Autoantibodies to chromatin: prevalence and clinical significance in juvenile rheumatoid arthritis

OBJECTIVE: To determine the prevalence of anti-chromatin antibodies (Abs) in juvenile rheumatoid arthritis (JRA) and to assess any association between the presence of anti-chromatin Abs and clinical subsets of the disease. METHODS: IgG anti-chromatin Abs and anti-extractable nuclear antigens (ENA) Abs were detected by an enzyme-linked immunosorbent assay (ELISA), and antinuclear Abs (ANA) by indirect immunofluorescence in sera of 89 children with JRA. Ten children with systemic, 32 with polyarticular and 47 with pauciarticular disease onset (uveitis occurred in 17/47 children) were studied. As a control group, 12 sera of patients suffering from idiopathic uveitis and 31 age- and-sex-matched healthy children (HC) were examined. RESULTS: Abs to chromatin were detected in 14/47 (29.8%) of children suffering from pauciarticular onset JRA and in this group the higher prevalence of anti-chromatin Abs has been found in children with chronic uveitis (p = 0.002). Anti-chromatin positivity was observed in 2/10 (20%) of systemic and in 3/32 (9.3%) of polyarticular onset JRA. Furthermore, none of the patients with idiopathic uveitis and HC had Abs to chromatin. anti-chromatin Abs titers remained relatively stable over a 6-month control period. CONCLUSION: Our results confirm previous data about the presence of circulating anti-chromatin Abs in juvenile arthritis. Interestingly, anti-chromatin Abs were significantly higher in the group of patients with pauciarticular onset with past or present history of uveitis, than in patients without ocular involvement. A long-term follow-up study could be useful to demonstrate the potential utility of these autoantibodies in diagnosing, classifying and treating children affected.     

T/non-T and CD4/non-T cell autologous mixed lymphocyte reactions in juvenile rheumatoid arthritis

Proliferation of T and CD4 cells in the autologous mixed lymphocyte reaction (AMLR) was determined for children with juvenile rheumatoid arthritis (JRA) and children with other rheumatic and connective tissue diseases. Children with musculoskeletal symptoms but no rheumatic disease and healthy adults served as controls. Patients with polyarticular rheumatoid factor (RF) positive JRA had a diminished CD4/non-T cell AMLR, whereas those with RF negative polyarticular and pauciarticular onsets had normal results.     

Circulating immune complexes and antinuclear antibodies in juvenile rheumatoid arthritis

Materials with the Clq binding properties of soluble immune complexes (IC) were found in sera from 11 of 51 consecutive (22%) children with juvenile rheumatoid arthritis (JRA) and in 17 of 20 adults with active sero-positive rheumatoid arthritis (RA). IC appeared more frequently in children with systemic onset disease whereas antinuclear antibody (ANA) was found more frequently in sera from those with pauciarticular disease. Only 3 JRA sera contained anti-immunoglobulin (rheumatoid factor); those 3 also had high Clq binding activities. Seven of 50 patients (14%) carried HLA-B27 but B27 was not associated with high Clq binding activity or presence of ANA. The presence of free ANA more frequently in children with mild disease and IC more frequently in children with relatively severe disease suggests that children with systemic JRA may have a relative defect in antibody-forming capacity or reticuloendothelial function which results in decreased clearance of circulating IC. Alternatively, systemic, polyarticular, and pauciarticular JRA may represent a spectrum of clinically similar diseases resulting from different etiologic agents.     

DNA analysis of HLA-DR, DQ, and DP alleles in children with polyarticular juvenile rheumatoid arthritis.

HLA-DR, DQ and DP alleles were determined by restriction fragment length polymorphism analysis and oligonucleotide probe hybridization of polymerase chain reaction amplified genomic DNA in 94 Caucasian children with polyarticular juvenile rheumatoid arthritis (JRA) [13 rheumatoid factor (RF)+ and 81 RF-] and 100 healthy controls. HLA-DRw8, DQw4, DQA1*0401, DQB1*0402 were increased in frequency in those patients with RF seronegative disease, with highest frequencies seen in patients with young age at onset (< 5 years of age). These findings were similar to what we observed in children with pauciarticular JRA, especially those with young age at onset. DPB1*0301 was also found in increased frequency in the RF- group, and in particular those seronegative for antinuclear antibody. In contrast to what is observed in patients with pauciarticular JRA, the frequency of DPB1*0201 was not increased in any polyarticular JRA patient group. These data suggest that polyarticular JRA shares many genetic features with pauciarticular JRA.     

Antibodies to histones H1 and H5 in sera of patients with juvenile rheumatoid arthritis

The specificity of juvenile rheumatoid arthritis (JRA) sera for histone subclasses was examined by immunoblotting. Antibodies to H1 alone were found in 4 of 21 pauciarticular-onset JRA sera, 4 of 19 polyarticular-onset JRA sera, and 2 of 11 systemic-onset JRA sera. Antibodies to H5 alone were found in 1 of 21 pauciarticular JRA sera, 1 of 19 polyarticular JRA sera, and 3 of 11 systemic JRA sera. Antibodies to both H1 and H5 were found in 4 of 21 pauciarticular JRA sera, 4 of 19 polyarticular JRA sera, and 1 of 11 systemic JRA sera. Antibodies to the core histones (H2A and H2B) were found in 1 of 21 pauciarticular JRA sera, 1 of 19 polyarticular JRA sera, and no systemic JRA sera. No reactivity to histones was observed in 30 sera from age-matched children with nonrheumatic diseases. The presence of H1 and H5 antibodies did not correlate with antinuclear antibody titers or with a homogeneous pattern of immunofluorescence. The predominance of H1 and H5 antibodies and relative absence of antibodies binding to core histones in JRA contrast with findings in adult systemic lupus erythematosus. Further, the presence of antibodies to H5 alone in some of the JRA patients indicates that the immune response in these patients is directed to determinants that are not shared by sequences of mammalian proteins.     

Increased circulating vascular endothelial growth factor is correlated with disease activity in polyarticular juvenile rheumatoid arthritis.

OBJECTIVE: To investigate the relevance of vascular endothelial growth factor (VEGF) in the pathogenesis of juvenile rheumatoid arthritis (JRA). METHODS: Serum VEGF levels in 58 patients with JRA (systemic in 17, polyarticular in 29, pauciarticular in 12) were measured by ELISA and compared with those of 21 patients with infectious diseases and 50 healthy children. Correlations of VEGF levels with number of joints with active arthritis, erythrocyte sedimentation rate (ESR), and hyaluronic acid (HA) were examined. RESULTS: Serum levels of VEGF in patients with JRA were significantly higher than in healthy controls. Patients with systemic and polyarticular JRA showed statistically higher levels of VEGF than those with infectious diseases. VEGF levels correlated statistically with C-reactive protein (CRP) in patients with both infectious diseases and polyarticular JRA, but the regression slope (VEGF/CRP) was much steeper in polyarticular JRA than in infectious diseases. Serum VEGF levels correlated with disease activity variables such as the number of joints with active arthritis, ESR, and serum HA levels in polyarticular JRA. CONCLUSION: The correlation of serum VEGF levels and disease activity in polyarticular JRA suggests that VEGF may take an active part in joint inflammation.     

Clinical relevance of IgA rheumatoid factor (RF) in children with juvenile rheumatoid arthritis

This study proposed to investigate the prevalence and clinical relevance of serum immunoglobulin A (IgA) rheumatoid factor (RF) in juvenile rheumatoid arthritis (JRA) as published reports vary in their conclusion. Sera of 82 children with JRA and 25-age and sex-matched healthy children were measured for IgA RF by an enzyme linked immunoassay using human IgG as the antigen. Forty-three percent of the disease population were positive and the prevalence in pauciarticular, polyarticular and systemic onset was 9/18 (50%), 21/47 (44.7%) and 5/17 (27.7%) respectively when mean + 2SD of normal was taken as the cut-off value. By defining the upper limit of normal as mean + 6SD, 16/47 (34%) were positive in the polyarticular as compared to 2/18 (11.1%) in pauciarticular and 1/17 (5.8%) of systemic onset disease groups. The prevalence in the polyarticular subset with the upper cut-off limit was significantly higher than the pauciarticular and the systemic onset group (P < 0.05). Furthermore, the mean level of IgA RF was significantly higher in the polyarticular group compared to the mean level in the systemic onset group (P < 0.05). The mean level of IgA RF was also significantly higher (P < 0.05) in 61 children with active diseases. Received: 29 January 1999 / Accepted: 10 August 1999     

Clinical comparison of cultured human epithelial cells and rat liver as substrates for the fluorescent antinuclear antibody test

Fluorescent antinuclear antibody (ANA) testing was performed on 141 sera from 114 patients with well defined rheumatic diseases including fibrositis syndrome and 24 sera from 24 healthy subjects using HEp-2 cells and rat liver as substrates. ANA titers were almost always higher on HEp-2, in most cases by 1:5 dilutions. ANA positivity or negativity was usually substrate independent, but there were exceptions. Two patients with SLE were ANA positive on HEp-2 only and rat liver only, respectively; patterns were homogeneous. Thirteen of 15 CREST patients had anticentromere antibodies, detected on HEp-2 only. "False-positive" ANA were invariably low titer, speckled and confined to one substrate.     

Antibody to streptococcal cell wall peptidoglycan-polysaccharide polymers in sera of patients with juvenile rheumatoid arthritis but absent in isolated immune complexes

Sera of 88 children with juvenile rheumatoid arthritis (JRA) (10 seropositive, polyarticular onset, 29 seronegative, polyarticular onset, 32 pauciarticular onset, and 17 systemic onset) were evaluated for the presence of serum antibodies to streptococcal cell wall peptidoglycan-polysaccharide polymers (PG-PSP). Immune complexes (IC) isolated by the antihuman IgM (HIgM) affinity column method were also evaluated for the presence of antibodies to PG-PSP. Forty-one of 88 patients with JRA (7 of 10 seropositive, polyarticular onset, 11 of 29 seronegative, polyarticular onset, 16 of 32 pauciarticular onset, and 7 of 17 systemic onset) showed elevated levels of antibodies to PG-PSP in their sera. IgM rheumatoid factors (RF) were demonstrated in 70/88 isolated IC fractions of patients with JRA and IgG RF in 7; however, none of the patients demonstrated the presence of antibodies to PG-PSP in their isolated IC fractions from the anti-HIgM affinity column. These data indicate that antibodies are produced to PG-PSP in all JRA onset types, but they are not constituents of isolated IC by the anti-HIgM affinity column method.     

Autoantibodies to chromatin components in juvenile rheumatoid arthritis

Objective. To characterize autoantibodies to chromatin components in patients with juvenile rheumatoid arthritis (JRA). Methods. The sera of 50 children with JRA were analyzed for antinuclear antibodies (ANA) by immunofluorescence and enzyme-linked immunosorbent assay (ELISA) techniques. Results. By immunofluorescence, ANA and antibodies to high-mobility group proteins or to DNA-free histones were common in patients with pauciarticular JRA and rheumatoid factor–positive polyarticular JRA. However, reactivity with histone–DNA complexes was rare. Conclusion. Because antihistone antibodies detected by ELISA failed to bind chromatin or other histone–DNA complexes, they are not likely to represent the immunofluorescent ANA activity in serum.     

Use of ELISA to measure antinuclear antibodies in children with juvenile rheumatoid arthritis.

OBJECTIVE: To compare a series of commercial ELISA tests with an indirect immunofluorescent antibody (IFA) test for the detection of antinuclear antibodies (ANA) in children with juvenile rheumatoid arthritis (JRA). METHODS: Sera from 178 patients with JRA (88 pauciarticular, 68 polyarticular, 22 systemic) were compared with 26 healthy pediatric subjects. Twenty-one samples from patients with systemic lupus erythematosus (SLE) were also tested. All samples were analyzed by IFA and by 3 commercial ELISA methods. Concordance of ELISA results with IFA results (selected standard) were used as a measure of performance. Sensitivity and specificity were calculated for each test and likelihood ratios (LR) were established for IFA and ELISA in pauciarticular and polyarticular JRA sera. The increment in pretest probability was then obtained for each test as an additional measure of test performance. RESULTS: IFA rendered positive results on 18-77% of the JRA sera depending upon the subset, 100% of SLE sera, and 15% of normal patient sera. Using IFA as the standard, correspondence with positive results among patients with JRA ranged from 0 to 74% for the 3 ELISA tests, while it ranged from 5 to 73% in IFA negative sera. IFA tests showed intermediate range likelihood ratios (0.3, 0.5, 3.5, and 5) and increments in pretest probability ranging from 25 to 45%. While one of the ELISA tests attained 50% of increment in pretest probability for the positive test, it showed 0% increment as a negative test. The other 2 ELISA tests incremented the pretest probability from 0 to 25%. CONCLUSION: Our findings indicate that in JRA, the lack of correspondence with the historic standard IFA precludes the use of ELISA tests for detection of ANA. In addition, IFA out-performs ELISA by a substantial degree when "clinical utility" analysis of test performance is utilized. Detection of ANA in children with JRA should either continue to rely on IFA or be based on a different set of antigens if an ELISA format is chosen.     

Antibodies against cyclic citrullinated peptide are associated with HLA–DR4 in simplex and multiplex polyarticular‐onset juvenile rheumatoid arthritis

Objective

Anti–cyclic citrullinated peptide (anti‐CCP) antibodies have been detected in patients with juvenile rheumatoid arthritis (JRA), particularly in those with polyarticular, rheumatoid factor (RF)‐positive JRA. Our objectives were to determine whether anti‐CCP antibodies are associated with HLA–DR4 in children with polyarticular JRA, whether anti‐CCP antibodies are associated with clinical features of disease, and whether affected sibling pairs (ASPs) with JRA are concordant for this antibody.

Methods

Stored serum samples obtained from 230 HLA‐typed patients with JRA (77 with polyarticular‐onset disease and 153 with pauciarticular‐ or systemic‐onset disease), 100 JRA ASPs, and 688 healthy children were tested for anti‐CCP antibodies and RF.

Results

Thirteen percent of the patients with polyarticular‐onset JRA and 2% of the other JRA patients exhibited anti‐CCP antibodies, compared with only 0.6% of the controls. Fifty‐seven percent of RF‐positive patients with polyarticular‐onset JRA had anti‐CCP antibodies. HLA–DR4–positive patients with polyarticular‐onset JRA were more likely to have anti‐CCP antibodies than were those without HLA–DR4 alleles (odds ratio [OR] 5.20, 95% confidence interval [95% CI] 1.30–20.9). Anti‐CCP antibodies were associated with polyarticular onset (OR 7.46, 95% CI 1.99–28.0), a polyarticular disease course (OR 9.78, 95% CI 1.25–76.7), and erosive disease (OR 14.3, 95% CI 3.01–67.9). Concordance rates for anti‐CCP antibodies among ASPs were statistically significant.

Conclusion

These data demonstrate increased anti‐CCP antibody formation in HLA–DR4–positive patients with polyarticular‐onset JRA. The overall prevalence of anti‐CCP antibodies in JRA is low, but a substantial proportion of RF‐positive patients with polyarticular‐onset JRA have these antibodies. Anti‐CCP antibodies in JRA are associated with polyarticular onset, a polyarticular course, and erosive disease.

     

Antibody to ribonucleoprotein in pauciarticular juvenile rheumatoid arthritis

Sera from 8 children with pauciarticular juvenile rheumatoid arthritis (JRA) were studied to determine the nuclear antigen to which antinuclear antibody (ANA) is directed. No patient had antibody to native DNA, nuclear histones, or saline soluble nuclear antigens. Trypsin treatment of the nuclear substrate abrogated ANA staining for all sera tested, while RNase treatment abrogated ANA activity for 6 of 8 sera. These results indicate that ANA in most patients with pauciarticular JRA is directed to a ribonucleoprotein that requires both RNA and protein moieties for antigenic integrity.     

Early predictors of longterm outcome in patients with juvenile rheumatoid arthritis: subset-specific correlations

OBJECTIVE: To determine early predictors of longterm outcome in juvenile rheumatoid arthritis (JRA) in a multicenter cohort. METHODS: Patients were selected if they were > or = 8 years of age; the onset of arthritis occurred > or = 5 years before study; and a diagnosis of JRA was made at a participating center. Outcome variables were scores on self-administered Childhood Health Assessment Questionnaires (CHAQ) and active disease duration. Possible explanatory variables assessed included characteristics present at onset, HLA alleles, in particular the rheumatoid arthritis associated shared epitope (RASE), and radiographic indicators of joint damage within 2 years of onset. Data for 393 patients were available. Multivariate analyses were performed for the total group and for each onset subtype. RESULTS: Male sex correlated with worse disability in systemic onset JRA but less disability in RF negative, and a shorter active disease duration in RF positive polyarticular onset JRA. Positive antinuclear antibody correlated with a longer active disease duration in patients with pauciarticular onset JRA. Younger age at onset predicted longer active disease duration in pauciarticular and RF negative polyarticular, and a shorter active disease duration in systemic onset JRA. Residence on a reserve, rather than native North American race, correlated with worse disability. The RASE correlated with less disability in systemic JRA; but no correlation with outcome was evident for patients with rheumatoid factor positive polyarticular JRA. CONCLUSION: Variables predictive of longterm outcome in JRA are specific for each onset subtype. The most important early predictors were age at onset and sex of the patient. Place of residence may have a greater effect on disability than race. RASE may associate with a more favorable outcome in systemic onset disease.     

Analysis of the HLA-DR gene frequencies in Japanese cases of juveniles rheumatoid arthritis and rheumatoid arthritis by oligonucleotide DNA typing

Summary HLA-DR gene frequencies in 59 Japanese children with juvenile rheumatoid arthritis (JRA) and 62 Japanese adults with rheumatoid arthritis (RA) were analyzed by oligonucleotide DNA typing. As in other studies, the frequency of DRB1*0405 in RA patients was significantly higher than in the Japanese controls. In a comparison of non-calssified JRA patients with Japanese controls, no significant differences were observed in the frequency of DR types. However, when the JRA patients were classified into four clinical types, i.e., a rheumatoid factor-positive [RF(+)] polyarticular type, a rheumatoid factor-negative [RF(-)] polyarticular type, a pauciarticular type, and a systemic onset type, DRB1*0405 was found to be significantly higher in the RF(+) polyarticular JRA patients than in the controls (P>0.05). Thus, the RF(+) polyarticular type of JRA had the same HLA association as RA. This result is consistent with the fact that both RF(+) polyarticular JRA and RA cases have a similar clinical course.     

Immunoregulatory defects in juvenile rheumatoid arthritis. Comparison between patients with the systemic or polyarticular forms

Studies of cellular immunity in juvenile chronic arthritis (juvenile rheumatoid arthritis, JRA) have been scant, controversial, or have not addressed the issue of the different forms of the disease. We studied 23 patients with JRA of either systemic (n = 8) or polyarticular (n = 15) type of onset and compared the findings to those made in 10 healthy children of similar age. Both groups of patients with JRA were found to have increased CD8 T cells, normal production of interleukin-1 and 2 and decreased production of B cell stimulatory factor in their peripheral blood. In addition, patients with systemic JRA were found to have decreased spontaneously expanded and concanavalin-A induced suppressor functions. These findings in both forms of JRA are distinguishable from those that have been made in other connective tissue diseases including the adult form of rheumatoid arthritis.     

Juvenile rheumatoid arthritis: linkage to HLA demonstrated by allele sharing in affected sibpairs

OBJECTIVE: To test for linkage between the HLA region and juvenile rheumatoid arthritis (JRA), with stratification by onset and course types, in a cohort of affected sibling pairs (ASPs). METHODS: Eighty pairs of siblings with JRA who were registered with the Research Registry for JRA ASPs (sponsored by the National Institute of Arthritis and Musculoskeletal and Skin Diseases) were typed for HLA-DR. The observed ratio of sharing of none, one, or both parental DR alleles was compared against the expected ratio of 1:2:1 by goodness-of-fit chi-square tests. A group of 265 unrelated control subjects served as a comparison population for HLA-DR allele frequencies among patients, by Fisher's exact test. RESULTS: Overall, there was excess sharing of 2 DR alleles among ASPs with JRA. The observed ratio of sharing 0, 1, or 2 DR alleles was 8:40:32, instead of the expected ratio of 20:40:20 (P < 0.001). When stratified by JRA onset type, excess allele sharing was demonstrated among ASPs who were concordant for onset type (P = 0.002). This was true for both pauciarticular and polyarticular onset. When stratified by disease course, excess allele sharing was also demonstrated among ASPs who were concordant for disease course (P < 0.001). This was true for both the pauciarticular and the polyarticular course. Among the 32 ASPs who shared two DR alleles, 5 pairs had both DR8 and DR11, which was significantly more frequent (P < 0.0001) than the incidence in the control group (n = 0). CONCLUSION: This study of an independent cohort of multiplex families confirms the previously reported linkage between pauciarticular JRA and the HLA-DR region that was identified using a different analytic method in a cohort of simplex families. Additionally, this study establishes evidence for linkage between polyarticular JRA and the HLA-DR region.     

Chlamydial associated syndrome of arthritis and eye involvement in young children.

The current classification of juvenile rheumatoid arthritis (JRA) consists of several distinct subsets. We describe 6 children (2 boys, 4 girls, mean age 3.7 years, range 2.0-4.9 years) with arthritis and eye involvement associated with infection with Chlamydia trachomatis. In some of the children, the clinical picture was similar to early onset pauciarticular JRA: onset within the first 4 years of life, predominance of girls, pauciarticular arthritis, subacute uveitis, and presence of antinuclear antibodies. Joint involvement was pauciarticular in 4 patients and polyarticular in 2. Two patients had clinical symptoms of Reiter's disease. Further investigations of this post chlamydial associated syndrome should be performed to establish appropriate diagnostic, therapeutic and prognostic measures.     

Polymorphism in the MHC-encoded LMP7 gene: association with JRA without functional significance for immunoproteasome assembly.

OBJECTIVE: To determine if a polymorphism in the immunoproteasome subunit LMP7 was associated with juvenile rheumatoid arthritis (JRA) and had functional significance. METHODS: The frequency of LMP7QQ+ vs QQ- (QK and KK genotypes) among 207 patients with JRA and 50 controls was determined. JRA subtypes were pauciarticular (53%), polyarticular (33%), and systemic (14%). Onset was before age 6 (early onset) in 60% of patients. The functional significance of the LMP7 polymorphism was determined by comparing incorporation of LMP7Q vs LMP7K into proteasomes. RESULTS: There was an increased frequency of LMP7QQ in patients vs controls (73 vs 56%; p = 0.016), mainly due to the pauciarticular and systemic JRA subtypes (p = 0.037), and more pronounced in early onset disease (77 vs 56%; p = 0.006). The association persisted with stratification for HLA-DR5(11) and -DPB 1 *0201 (p = 0.002 and 0.013). We found no difference in the relative incorporation of LMP7Q and LMP7K into proteasomes. CONCLUSIONS: These results support an association between LMP7QQ homozygosity and JRA, particularly early onset disease. The difference persists with stratification, at least for DR5(11) and DPB1*0201, suggesting that this effect is unlikely to be due to linkage disequilibrium with HLA alleles known to be associated with early onset pauciarticular JRA. Importantly, as there does not appear to be functional significance associated with the LMP7 polymorphism, this may be a marker for another as yet unidentified susceptibility locus.     

Differences in the profiles of circulating levels of soluble tumor necrosis factor receptors and interleukin 1 receptor antagonist reflect the heterogeneity of the subgroups of juvenile rheumatoid arthritis

OBJECTIVE: To determine whether levels of soluble tumor necrosis factor receptor 55 (sTNFR55), sTNFR75, and interleukin 1 receptor antagonist (IL-1Ra) can differentiate different subtypes of juvenile rheumatoid arthritis (JRA), and to determine if the levels of these proteins correlate with disease activity. METHODS: Serum sTNFR (55 and 75) and IL-1Ra levels were measured by ELISA in 34 patients with JRA and these values were correlated with disease subtype and activity. RESULTS: Serum sTNFR55 levels were significantly elevated in patients with systemic onset JRA (SoJRA) (mean +/- 2 SD, 2.9 +/- 1.8 ng/ml) (p < or = 0.05) compared to rheumatoid factor positive (RF+) polyarticular JRA (2.1 +/- 0.6), RF-polyarticular JRA (1.5 +/- 0.6), and pauciarticular JRA (1.4 +/- 0.4). There was a trend for elevation of sTNFR75 levels in patients with SoJRA compared to other subtypes (p = 0.08). More patients had elevated levels of sTNFR75 than sTNFR55 (15 vs 7). This was true for all subsets (SoJRA 7 vs 5; polyarticular JRA 4 vs 2; and pauciarticular JRA 4 vs 0). In contrast to sTNFR, IL-1Ra levels were significantly elevated in RF+ polyarticular JRA compared to the other subgroups (p < or = 0.001). We found statistically significant Pearson correlations between (1) sTNFR75 and hemoglobin concentration: and (2) IL-1Ra and number of active joints and number of joints with effusions. CONCLUSION: The increased serum level of sTNF receptors in SoJRA suggests that TNF is likely more important than IL-1 in systemic inflammation and in particular in SoJRA. Conversely, IL-1 is likely more important in the inflammatory arthritis of JRA and in particular in the pathogenesis of RF+ polyarticular JRA. Our results suggest that cytokines have differing roles in JRA subtypes and likely reflect JRA subtype heterogeneity.