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     

Intra- and intermolecular spreading of autoimmunity involving the nuclear self-antigens La (SS-B) and Ro (SS-A).

We have tested the extent of immune self-tolerance to the ubiquitously expressed nuclear/cytoplasmic autoantigens La (SS-B) and Ro (SS-A) in healthy, nonautoimmune mice. Immunization of mice with recombinant mouse La resulted in a specific, isotype-switched autoantibody response, which was initially directed toward the La C subfragment (aa 111-242) but rapidly spread to involve the La A (aa 1-107) and La F (aa 243-345) regions of the La antigen. Intramolecular spreading of the anti-La antibody response was further demonstrated by the appearance of autoantibodies to multiple, nonoverlapping antigenic regions of La, after immunization of mice with the 107-aa La A subfragment. Moreover, immunization of mice with recombinant mouse or human La also elicited specific anti-60-kDa Ro IgG antibodies in all strains tested. Mice immunized with 60-kDa Ro produced a high titer anti-Ro antibody response, which was also associated with intermolecular spreading, resulting in the specific appearance of anti-La autoantibodies. These findings show that the development of autoantibodies to multiple components of the La/Ro ribonucleoprotein complex may follow initiation of immunity to a single component. In addition, the data reveal the incomplete nature of immune tolerance to La and Ro despite their endogenous expression in all nucleated cells. These observations are likely to account for the coexistence of anti-La/Ro antibodies in autoimmune disease and suggest a general explanation for the appearance of mixed autoantibody patterns in systemic autoimmune disorders.     

Importance of the immune response to the Ro/La particle in the development of congenital heart block and neonatal lupus erythematosus

Previous studies have suggested a role for anti-Ro antibodies in the pathogenesis of neonatal lupus erythematosus (NLE). We reexamined the role of the immune response to the Ro/La particle in the development of NLE using newer and more definitive assay techniques. All 15 infants with congenital heart block and NLE had both anti-Ro and anti-La antibodies. Of 8 patients with cutaneous NLE alone, 2 had anti-Ro antibodies alone while the remaining 6 had both anti-Ro and anti-La antibodies. One woman gave birth to 2 children; one had both Ro and La antibodies and developed congenital heart block, the other had only anti-Ro and anti-U1RNP antibodies and was clinically normal. Our study demonstrates that the presence of anti-Ro and anti-La antibodies define the immune response that is associated with the development of congenital heart block of NLE.     

Molecular characterization of Ro(SSA) and La(SSB) proteins

Ro(SSA) and La(SSB) proteins were characterized using human spleen extract as antigen and monospecific anti-Ro(SSA) and anti-La(SSB) sera. The antigens were partially purified by DEAE cellulose and Sephacryl chromatography, and then were electrotransferred to nitrocellulose sheets after SDS-PAGE electrophoresis. The anti-Ro(SSA) sera had reacted with a polypeptidic band of 58 kilodaltons (kDa), meanwhile the La(SSB) antisera reacted with 2 polypeptidic bands of 42 and 40 kDa. The molecular weight of the Ro(SSA) and La(SSB) proteins obtained by gel filtration chromatography was in agreement with the PAGE/electrotransfer results. These procedures are useful tools for the molecular analysis of the markers in the connective tissue diseases.     

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.     

Anti-Ro52 reactivity is an independent and additional serum marker in connective tissue disease

OBJECTIVE: To determine whether anti-Ro52 is an independent serum marker in connective tissue disease. METHODS: Over a two year period, 1727 consecutive antinuclear antibody (ANA) positive serum samples were analysed in parallel by double immunodiffusion with thymus/spleen nuclear extract and by line immunoassay with recombinant Ro52, recombinant La/SSB, and natural Ro60. Sera that were only reactive towards Ro52 were further analysed by a variety of additional anti-SSA/Ro detection methods and by specific anti-Ro52 and anti-Ro60 assays. Natural purified SSA/Ro was analysed by immunoblot and protein sequencing. RESULTS: Analysis of natural purified SSA/Ro (Immunovision, Springdale, AR) showed only Ro60 and no immunoreactive Ro52. Consequently, assays based on this substrate only identify sera with anti-Ro60 reactivity. Twenty serum samples showed anti-Ro52 without anti-Ro60 and anti-SSB/La on line immunoassay. By additional testing, 2/20 sera were found positive for anti-Ro60 reactivity. The remaining 18 sera were not identified by any of the classical anti-SSA/Ro assays and were considered to be reactive only with Ro52 and not with Ro60. This anti-Ro52 reactivity was confirmed by natural and recombinant Ro52 in 16/18 cases. 12/18 sera corresponded to connective tissue diseases. CONCLUSION: Anti-Ro52 positive sera without any evidence of anti-Ro60 and anti-La/SSB reactivity can be considered as an independent group that is systematically missed by classical anti-SSA/Ro detection methods owing to a bias towards anti-Ro60 reactivity. The anti-Ro52 sera are precipitin negative, not retrieved by SSA/Ro enzyme linked immunosorbent assays (ELISAs) based on natural SSA/Ro, and show no specific ANA fluorescence staining pattern. These findings together with the clinical data indicate that anti-Ro52 should be considered as an additional and independent serum marker.     

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.     

Ro 52kD autoantibodies are detected in a subset of ANA-negative sera

To define Ro 52kD, Ro 60kD, and La specificities of autoantibodies within ANA-negative sera, samples from 64 ANA-negative but SSA positive patients undergoing investigation due to suspected CTD were analysed, using recombinant antigens and synthetic peptides by immunoblotting and ELISA. The sera were selected from 4025 sera submitted for routine ANA analysis. Antibodies to Ro or La were detected in 42/64 sera (65%). Anti-Ro 52kD antibodies occurred most frequently and were present in 42/64 sera (65%). This was the only specificity of autoantibody detected in 18 sera. No patient had only anti-La or anti-Ro 60 antibodies. In total 18.64 patients (28%) had Ro 60 antibodies and 14/64 had anti-La antibodies (21%). Eight patients had antibodies reacting with all three antigens. We used the same set of sera to test the antigenicity of different regions of Ro 52kD represented by deletion clones and peptides derived from the Ro 52kD sequence. Out of 30 sera reacting with a recombinant deletion clone encompassing as residues 136-227, 12 sera reacted with a peptide corresponding to a 200-239. Some sera gave a low positive OD value with a peptide of a 176-196. Based on the results of this study in which we demonstrate Ro 52kD autoantibodies in 65% of selected ANA negative sera and define an autocephitope within the Ro 52kD protein composed of the leucine zipper domain, we suggest that testing for Ro 52kD antibodies could be included in an extended investigation of ANA negative patients with suspected connective tissue disease.     

Influenza virus vaccination of patients with SLE: effects on generation of autoantibodies

The sera of 24 women with SLE who received influenza vaccine were tested by ELISA for anti-DNA, anticardiolipin, anti-Sm, anti-Sm/RNP, anti-Ro and anti-La. Blood samples were withdrawn at the time of vaccination and 6 and 12 weeks after vaccination. The mean age at enrolment into the study was 46.1 years. The mean disease duration was 9.1 years. SLEDAI scores were 6.6 at vaccination, 4.9 at 6 weeks and 5.1 at week 12. The vaccine was not associated with the generation of anti-DNA. At time of vaccination a single patient had anti-Sm, four patients had anti-Sm/RNP antibodies, none of the patients had anti-La antibody and six had anti-Ro antibodies. Six weeks after vaccination four, eight, nine and three patients had autoantibodies reacting with Sm, Sm/RNP, Ro and La, respectively. Twelve weeks after vaccination none of the patients had anti-Sm, three had anti-Sm/RNP, five had anti-Ro and two had anti-La antibodies. Following vaccination six and three patients developed IgG and IgM anticardiolipin antibodies, respectively. In summary, although the influenza virus vaccine is clinically safe for patients with SLE it may trigger the generation of autoantibodies. This effect is usually short term and has no clinical significance. Received: 17 September 2001 / Accepted: 11 February 2002     

The Ro small cytoplasmic ribonucleoproteins: identification of the antigenic protein and its binding site on the Ro RNAs.

Patients with systemic lupus erythematosus and other rheumatic diseases often possess autoantibodies directed against discrete classes of small ribonucleoprotein particles (RNPs). The class of particles recognized by anti-Ro antibodies contains from two to four small cytoplasmic RNAs, depending on the mammalian species examined. We find that an antigenic polypeptide of 60 kDa is the major protein residing in Ro RNPs from human HeLa cells. To determine what common feature of Ro RNA sequence or structure is recognized by the Ro protein, we carried out ribonuclease protection experiments on isolated Ro RNPs from HeLa cells. For each of the three human Ro RNAs whose sequence is known, the most highly protected portion found in immunoprecipitates corresponded to the lower section of a stem formed by base-pairing the 5' and 3' ends of the RNA. Within this protected helix is a highly conserved region composed of seven identical base pairs with a single bulged cytidine. We discuss possible functions for the Ro RNPs.     

Differences in the fine specificity of anti-Ro (SS-A) in relation to the presence of other precipitating autoantibodies

In sera from patients with systemic lupus erythematosus or Sj?gren's syndrome, we determined the fraction of antibody that remained reactive with human Ro (SS-A) after absorption with bovine spleen extract, and the reactivity with the 60-kd and 54-kd red blood cell Ro (SS-A) bands by Western blot. Of the 3 groups of sera studied, those containing anti-Ro (SS-A) alone had the highest degree of reactivity with human Ro (SS-A) after absorption with bovine spleen extract, followed, in descending order, by sera containing anti-Ro (SS-A) and anti-La (SS-B), and sera containing anti-Ro (SS-A) and anti-nuclear RNP. The groups of sera could be distinguished on this basis. Sera with anti-Ro (SS-A) and anti-nuclear RNP could also be distinguished from the other 2 types of sera by their uniform and preferential reactivity with the 60-kd red blood cell Ro (SS-A), by Western blot analysis. These findings indicate that there are both qualitative and quantitative differences, associated with the presence of other autoantibodies, in the fine specificity of anti-Ro (SS-A) sera.     

Anti-La (SS-B): a diagnostic criterion for Sj?gren's syndrome?

We examined the diagnostic sensitivity and specificity of antibodies to Ro (SS-A) and La (SS-B) in Sj?gren's syndrome (SS) by counterimmunoelectrophoresis and immunodiffusion. Anti-Ro was found in 56% and anti-La in 42% of patients with SS and in 38% and 6% respectively in SLE. Anti-La was rare (less than 1%) in other connective tissue diseases. As a more stringent test of diagnostic specificity, 88 patients whose sera contained anti-La and/or anti-Ro were carefully examined for evidence of Sj?gren's syndrome. Of 35 patients whose sera contained anti-La, 29 (83%) fulfilled criteria for SS, and four out of 6 of the remainder showed some evidence of early disease. Of 53 patients with anti-Ro (without anti-La), only 42% had Sj?gren's syndrome, 45% had SLE and 13% other connective tissue diseases. These data confirm that anti-La, but not anti-Ro, has a high diagnostic specificity for Sj?gren's syndrome and merits inclusion as separate diagnostic criterion for the disease.     

Anti-La/SSB antibodies transported across the placenta bind apoptotic cells in fetal organs targeted in neonatal lupus

OBJECTIVE: To determine whether La and/or Ro epitopes on apoptotic cells in fetal organs that are targeted in neonatal lupus syndrome (NLS) are accessible for binding by autoantibodies in vivo, we traced the fate of transplacental autoantibodies in a murine passive transfer model. METHODS: Pregnant mice at day 15 of gestation (E15) were injected intraperitoneally with human anti-Ro/La-positive sera or control sera, and transplacental transfer of human autoantibodies was tested by enzyme-linked immunosorbent assay with recombinant antigens. Multiple cryostat sections at the level of the heart of E17 fetuses were visualized simultaneously for human IgG binding and apoptosis (TUNEL) under confocal microscopy. Serial paraffin sections of E17 and E19 fetuses were examined for histologic evidence of inflammation. RESULTS: Human IgG anti-52-kd Ro, anti-60-kd Ro, and anti-La autoantibodies were transported efficiently into the fetal circulation. Human IgG-apoptotic cell complexes were detected in the heart (atrial trabeculae and atrioventricular node), skin, liver, and newly forming bone of fetuses from mothers injected with anti-Ro/La sera but not control sera. The IgG binding was fetal-specific and organ-specific; transplacental autoantibodies did not bind to apoptotic cells in the fetal thymus, lung, brain, or gut. The complexes were not associated with an inflammatory reaction. Injection of mothers with affinity-purified anti-La autoantibodies (but not anti-Ro/La Ig depleted of anti-La) revealed an identical location of IgG binding to apoptotic cells in the fetuses. CONCLUSION: This is the first study to demonstrate that transplacental anti-La autoantibodies bind specifically to apoptotic cells in selected fetal organs in vivo, similar to the organ involvement in NLS. We hypothesize that additional factors are required to promote proinflammatory clearance of IgG-apoptotic cell complexes and subsequent tissue damage.     

Two Ro (SS-A) autoantibody responses in systemic lupus erythematosus. Correlation of HLA-DR/DQ specificities with quantitative expression of Ro (SS-A) autoantibody

Autoantibodies to Ro (SS-A), La (SS-B), and Sm/nuclear RNP were quantitated by enzyme-linked immunosorbent assay in 106 white patients with systemic lupus erythematosus. Two Ro autoantibody subgroups were identified that differed quantitatively, genetically, and clinically. The subgroup having anti-Ro only demonstrated significantly lower mean anti-Ro levels than did the subgroup with concomitant anti-La and showed a strong association with the linked HLA alleles DR2 and DQw1. The anti-Ro with anti-La subgroup was associated with the linked HLA alleles B8, DR3, DRw52, and DQw2 (DR3 was primary), and this subgroup consisted of patients with older ages at disease onset, sicca complex, and less renal involvement. Overall, the relative risk (RR) for having anti-Ro was highest in HLA-DR2/DR3 heterozygotes compared with non-DR2/DR3 heterozygotes (RR 15) and all other DR combinations (RR 7), suggesting a compound effect of 2 immune responses. Heterozygotes for HLA-DQw1/DQw2 demonstrated significantly higher mean levels of anti-Ro, which may be indicative of trans gene interaction at HLA-DQ. These data suggest the hypothesis that HLA genes exert their major effects on Ro/La autoantibody subsets of systemic lupus erythematosus.     

Autoantibodies and their target antigens in Sj?gren's syndrome.

The subject of this review is the humoral autoimmune response in Sj?gren's syndrome. Autoantibodies in this disease are primarily directed against the Ro/SS-A and La/SS-B autoantigens and against IgG (rheumatoid factor). The Ro/SS-A and La/SS-B autoantigens consist of a number of antigenic proteins coupled to small RNA molecules. These RNA-protein particles are present in all human cells and are strongly conserved throughout various species. Anti-Ro/SS-A and anti-La/SS-B autoantibodies can be detected using counter-immunoelectrophoresis, immunoblotting technique, ELISA or RNA precipitation assays. The preferred method of screening for anti-Ro/SS-A antibodies in human sera is counter-immunoelectrophoresis; anti-La/SS-B antibodies are best detected with the immunoblotting technique. Anti-Ro/SS-A antibodies are found in 60% of patients with Sj?gren's syndrome, but are not specific markers for this disease. Anti-La/SS-B antibodies are present in approximately 40% of patients with Sj?gren's syndrome; the only other disease where the antibody has been detected is systemic lupus erythematosus (15% positive). The origin and possible pathogenetic role of autoantibodies in Sj?gren's syndrome is still unclear. Our view is that the current evidence supports a mechanism whereby autoantibodies are the product of an oligoclonal B-cell proliferation. The only instance where autoantibodies probably play a direct pathogenetic role is the occurrence of congenital heart block in the offspring of anti-Ro/SS-A and anti-La/SS-B positive mothers.     

Detection of serum antibodies to retroviral proteins in patients with primary Sj?gren's syndrome (autoimmune exocrinopathy)

Primary Sj?gren's syndrome (SS) is considered a benign autoimmune disease; it is characterized by lymphoid infiltration of salivary and lacrimal glands, often accompanied by the presence of serum autoantibodies, particularly anti-Ro (SS-A) and anti-La (SS-B). There are important immunologic similarities between primary SS and acquired immunodeficiency syndrome. To investigate for a possible immune response to retroviral proteins in primary SS, we performed immunoblotting against human immunodeficiency virus-1 (HIV-1) proteins using sera from 47 patients with primary SS. Moderate-to-strong reactivity, suggesting the presence of serum antibodies, was found in 14 patients (30%). Of 120 normal subjects, only 1 showed moderate positivity. All 14 positive SS sera reacted against p24 (gag) but failed to react against gp41 or gp120 (env). This response did not reflect hypergammaglobulinemia since immunoglobulin concentrations among the 29 SS patients studied were the same in sera that contained and sera that did not contain anti-gag reactivity. Two sera also reacted against p17 gag. Four reacted against HIV-2 core proteins, but none reacted with core proteins of human T lymphotropic virus-I. Only 1 of the 14 sera reacted against Ro (SS-A), and 1 other reacted against La (SS-B). These results identify a subset of SS patients characterized by 1) the presence of serum antibodies to HIV-1 group-specific, but not type-specific, proteins, and 2) the relative absence of anti-Ro (SS-A) and anti-La (SS-B) autoantibodies. In this latter respect, these SS patients constitute a subpopulation that resembles patients with HIV-induced SS-like disease.     

T cell epitopes of the La/SSB autoantigen in humanized transgenic mice expressing the HLA class II haplotype DRB1*0301/DQB1*0201

OBJECTIVE: T cells are implicated in the production of anti-La/SSB and anti-Ro/SSA autoantibodies commonly associated with the DR3/DQ2 haplotype in systemic lupus erythematosus and Sj?gren's syndrome. This study was undertaken to investigate the DR3/DQ2-restricted T cell response to wild-type human La (hLa) and a truncated form of mutant La. METHODS: Humanized transgenic mice expressing HLA-DRB1*0301/DQB1*0201 (DR3/DQ2) were immunized with recombinant antigen and examined for development of autoantibodies and T cell proliferation against overlapping peptides spanning the La autoantigen. HLA restriction and peptide binding of identified T cell epitopes to DR3 or DQ2 were determined using blocking monoclonal antibodies and a direct binding assay. RESULTS: DR3/DQ2-transgenic mice generated an unusually rapid class-switched humoral response to hLa with characteristic spreading to Ro 52 and Ro 60 proteins following hLa protein immunization. Seven T cell determinants in hLa were restricted to the HLA-DR3/DQ2 haplotype. Six epitopes tested were restricted to HLA-DR and bound DR3 with semiconserved DR3 binding motifs. No DQ restriction of these epitopes was demonstrable despite efficient DQ binding activity in some cases. No neo-T cell epitopes were identified in mutant La; however, T cells primed with mutant La exhibited a striking increase in proliferation to the epitope hLa(151-168) compared with T cells primed with hLa. CONCLUSION: Multiple DR3-restricted epitopes of hLa have been identified. These findings suggest that truncation of La produced by somatic mutation or possibly granzyme B-mediated cleavage alters the immunodominance hierarchy of T cell responsiveness to hLa and may be a factor in the initiation or maintenance of anti-La 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.     

Anti-Ro (SSA) antibodies in rheumatoid arthritis patients with gold-induced side effects

The purpose of our study was to investigate the significance of the presence of anti-Ro antibodies found by us in an earlier study of rheumatoid arthritis (RA) patients with gold-induced side effects. Sera of 29 anti-Ro (SSA) positive RA patients who had gold-induced side effects were studied. All sera were examined by Western blot using recombinant antigens, encoding the Ro 60 kD and the La proteins. HLA typing was done in all patients. Thirteen patients reacted only with the Ro 52 kD antigen and all had severe skin eruptions caused by gold therapy. Another ten patients who reacted only with the Ro 60 kD antigen had other side effects to gold (six had proteinuria and four leucopenia). Six patients who reacted to all three antigens (Ro 52 kD, Ro 60 kD and La) had secondary Sjögren's syndrome. No significant statistical differences were noted in the incidence of HLA-DR3 between the subgroups of patients. Our data indicated that antibodies to the Ro 52 kD antigen are associated with skin eruptions in RA patients treated with gold.     

Two ro (ss-a) autoantibody responses in systemic lupus erythematosus

Autoantibodies to Ro (SS-A), La (SS-B), and Sm/nuclear RNP were quantitated by enzyme-linked immunosorbent assay in 106 white patients with systemic lupus erythematosus. Two Ro autoantibody subgroups were identified that differed quantitatively, genetically, and clinically. The subgroup having anti-Ro only demonstrated significantly lower mean anti-Ro levels than did the subgroup with concomitant anti-La and showed a strong association with the linked HLA alleles DR2 and DQw1. The anti-Ro with anti-La sub-group was associated with the linked HLA alleles B8, DR3, DRw52, and DQw2 (DR3 was primary), and this subgroup consisted of patients with older ages at disease onset, sicca complex, and less renal involvement. Overall, the relative risk (RR) for having anti-Ro was highest in HLA-DR2/DR3 heterozygotes compared with non-DR2/DR3 heterozygotes (RR 15) and all other DR combinations (RR 7), suggesting a compound effect of 2 immune responses. Heterozygotes for HLA-DQw1/DQw2 demonstrated significantly higher mean levels of anti-Ro, which may be indicative of trans gene interaction at HLA-DQ. These data suggest the hypothesis that HLA genes exert their major effects on Ro/La autoantibody subsets of systemic lupus erythematosus.