Correlation between rheumatoid factor and IL-6 activity in synovial fluids from patients with rheumatoid arthritis

Synovial fluids (SF) and sera (S) from patients with rheumatoid arthritis (RA) were examined for IgM, IgM-rheumatoid factor (IgM-RF), albumin and interleukin-6 (IL-6) activity. The quotient of SF/S IgM-RF was elevated compared with that of SF/S albumin in 7 patients with seropositive RA, although the quotient of SF/S IgM was lower than that of SF/S albumin. SF IL-6 activity was much higher than serum IL-6 activity in all the 7 RA patients. In synovial fluids from 22 seropositive RA patients, SF IL-6 activity was significantly correlated with the SF IgM-RF, IgG-RF and IgA- less than RF, but not with SF IgM, IgG or IgA. Moreover, SF IgM-RF as well as SF IL-6 activity was significantly correlated with the Westergren erythrocyte sedimentation rate (ESR) or the Lansbury articular index. These results indicate that IL-6 and RF might be produced within the rheumatoid joints as a result of abnormal immune system activation, which is associated with the disease activity of RA. Three of the 4 seronegative RA patients, however, showed high SF IL-6 without detectable levels of SF IgM-RF, indicating that IL-6 alone is not sufficient for IgM-RF production.     

Enzyme immunoassay of complement-binding rheumatoid factors

Summary We describe an enzyme immunoassay for the determination of complement-binding rheumatoid factors. Polystyrene tubes are coated with heat aggregated human IgG. The rheumatoid factors (RFs) of patients heat inactivated sera are allowed to bind to aggregated IgG and thereafter saturated with fresh human complement. The amount of C 3 complement bound is measured by indirect enzyme immunoassay. The levels of complement binding RFs were measured in 30 patients with seropositive rheumatoid arthritis (RA), in 19 patients with systemic lupus erythematosus (SLE), and in 30 healthy control subjects. Compared to the controls high levels of complement-binding RFs were found both in RA and in SLE (P<0.0005). The mean level of the complement binding RFs was higher (P<0.05) in active than in inactive SLE. Even though the 19 S IgM RF bound complement, in RA no correlation was found between the level of complement binding RFs and Waaler-Rose titre, but the level of complement binding RF correlated with the levels of nonagglutinating IgM RF (r=0.56, P<0.01) and IgG RF (r=0.70, P<0.001) that were obtained by enzyme immunoassay.     

Low molecular weight IgM in rheumatoid arthritis and other rheumatic diseases

Low molecular weight (LMW) IgM was measured in the serum and synovial fluid of patients with rheumatoid arthritis (RA) and other rheumatic diseases. High levels were seen in RA, particularly in rheumatoid vasculitis and Felty's syndrome, and significant correlations occurred between LMW IgM and the rheumatoid factor (RF) level and other indices that reflected active or severe disease. LMW IgM-RF, measured by radio-immunoassay in those column fractions containing LMW IgM, correlated significantly with LMW IgM (P < 0.005); preliminary experiments suggested that in some sera, a considerable proportion of the LMW IgM consisted of LMW IgM-RF. We conclude that LMW IgM and LMW IgM-RF may have important implications in the immunopathogenesis of RA and other rheumatic diseases.     

Elevation of a tumor associated antigen CA 19-9 levels in patients with rheumatic diseases

We investigated the incidence and characteristics of an elevated tumor associated antigen CA 19-9 in patients with rheumatic diseases. Serum concentration of CA 19-9 was increased in 13 of 39 patients (33.3%) with definite or classical rheumatoid arthritis (RA), in 6 of 19 patients (31.6%) with systemic lupus erythematosus (SLE), in 3 of 9 patients (33.3%) with progressive systemic sclerosis (PSS) and in 9 of the other 35 patients (25.7%). Malignant neoplasm was not detected in any of the patients with rheumatic diseases. Pretreatment of mouse serum with patients' sera did not reduce the measured CA 19-9 values obtained by the conventional assay. The CA 19-9 antigen found in sera from patients with RA was present in a non-IgG fraction, and had the same molecular weight as that in one patient with pancreatic cancer, as determined by gel filtration. These results demonstrated that serum CA 19-9 levels were increased in some patients with rheumatic diseases.     

IgG and IgM rheumatoid factor synthesis in rheumatoid synovial membrane cell cultures

The detection of rheumatoid factors (RFs) in synovial membranes and fluids of patients with rheumatoid arthritis (RA) has suggested that local production of these antiimmunoglobulin autoantibodies may have a role in the pathogenesis of synovitis. To quantitate RF synthesis in the rheumatoid synovial membrane, 12 synovial specimens were obtained from patients with seropositive RA, 5 from patients with seronegative RA, and 6 from patients with other arthritides. Single cell suspensions were cultured, and supernatants were analyzed for IgG, IgM, IgG-RF, and IgM-RF by solid-phase radioimmunoassays. IgM-RF was detected in all of the 12 seropositive culture supernatants, and IgG-RF was detected in 8 of the 12. Addition of cycloheximide to the cultures resulted in a greater than or equal to 40% decreased in the amount of IgM-RF. A similar decrease in IgG-RF occurred in the 4 cultures in which the largest amounts of IgG-RF were detected. IgM-RF synthesis represented 7.3 +/- 0.7% (mean +/- SEM) of the total IgM produced, and IgG-RF represented 2.6 +/- 1.1% (mean +/- SEM) of the IgG synthesized in those cultures with detectable IgG-RF. Cultures of synovial membrane cells (SMC) from seronegative RA patients or patients with other arthritides did not contain detectable amounts of IgM-RF or IgG-RF. Selective synthesis of RF by seropositive synovium was suggested by the observation that the fractions of synthesized IgM with RF activity were greater in the SMC supernatants than in paired sera in all cases, and the fractions of IgG with RF activity were greater in the SMC supernatants of 3 of the 4 cases in which substantial amounts of IgG-RF were produced. Comparison of the percentages of newly synthesized IgM with RF activity in paired cultures of SMC and peripheral blood mononuclear cells similarly indicated selective synthesis of IgM-RF by the synovium. These results demonstrate active and selective synthesis of both IgG-RF and IgM-RF by seropositive SMC. However, RFs account for only a minor fraction of the total Ig produced.     

Suppression of rheumatoid factor production by methotrexate in patients with rheumatoid arthritis. Evidence for differential influences of therapy and clinical status on IgM and IgA rheumatoid factor expression

Suppression of rheumatoid factor (RF) production in rheumatoid arthritis (RA) has been variably attributed to the use of remittive agents per se or to clinical improvement associated with their use. There have been conflicting reports with regard to the influence of methotrexate (MTX) on serum RF levels in RA. We determined IgM-RF and IgA-RF levels in paired serum samples (obtained at study entry and completion) from RA patients enrolled in multicenter trials with the Cooperative Systematic Studies of Rheumatic Diseases program. After exclusion of the 14 IgM-RF-negative sera, there were samples from 30 MTX-treated patients and 52 placebo-treated patients. Changes in IgM-RF and IgA-RF levels were weakly associated with each other. Significant decreases in IgM-RF levels were observed in the MTX-treated patients, but not in the placebo group. These changes were most significant in the MTX-treated patients who improved clinically. There were significant decreases in IgA-RF levels at study completion among MTX-treated patients who had improved clinically and those who had not improved clinically, but not in the placebo group. The contributions of clinical improvement and MTX treatment to changes in serum IgM-RF and IgA-RF levels were examined using a logistic regression model. Changes in IgM-RF were strongly related to MTX treatment and, to a lesser extent, to clinical improvement; changes in IgA-RF were related only to MTX treatment. These results indicate that MTX treatment per se decreases both IgM-RF and IgA-RF levels, whereas clinical improvement correlates with decreased IgM-RF levels only.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rheumatoid factor and antibodies to cyclic citrullinated Peptide differentiate rheumatoid arthritis from undifferentiated polyarthritis in patients with early arthritis

OBJECTIVE: To study the diagnostic value of IgM rheumatoid factor (RF), IgA-RF, antibodies to cyclic citrullinated peptide (anti-CCP), and combinations of these antibodies, measured at baseline, to discriminate rheumatoid arthritis (RA) from undifferentiated polyarthritis (uPA) in patients with recent onset arthritis. METHODS: Patients with early arthritis with peripheral arthritis of 2 or more joints and symptom duration less than 3 years were clinically diagnosed as having RA or uPA by an experienced rheumatologist during the first year. Patients with bacterial, psoriatic, or crystal induced arthritis or spondyloarthropathy were excluded. Optimal cutoff values for serum IgM RF, IgA RF, and anti-CCP were deduced from receiver operating characteristics curves in order to predict the diagnosis of RA in early arthritis. RESULTS: A total of 379 patients (69% female, median age 57 yrs, range 17-86 yrs) were studied; 258 patients were clinically diagnosed as RA and 121 as uPA. Both IgM-RF > 40 IU/ml and anti-CCP > 50 AU/ml showed high specificity, but the sensitivity of these tests was low. In many RA patients the occurrence of IgM-RF and anti-CCP antibodies was independent. Thus the optimal criterion proved to be the combination of IgM-RF > 40 or anti-CCP > 50, which yielded sensitivity of 55.4% and specificity of 96.7%. CONCLUSION: The criterion IgM-RF > 40 or anti-CCP > 50 is able to predict the diagnosis of RA in early arthritis patients with high specificity and acceptable sensitivity. Anti-CCP testing combined with IgM-RF testing has additional value over IgM-RF testing alone in patients with early undifferentiated oligo and polyarthritis.     

QUANTITATIVE DETECTION OF CLASS-SPECIFIC RHEUMATOID FACTORS USING MOUSE MONOCLONAL ANTIBODIES AND THE BIOTIN/STREPTAVIDIN ENHANCEMENT SYSTEM

An enzyme-linked immunosorbent assay (ELISA) for the quantitativedetection of rheumatoid factors (RF) was developed using mousemonoclonal antibodies against human IgG, IgA and IgM togetherwith the biotin/streptavidin enhancement system. One hundredand eight patients with rheumatoid arthritis (RA) of whom 47had a positive serum latex agglutination assay, 100 healthycontrols and 95 diseased controls (25 systemic lupus erythematosus(SLE), 25 ankylosing spondylitis, 20 osteoarthritis and 25 bronchialasthma) were evaluated for the presence of IgG-, IgA- and IgM-RFby ELISA. Elevated levels of IgG-, IgA-, and IgM-RF could bedemonstrated in respectively 94%, 91% and 98% of serum samplesfrom RA patients with a positive latex test and in 72%, 69%and 8% of serum samples from RA patients with a negative latextest. In the latter patient group, increased levels of one ormore RF isotypes could be detected m 82% of the patients. Exceptfor the presence of IgG-RF in serum of 20% of the SLE patients,increased levels of RF isotypes were present in less than 5%of the diseased controls. Highly significant correlations werefound between serum IgM-RF levels as detected by ELISA and thoseof the latex and the Rose-Waaler agglutination assays. Positivecorrelations were also found between the serum levels of thethree RF isotypes investigated and between the levels of RFisotypes as measured in serum and synovial fluid of the samepatient. Compared to agglutination assays, the ELISA for thequantitative detection of RF isotypes is a more reproducibleand sensitive test which avoids some of the problems encounteredin earlier ELISA methods. KEY WORDS: Rheumatoid factor, ELISA, Rheumatoid arthritis     

Cathepsin D Agglutinators in Rheumatoid Arthritis

The incidence and titer of cathepsin D agglutinators (CDA) were significantly higher in seropositive rheumatoid arthritis (RA) sera than in the sera of healthy blood donors or of patients with other rheumatic diseases, including seronegative RA. A significant elevation was also found in synovial fluid (SF) samples from seropositive RA patients. CDA in the SF tended to be increased when compared with the corresponding serum. The levels of CDA correlated positively with those of rheumatoid factors (RF) when the latter were determined with IgG anti-CD Ripley-coated erythrocytes, but not when they were determined by the Waaler-Rose or latex tests. The increased CDA titers do not seem to be the result of significant amounts of IgM agglutinators or of the presence of IgM-RF. These findings suggest the existence of a link between the formation of RF and CDA, but the nature of this link cannot be fully explained.     

IgM,IgA and IgG rheumatoid factors in patients with rheumatoid arthritis and normal donors

Summary IgM, IgA, and IgG Rheumatoid Factors (RF) were measured by ELISA assay in serum from 26 patients with definite rheumatoid arthritis (RA) and 11 normal controls. IgM-RF was assayed by ELISA, radioimmunoassay,and also by the standard latex fixation test in all sera from RA patients. In patients with RA quantitative amounts of IgM, IgA, and IgG-RF as estimated by ELISA were highly correlated. Significant correlations were found between a physician's rating of disease activity and IgG-RF (r=0.44; p<.02) and IgA-RF (r=0.38; p=.06 but not for IgM-RF as measured in any of the three assays.During the course of this work F.S. was supported by a NATO fellowship from the Consiglio Nazionale delle Ricerche, Roma, Italy.     

Cathepsin D agglutinators in rheumatoid arthritis. I. Increased CDA titers in serum and synovial fluid of patients with seropositive RA.

The incidence and titer of cathepsin D agglutinators (CDA) were significantly higher in seropositive rheumatoid arthritis (RA) sera than in the sera of healthy blood donors or of patients with other rheumatic diseases, including seronegative RA. A significant elevation was also found in synovial fluid (SF) samples from seropositive RA patients. CDA in the SF tended to be increased when compared with the corresponding serum. The levels of CDA correlated positively with those of rheumatoid factors (RF) when the latter were determined with IgG anti-CD Ripley-coated erythrocytes, but not when they were determined by the Waaler-Rose or latex tests. The increased CDA titers do not seem to be the result of significant amounts of IgM agglutinators or of the presence of IgM-RF. These findings suggest the existence of a link between the formation of RF and CDA, but the nature of this link cannot be fully explained.     

Defensins- and cathepsin G-ANCA in systemic lupus erythematosus

In this study, we examined the content of antineutrophil cytoplasmic antibodies (ANCA) against defensins and cathepsin G in sera from systemic lupus erythematosus (SLE) patients and their significance in estimating the activity of SLE. Defensins- and cathepsin G-ANCA in sera from 28 patients with SLE, eight patients with rheumatoid arthritis (RA) and eight patients with microscopic polyangitis (mPA) were measured by ELISA. Significantly increased defensins- and cathepsin G-ANCA were found in sera of patients with SLE and mPA when compared with the value of normal controls. Though significantly higher defensins- and cathepsin G-ANCA were detected in both active and inactive SLE patients, the value in active SLE patients was significantly higher than inactive SLE patients. After the therapy with high dose of prednisolone, the serum level of defensins- and cathepsin G-ANCA was decreased, and this decrease was sustained for at least 16 weeks. This study suggests that defensins- and cathepsin G-ANCA may serve as useful markers of the disease activity of SLE.     

IgM rheumatoid factor plaque-forming cells in juvenile rheumatoid arthritis

Using a direct, plaque-forming cell (PFC) assay with sensitized sheep erythrocytes, lymphocytes that secrete IgM rheumatoid factors (RF) have been detected in the peripheral blood of patients with juvenile rheumatoid arthritis. Of 15 juvenile rheumatoid arthritis patients tested, 8 were seropositive and 7 were seronegative, but 6 of the seronegative patients had hidden 19S IgM-RF. Ten patients (5 seropositive and 5 with hidden 19S IgM-RF) demonstrated RF-PFC in their peripheral blood (range 15 to greater than 200 RF-PFC/10(6) mononuclear cells). Of 11 patients who had active disease, 10 had RF-PFC, and the 4 patients who had inactive disease had no PFC in their peripheral blood. HLA typing of all 15 patients revealed no correlation between the presence of RF-PFC and HLA type.     

Immunoglobulin class of rheumatoid factors detected by enzyme-linked immunosorbent assay

Summary The immunoglobulin class of rheumatoid factor (RF) in sera and synovial fluids of patients with rheumatic diseases was measured by a solid-phase enzyme immunoassay. IgG-RF was frequently found in seronegative sera as well as in seropositive sera of rheumatic patients. Titers of IgG-RF were higher in the active phase than in the inactive phase of SLE and showed a correlation to the levels of hypocomplementemia and circulating immune complexes in SLE sera. Titers of IgA-RF were likewise higher in the active-phase of SLE with a correlation to titers of circulating immune complexes. IgA-RF was also found frequently in sera of patients with Sjögren's syndrome.     

可溶性细胞间黏附分子-1和可溶性选择素E在自身免疫性风湿病中的表达

目的了解自身免疫性风湿病患者血清中两种可溶性黏附分子(sAM)——可溶性细胞间黏附分子-1(sICAM-1)和可溶性选择素E(sE-selectin)的水平,并揭示两种sAM与临床病情的关系。方法采用酶联免疫吸附试验(ELISA)检测三种自身免疫性风湿病系统性红斑狼疮(SLE)、类风湿关节炎(RA)、多发性肌炎/皮肌炎(PM/DM)患者,30例非自身免疫性风湿病患者及20名健康对照血清中sICAM-1、sE-selectin的含量,并分析两种sAM与临床资料、实验室检测指标的相关性。结果所测自身免疫性风湿病患者(包括3个组)血清中sICAM-1、sE-selectin水平较非自身免疫性风湿病及正常对照组明显增高(P<0.05)。RA组患者血清中sICAM-1与类风湿因子(RF)呈正相关。PM/DM组患者血清sE-selectin水平与肌酸激酶(CK)值呈正相关。结论本研究结果表明,sICAM-1和sE-selectin参与了自身免疫性风湿病的发病过程。异常升高的sICAM-1、sE-selectin水平可反映某些类型的自身免疫性风湿病(RA、PM/DM)的活动程度。     

Down-regulation of immunoglobulin and IgM-rheumatoid factor synthesis by oral treatment of rheumatoid arthritis patients with a nonsteroidal antiinflammatory drug

Summary We examined the effect of treatment with piroxicam, a nonsteroidal antiinflammatory drug (NSAID), on immunoglobulin (Ig) and IgM-rheumatoid factor (IgM-RF) synthesis in vitro by lymphocytes of patients with rheumatoid arthritis (RA). Oral treatment with piroxicam induced a progressive decrease of spontaneous IgM-RF production by unstimulated lymphocyte cultures during 12 weeks of observation. Also, pokeweed mitogen (PWM)-driven Ig synthesis was significantly diminished and the effect on total IgM production was sustained until the end of the study. This modulation of humoral responses is consistent with the drop in RF sera level. In addition, we also showed that treatment with NSAIDs can decrease RF levels in the synovial space. NSAIDs may have a long-term beneficial effect in patients with RA due to their modulatory role of lymphocyte responses.     

Soluble CD154 in rheumatoid arthritis: elevated plasma levels in cases with vasculitis.

OBJECTIVE: To determine the levels of soluble CD154 (sCD154) in the plasma of patients with rheumatoid arthritis (RA) and rheumatoid vasculitis (RV). and to examine the relationship between the levels of sCD154 in plasma and the clinical variables. METHODS: Levels of sCD154 were quantified in 39 plasma samples from patients with RA, including 9 patients who were also diagnosed with RV, and compared with those of 20 healthy subjects. An ELISA was established and specificity of the ELISA was tested by control ELISA using isotype-matched IgG and preabsorption assay. The titers of IgM and IgG rheumatoid factor (IgM-RF, IgG-RF) for each patient were determined simultaneously, and values of other laboratory variables were also determined. RESULTS: Levels of sCD 154 in plasma were higher in patients with RA than in the healthy subjects (p < 0.02). Compared with RA patients without vasculitis, patients with RV had significantly higher levels of sCD154 in their plasma (p < 0.001). Control ELISA and absorption assay of sCD154 indicated that our ELISA system was capable of measuring plasma sCD154 in RA patients. Levels of sCD154 in RA plasma correlated significantly with both IgM-RF and IgG-RF titers (r = 0.64 and 0.61, respectively, both p < 0.001). The levels of sCD154 decreased after commencement of treatment for vasculitis in cases with RV. CONCLUSION: We identified the presence of sCD154 in RA plasma, with especially high levels in cases with vasculitis. Correlation between sCD154 and RF titers indicates the CD154-CD40 pathway is likely related to pathogenic RF production.     

Human parvovirus B19 infection in patients with systemic lupus erythematosus

OBJECTIVE: The clinical significance of the presence of B19 DNA in patients with SLE was studied. METHODS: Sera from 72 patients with systemic lupus erythematosus (SLE), 23 patients with rheumatoid arthritis (RA), 18 patients with Sj?gren's syndrome (SS), eight patients with Raynaud's phenomenon (RP), five patients with primary biliary cirrhosis (PBC), five patients with polymyositis (PM), four patients with erythema infectiosum (EI) and 22 normal controls were examined for parvovirus B19 (B19) infection by serological assays, nested PCR and Southern blotting. RESULTS: Parvovirus B19 DNA was detected in 17 of 72 patients with SLE and in three of four patients with EI, but not in patients with other systemic rheumatic diseases. Of the 17 patients with B19 DNA, only one had IgG anti-B19 antibody and two had IgM anti-B19 antibodies, whereas IgG and IgM anti-B19 antibodies were detected in 27 (49.1%) and 21 (38.2%) of 55 SLE patients without B19 DNA respectively. All sera from the patients with EI contained both IgG and IgM anti-B19 antibodies. B19 DNA was found more commonly in sera from SLE patients without anti-B19 antibodies than in those with anti-B19 antibodies (P<0.05). CONCLUSIONS: B19 infection in patients with SLE may be due to lack of anti-B19 antibodies because of either the immunocompromised nature of the host or the use of immunosuppressive drugs. There was a higher prevalence of hypocomplementaemia and RP in patients with parvovirus B19 viraemia than in those without parvovirus B19 viraemia.     

Complement-activating properties of immune complexes are suppressed by IgM rheumatoid factor and enhanced by IgG rheumatoid factor

Summary The effect of rheumatoid factor (RF) on complement-activating capacity of aggregated IgG was investigated. The degree of complement activation induced by the addition of specific amounts of aggregated IgG to patients' sera and normal sera was demonstrated by the inhibition of hemolytic activity (%IHA). The %IHA was significantly lower in rheumatoid arthritis (RA) sera and higher in systemic lupus erythematosus (SLE) sera, compared with normal sera. There was a negative correlation between %IHA and IgMRF/IgGRF ratio in RA and SLE sera, and RA synovial fluid. The %IHA and IgGRF were positively correlated in RA sera. The IgMRF/IgGRF ratio was significantly lower in SLE sera than in RA sera and systemic sclerosis sera, and was significantly lower in RA synovial fluid than in osteoarthritis synovial fluid.Isolated RF, consisting of mostly IgMRF class, inhibited complement-activating properties of aggregated IgG, depending on the concentration of RF. Isolated RF was further purified by the fractionation using high pressure liquid chromatography, and IgGRF and IgMRF were obtained. IgMRF significantly suppressed the complement-activating capacity of aggregated IgG, whereas IgGRF promoted it. These observations suggest that IgMRF acts protectively, while IgGRF induces inflammation.Thus, the expression of the biological activity of RF with special reference to immune complex interaction mainly depends on the IgMRF/IgGRF ratio.     

Estimation of the relative avidity of 19S IgM rheumatoid factor secreted by rheumatoid synovial cells for human IgG subclasses

19S IgM rheumatoid factors (RF) may play an important role in sustaining inflammation in rheumatoid arthritis (RA). As yet, no unique antigenic specificity for RF in RA has been identified. Because the synovium is central to the pathogenic changes in RA, RF produced therein might be pathogenically more important than serum RF. Therefore, we examined the reactivity and relative avidity of 19S IgM-RF in serum and rheumatoid synovial cells (RSC) from 20 patients with seropositive RA. Reactivities were determined by competitive inhibition of serum RF hemolytic activity and RSC RF-plaque-forming cells (PFC) by added soluble antigen, i.e., monomeric human IgG subclasses. Estimation of relative avidities of RSC RF for human IgG subclasses was done by calculation of fractional RF expression in the RSC RF-PFC assay following inhibition by IgG subclasses. RSC RF had greatest reactivity with IgG3 and IgG1, some reactivity with IgG2, and the least reactivity with IgG4. Serum RF reacted most with IgG1 and IgG2, reacted some with IgG4, but reacted poorly with IgG3. The antigenic determinants with which RSC RF reacted were common to many IgG3 molecules. The highest relative avidity of RSC RF was for IgG3. These observations indicate a selective deficiency of serum RF compared with RSC RF and suggest an important pathogenic role for these qualitatively different RSC RF molecules for in situ RF immune complex-mediated inflammation in RA synovial tissue.