRNA expression peaked at 4 hours, followed by up‐regulation of intracellular 52‐kd Ro/SSA protein expression at 24 hours, independently of apoptosis. Between different donors, a high variability of both constitutive expression levels and TNFα‐induced changes in 52‐kd Ro/SSA mRNA and protein expression was observed. The up‐regulatory effect of TNFα on 52‐kd Ro/SSA mRNA and protein expression was inhibited by anti‐TNFRI antibodies but enhanced by anti‐TNFRII antibodies.

Conclusion

The finding that TNFα up‐regulates 52‐kd Ro/SSA expression in keratinocytes via TNFRI suggests that it may play a role in the pathogenesis of anti‐Ro/SSA–associated cutaneous lupus erythematosus.

     

Clinical features of Sjögren’s syndrome associated with recurrent annular erythema

Our objective was to describe the clinical features of Sjögren’s syndrome (SS) with recurrent annular erythema which resembles subacute cutaneous lupus erythematosus (SCLE), and determine a possible association of anti-SS-A/Ro and/or SS-B/La antibody titers with the episodes of cutaneous manifestation. Recurrent annular erythema was observed in 4% (six patients; five females and one male) of our 143 patients diagnosed as primary SS. All the patients developed annular erythema on the facial area as their initial manifestation when they were between 21 and 31 years old. They had few subjective sicca symptoms, but both anti-SS-A/Ro and SS-B/La antibodies were positive and parotid sialography showed typical findings for SS (subclinical SS). Parotid gland swellings had developed in five of the patients during their follow-up periods, (3–12 years). In addition to the facial area, most patients repeated the cutaneous episodes on extremities and palmar, plantar or auricular areas. Skin biopsy was performed in three patients and the common findings were mononuclear cell infiltrations in the dermis with few epidermal changes. Transient leukopenia (four patients), low titers of anti-DNA antibodies (one patient) and chronic false-positive results of serological tests for syphilis (one patient) were observed. Two of our patients, therefore, temporarily fulfilled four items of the ARA classification criteria for systemic lupus erythematosus (SLE), if their facial erythema was considered as malar rash. Serum antibodies to 52 kDa SS-A/Ro peptides (80%) were more frequently detected in the five patients examined by enzyme-linked immunosorbent assays (ELISA), compared with those to 60 kDa SS-A/Ro peptides (40%). Furthermore, we could serially determine serum anti-SS-A/Ro and SS-B/La antibody titers in three patients by using ELISA for 3 or 4 years. Annular erythema usually developed when the antibody titers became relatively high and disappeared after the treatment with oral prednisolone which suppressed the antibody titers. We could observe five pregnancies in our three patients and all the patients developed annular erythema during their pregnant periods. Their five infants, however, were free from any complications such as neonatal lupus erythematosus and congenital heart block. We conclude that annular erythema is a rare manifestation of SS and develops in relatively young patients who are subclinical for sicca symptoms. The cutaneous episodes seemed to relate with anti-SS-A/Ro and/or SS-B/La antibody titers. Some of the erythema observed in SS patients may belong to SCLE, but they do not usually develop typical SLE. The possibility that SS may be more frequent in the SCLE patients remains to be determined.     

A serology-based approach combined with clinical examination of 125 Ro/SSA-positive patients to define incidence and prevalence of subacute cutaneous lupus erythematosus

OBJECTIVE: To estimate the incidence and prevalence of Ro/SSA-positive subacute cutaneous lupus erythematosus (SCLE) in Stockholm County, Sweden (1.8 million inhabitants) and to investigate the frequency of photosensitivity and other clinical manifestations associated with Ro/SSA autoantibodies. METHODS: Ro/SSA-positive patients in Stockholm were identified via registry-based searches. All patients who tested positive for the presence of Ro/SSA autoantibodies during 1996-2002 (n = 1,323; 85% women) were identified. A questionnaire was sent to all patients still living in Stockholm in 2003 (n = 1,048). Patients who reported having skin symptoms and photosensitivity (n = 125) underwent a clinical examination. RESULTS: Of the 741 (71%) of 1,048 Ro/SSA-positive patients who responded to the questionnaire, 400 (54%) reported having photosensitivity, and of these patients, 125 agreed to be clinically examined. A diagnosis of LE was confirmed in 59 of the 125 patients (SCLE in 20, systemic LE [SLE] in 33, and chronic CLE in 6). Eighty-six patients reported experiencing symptoms consistent with polymorphous light eruption (PLE). Comorbidities such as cardiovascular disease, autoimmune disease, and other skin diseases were common. The incidence of Ro/SSA-positive SCLE during the study period was estimated to be 0.7 cases per 100,000 persons per year and the prevalence was approximately 6.2-14 in 100,000 persons. CONCLUSION: The incidence of Ro/SSA-positive SCLE in Stockholm County, Sweden is estimated to be 0.7 per 100,000 persons per year as compared with an incidence of SLE in Sweden of 4.8 per 100,000 persons per year. The prevalence is estimated to be 6.2-14 in 100,000 persons. Self-reported photosensitivity commonly corresponds to a history of PLE in Ro/SSA-positive patients, even when the clinical profile of SCLE is absent. Photoprotection should therefore be included in the treatment recommendations for these patients.     

Clinical features of Sjögren’s syndrome associated with recurrent annular erythema

Abstract

Our objective was to describe the clinical features of Sjögren’s syndrome (SS) with recurrent annular erythema which resembles subacute cutaneous lupus erythematosus (SCLE), and determine a possible association of anti-SS-A/Ro and/or SS-B/La antibody titers with the episodes of cutaneous manifestation. Recurrent annular erythema was observed in 4% (six patients; five females and one male) of our 143 patients diagnosed as primary SS. All the patients developed annular erythema on the facial area as their initial manifestation when they were between 21 and 31 years old. They had few subjective sicca symptoms, but both anti-SS-A/Ro and SS-B/La antibodies were positive and parotid sialography showed typical findings for SS (subclinical SS). Parotid gland swellings had developed in five of the patients during their follow-up periods, (3–12 years). In addition to the facial area, most patients repeated the cutaneous episodes on extremities and palmar, plantar or auricular areas. Skin biopsy was performed in three patients and the common findings were mononuclear cell infiltrations in the dermis with few epidermal changes. Transient leukopenia (four patients), low titers of anti-DNA antibodies (one patient) and chronic false-positive results of serological tests for syphilis (one patient) were observed. Two of our patients, therefore, temporarily fulfilled four items of the ARA classification criteria for systemic lupus erythematosus (SLE), if their facial erythema was considered as malar rash. Serum antibodies to 52 kDa SS-A/Ro peptides (80%) were more frequently detected in the five patients examined by enzyme-linked immunosorbent assays (ELISA), compared with those to 60 kDa SS-A/Ro peptides (40%). Furthermore, we could serially determine serum anti-SS-A/Ro and SS-B/La antibody titers in three patients by using ELISA for 3 or 4 years. Annular erythema usually developed when the antibody titers became relatively high and disappeared after the treatment with oral prednisolone which suppressed the antibody titers. We could observe five pregnancies in our three patients and all the patients developed annular erythema during their pregnant periods. Their five infants, however, were free from any complications such as neonatal lupus erythematosus and congenital heart block. We conclude that annular erythema is a rare manifestation of SS and develops in relatively young patients who are subclinical for sicca symptoms. The cutaneous episodes seemed to relate with anti-SS-A/Ro and/or SS-B/La antibody titers. Some of the erythema observed in SS patients may belong to SCLE, but they do not usually develop typical SLE. The possibility that SS may be more frequent in the SCLE patients remains to be determined.     

A serology‐based approach combined with clinical examination of 125 Ro/SSA‐positive patients to define incidence and prevalence of subacute cutaneous lupus erythematosus

Objective

To estimate the incidence and prevalence of Ro/SSA‐positive subacute cutaneous lupus erythematosus (SCLE) in Stockholm County, Sweden (1.8 million inhabitants) and to investigate the frequency of photosensitivity and other clinical manifestations associated with Ro/SSA autoantibodies.

Methods

Ro/SSA‐positive patients in Stockholm were identified via registry‐based searches. All patients who tested positive for the presence of Ro/SSA autoantibodies during 1996–2002 (n = 1,323; 85% women) were identified. A questionnaire was sent to all patients still living in Stockholm in 2003 (n = 1,048). Patients who reported having skin symptoms and photosensitivity (n = 125) underwent a clinical examination.

Results

Of the 741 (71%) of 1,048 Ro/SSA‐positive patients who responded to the questionnaire, 400 (54%) reported having photosensitivity, and of these patients, 125 agreed to be clinically examined. A diagnosis of LE was confirmed in 59 of the 125 patients (SCLE in 20, systemic LE [SLE] in 33, and chronic CLE in 6). Eighty‐six patients reported experiencing symptoms consistent with polymorphous light eruption (PLE). Comorbidities such as cardiovascular disease, autoimmune disease, and other skin diseases were common. The incidence of Ro/SSA‐positive SCLE during the study period was estimated to be 0.7 cases per 100,000 persons per year and the prevalence was ∼6.2–14 in 100,000 persons.

Conclusion

The incidence of Ro/SSA‐positive SCLE in Stockholm County, Sweden is estimated to be 0.7 per 100,000 persons per year as compared with an incidence of SLE in Sweden of 4.8 per 100,000 persons per year. The prevalence is estimated to be 6.2–14 in 100,000 persons. Self‐reported photosensitivity commonly corresponds to a history of PLE in Ro/SSA‐positive patients, even when the clinical profile of SCLE is absent. Photoprotection should therefore be included in the treatment recommendations for these patients.

     

Antibodies to Ro and La

Precipitating antibodies to Ro and La occur in a subset of patients with systemic lupus erythematosus (SLE) constituting just under 50 and 20% respectively of the total spectrum. These precipitating autoantibodies are even more prevalent in primary Sj?gren's syndrome (SS) occurring in 60-80% (anti-Ro) and 40-60% (anti-La) of that disease. Patients with an overlap of SLE and SS virtually all possess both anti-Ro and anti-La. These autoantibodies appear years before the appearance of clinical disease as evidenced by the behavior of women who possess them and herald this presence by having children born with the manifestations of neonatal lupus, principally a characteristic lupus dermatitis or complete congenital heart block. The close association of several clinical manifestations involving the skin, lung, and blood elements suggests a pathogenic role for these autoantibodies in disease expression. The elucidation of these relationships should greatly improve our understanding of the etiopathogenesis of both SLE and SS.     

Low titer,isolated anti Ro/SSA 60 kd antibodies is correlated with positive pregnancy outcomes in women at risk of congenital heart block

Clinical Rheumatology - Congenital heart block (CHB) is an autoantibody mediated disorder presumably caused by placental transmission of maternal autoantibodies to Ro/SSA 52 kd, p200, Ro/SSA 60 kd,...     

Serum type I interferon activity is dependent on maternal diagnosis in anti-SSA/Ro-positive mothers of children with neonatal lupus

OBJECTIVE: The type I interferon (IFN) pathway is activated in many patients with systemic lupus erythematosus (SLE), and high serum levels of IFN are associated with anti-SSA/Ro autoantibodies. To investigate the clinical features associated with type I IFN production in vivo, we compared serum IFN activity in individuals with anti-SSA/Ro antibodies who were asymptomatic with that in individuals with clinical manifestations of SLE or Sj?gren's syndrome (SS). METHODS: Antibody-positive sera from 84 mothers of children with manifestations of neonatal lupus were studied for type I IFN activity, using a functional reporter cell assay. Maternal health status was characterized as asymptomatic, SS, SLE, pauci-SLE, or pauci-SS, based on a screening questionnaire, telephone interview, and review of medical records. The prefix "pauci-" indicates symptoms insufficient for a formal classification of the disease. RESULTS: Only 4% of asymptomatic mothers had high serum type I IFN activity, compared with 73% with pauci-SLE (P = 5.7 x 10(-5)), 35% with SLE (P = 0.011), and 32% of patients with SS (P = 0.032). One of the 4 patients with pauci-SS had high levels of IFN. The majority of patients for whom longitudinal data were available had stable type I IFN activity over time, and changes in IFN activity were not clearly accompanied by changes in the clinical diagnosis. CONCLUSION: Patients with SLE, patients with pauci-SLE, and patients with SS are more likely to have high serum IFN activity than asymptomatic individuals with SSA/Ro autoantibodies, suggesting that these autoantibodies are insufficient for activation of the type I IFN pathway, and that disease-specific factors are important for type I IFN generation in vivo.     

Comparison of different methods for the detection of anti-Ro/SSA antibodies in connective tissue diseases

OBJECTIVE: To compare the performance characteristics of various tests commonly used to detect anti-SSA/Ro autoantibodies in the sera of patients affected by connective tissue diseases (CTD). METHODS: Indirect immunofluorescence (IIF) with HEp-2000 as substrate (ImmunoConcepts, USA), Ouchterlony's double immunodiffusion (ID) (home made), commercial Varelisa ReCombi anti-Ro kit (Pharmacia & Upjohn, Germany), research kits (60 kDa and 52 kDa) with human recombinant antigens (Pharmacia & Upjohn, Germany) and a commercial western blot (WB) kit (MarDx, USA) were evaluated in our study. Sixty-four sera from patients affected by CTD were tested: 15 had primary Sj?gren's syndrome (SS), 34 only had sicca syndrome, and 15 had systemic lupus erythematosus (SLE). Thirty sera from healthy subjects were selected as controls. RESULTS: 54 sera were positive by at least one method. The specificity of all tests was good. The prevalence of anti-SSA antibodies on 54 positive sera was 76% (ID), 89% (IIF), 89% (Varelisa), 89% (ELISA Ro-60 kDa), 67% (ELISA Ro-52 kDa) and 85% (WB). Some differences were found between WB and ELISA in the detection of anti-60 kDa SSA and anti-52 kDa SSA; in 3 SS sera only anti-52 kDa protein was found by WB. CONCLUSION: Our data confirm that, although IIF HEp 2000 (Immuno Concepts) and Varelisa anti-Ro (Pharmacia & Upjohn) both performed well, a combination of 2 or more methods must still be recommended for anti-SSA antibody detection.     

THE MOLECULAR BASIS OF THE SSA/Ro ANTIGENS AND THE CLINICAL SIGNIFICANCE OF THEIR AUTOANTIBODIES

The SSA/Ro antigens are nuclear and cytoplasmic polypeptideswhich serve as autoantigens in systemic lupus erythemato-sus(SLE) and Sjögren's syndrome (SS). They contain two majorisoforms of 60 and 52 kD. The former is the native antigen whilethe latter is a major autoantigen in its denatured form. A thirdprotein of 46 kD termed ‘calreticulin-Ro’ is anautoantigen found in the sera of some patients with SLE. However,it is probably unrelated to the SSA/Ro system. The clinicalrelevance of anti SSA/Ro antibodies in rheumatic diseases hasalso been considered. Initially these antibodies were thoughtto be an epiphenomenon of autoimmune diseases. Recent studieshave shown that they are associated with specific clinical manifestationsand disease subsets. Furthermore, animal models have demonstratedthat they may enhance tissue damage. It seems that anti-SSA/Roantibodies may play a role in the pathogenicity of SLE and SS. KEY WORDS: SSA/Ro antigen, Autoantibodies, Systemic lupus erythematosus, Sjögren's syndrome