IgA and IgM rheumatoid factors as markers of later erosive changes in rheumatoid arthritis (RA)

The prognostic value of IgA anti-citrullinated protein antibodies and rheumatoid factor in an early arthritis population with a treat-to-target approach

The mucosal origin hypothesis of rheumatoid arthritis has renewed the interest in IgA autoantibodies, but their added value over IgG anti-citrullinated protein antibody (ACPA) and IgM rheumatoid factor (RF) for modern treatment outcomes remains unknown. We aimed to investigate the prognostic value of IgA-ACPA and IgA-RF for treatment outcomes in an early arthritis population. IgA-ACPA/RF isotypes were measured in baseline sera from 480 inflammatory arthritis (IA) patients, who were included in the treatment in the Rotterdam Early Arthritis Cohort trial (tREACH). The tREACH trial was a multicentre, stratified, single-blinded trial with a treat-to-target approach. The prognostic value of IgA-ACPA/RF was determined by evaluating differences in (1) quick-attained (< 6 months after diagnosis) and persistent remission rates, (2) DMARD-free remission and (3) biological use between IA patients with and without IgA-ACPA/RF over 3 years of follow-up. IgA-ACPA was present in 23% of patients and overlapped with IgG-ACPA positivity in 94%. Similarly, IgA-RF overlapped with IgM-RF in 90% of patients. IgA-ACPA positivity was associated with lower DFR rates and more biological use, but this effect was largely mediated by the presence of IgG-ACPA, since this effect disappeared after stratification for IgG-ACPA (HR 0.6, 95%CI 0.2-1.6 for DFR). No differences were observed in 'quick-attained and persistent remission' rates and for IgA-RF. Their seems to be no additional value of IgA-ACPA and IgA-RF for modern, long-term clinical outcomes. The effects of IgA-ACPA seen in our study are largely mediated by the presence of IgG-ACPA. Based on these results, there is no rationale for measuring these isotypes in daily practice.

Occurrence of anti-CCP2 and RF isotypes and their relation to age and disease severity among Sudanese patients with rheumatoid arthritis

OBJECTIVE

Anti-cyclic citrullinated peptide 2 antibodies (anti-CCP2) and rheumatoid factor (RF) in rheumatoid arthritis (RA) has been extensively assessed in industrialized countries. We investigated the diagnostic and prognostic impact of anti-CCP2 and RF isotypes in a Sudanese cross-sectional RA cohort.

METHODS

Consecutive RA patients (n = 281) diagnosed according to the 1987 ACR criteria were included 2008-2010. Anti-CCP2 and RF isotypes (IgA, IgM, and IgG) were measured by enzyme immunoassay in 262 patients, with reference intervals aligned to the same diagnostic specificity as for anti-CCP2 (97.6%) using national controls.

RESULTS

IgA RF was the predominant RA-associated autoantibody (56%), followed by IgM RF and anti-CCP2 (both 52%) and IgG RF (49%). In receiver operator characteristic analysis, IgA RF also showed the largest area under the curve. Patients with IgG RF were younger and had 8 years lower median age of disease onset compared to antibody negative patients (p < 0.0001). IgG RF was the only marker associated with a high number of involved joints (p = 0.028), and together with anti-CCP2 were the strongest markers for finger deformities (p = 0.016 and p = 0.012), respectively. No statistical differences were found for disease duration, ESR and Hb levels, and occurrence of erosions/osteopenia for any of the investigated autoantibodies.

CONCLUSION

Whereas IgA RF showed the best diagnostic performance, IgG RF associated with low age of RA onset, high number of involved joints, and finger deformities. These findings indicate that RA-associated antibodies other than conventional IgM RF and anti-CCP2 might be informative in non-Caucasian RA populations.

Diagnostic and clinical value of anti-cyclic citrullinated peptide antibodies compared with rheumatoid factor isotypes in rheumatoid arthritis

OBJECTIVE

To assess the additional diagnostic and clinical value of the second test generation of anti-cyclic citrullinated peptide antibodies (CCP2) compared with rheumatoid factor isotypes (IgG-RF, IgA-RF, IgM-RF) in patients with rheumatoid arthritis.

METHODS

This was a prospective study on 715 patients: rheumatoid arthritis (n = 295), degenerative or other inflammatory joint disease (n = 163), connective tissue disease or vasculitis (n = 103), and healthy controls (n = 154). Sera from each subject were tested for CCP2 and RF isotypes by enzyme linked immunosorbent assay (ELISA). Agreement with clinical indices such as disease activity, joint destruction, disease duration, and other laboratory tests was assessed. Sensitivity and specificity of the tests were evaluated taking the clinical diagnosis as the gold standard.

RESULTS

Highest sensitivity was found for IgM-RF (66.4%) and CCP (64.4%). Highest specificity was achieved by CCP (97.1%) and IgG-RF (91.0%). In rheumatoid patients with high disease activity or severe joint damage, CCP was more often present (81.4% and 83.6%) than all RF isotypes. Of special diagnostic value was the detection of positive CCP in 34.5% of all patients with rheumatoid arthritis when all measured RF isotypes (IgG-RF, IgA-RF, and IgM-RF) were negative.

CONCLUSIONS

As a screening method for rheumatoid arthritis the IgM-RF and the CCP assays are superior to other RF isotypes. Positivity in the highly specific CCP ELISA supports the diagnosis of rheumatoid arthritis. CCP proved to be a powerful diagnostic tool, especially in ambiguous cases or RF negative patients with rheumatoid arthritis.

Rheumatoid factor measured by fluoroimmunoassay: a responsive measure of rheumatoid arthritis disease activity that is associated with joint damage

OBJECTIVES

To determine whether rheumatoid factors (RFs), measured as continuous variables by time resolved fluoroimmunoassay, reflect disease activity in rheumatoid arthritis (RA). Further, to study the association of RFs and other disease activity parameters with radiological joint damage, especially in individual patients.

METHODS

In active, early RA, IgM and IgA RFs, as well as erythrocyte sedimentation rate (ESR), C reactive protein (CRP), tender joint score, and swollen joint score were assessed regularly. At the study start and at 56 and 80 weeks, radiographs of hands and feet were assessed by the Sharp score (van der Heijde modification). Associations between RFs and disease activity parameters were studied. In addition, associations between radiographic damage and disease activity parameters (baseline and time integrated) were analysed by non-parametric tests and multiple regression analysis. The relation between time integrated disease activity parameters and radiological damage in individual patients was analysed and visualised.

RESULTS

155 patients were included. RF levels were strongly associated with the disease activity parameters (especially ESR and CRP) and with each other. All disease activity parameters, at baseline as well as time integrated parameters, were associated with (the progression of) radiographic damage. Moreover, in individual patients, a linear relationship between time integrated disease activity parameters and progression of radiological damage was seen.

CONCLUSION

RFs, measured as continuous variables, can be considered as disease activity parameters in patients with RA. The level of RF at baseline and the exposure to RF over time is associated with radiological damage. In individual patients, there is a constant relation between disease activity and radiological damage.

Functional analysis of rheumatoid factor-producing B cells from the synovial fluid of rheumatoid arthritis patients

OBJECTIVE

To understand the regulation of rheumatoid factor (RF) production in rheumatoid arthritis (RA), we studied IgM-RF production by B cells isolated from the synovial fluid (SF).

METHODS

Highly purified SF and peripheral blood (PB) B cells were isolated by negative selection in a fluorescence-activated cell sorter (FACS) and then cultured with either L cells, CD40 ligand (CD40L)-transfected L cells, or type B synoviocytes in the presence or absence of interleukin-2 (IL-2), IL-4, or IL-10. Total IgM and IgM-RF were detected after 14 days by enzyme-linked immunosorbent assay. Enzyme-linked immunospot assays were performed to detect cells that spontaneously produced immunoglobulin. SF B cells were also phenotypically characterized by FACS analysis.

RESULTS

Terminally differentiated CD20-,CD38+ synovial plasma cells (PC) present in the SF of RA patients secreted IgM-RF in the absence of a stimulus. IgM-RF production markedly increased when SF B cells were cultured in the presence of type B RA synoviocytes together with IL-10, but independently of CD40-CD40L interaction. Although CD20-,CD38+ PC could also be demonstrated in SF B cells from patients with other forms of arthritis, IgM-RF production was restricted to the SF B cell cultures of patients with seropositive RA. The frequency of IgM-RF-producing cells among IgM-producing PC in patients with seropositive RA was estimated to be as much as 50%.

CONCLUSION

These data demonstrate that terminally differentiated CD20-,CD38+ IgM-RF-producing B cells are specifically present in the inflamed joints of patients with seropositive RA. There is evidence that the local environment in the rheumatoid joint favors RF production. The relatively high frequency of IgM-RF PC in the SF B cell population provides evidence of a dominant RA-specific antigen-driven response in the development of the synovial PC repertoire.

Diagnostic and prognostic characteristics of the enzyme linked immunosorbent rheumatoid factor assays in rheumatoid arthritis

OBJECTIVE

To determine the diagnostic and prognostic test qualities of the enzyme linked immunosorbent assays (ELISA) for rheumatoid factor isotypes in rheumatoid arthritis (RA), and to compare them with the latex fixation test.

METHODS

Rheumatoid factor tests were performed in 1988 consecutive new rheumatology outpatients within two months after their first visit to the outpatient clinic of the Department of Rheumatology of Leiden University hospital. The sensitivity, specificity, accuracy, and predictive values of the tests in discriminating RA from non-rheumatoid arthritis and erosive from non-erosive disease after two years of follow up were determined and presented as receiver operating characteristic curves and post-test probability curves.

RESULTS

The sensitivity of the ELISA for IgG, IgA, and IgM rheumatoid factor for RA versus all controls at optimal cut off titres was 72%, 44%, and 69%, respectively; the specificity was 52%, 84%, and 86%. For the latex fixation test the sensitivity was 66% and the specificity 91%. The post-test probability of RA, at a clinical prevalence rate of 12%, given a positive test result in the ELISAs for IgG, IgA, and IgM rheumatoid factor and the latex fixation test, was 17%, 27%, 40%, and 49%, respectively; with negative test results the probability was 7%, 8%, 5%, and 5%, respectively. The specificity of all tests in discriminating erosive from non-erosive RA at two years was low: 41%, 44%, 47%, and 58% for the ELISAs for IgG, IgA, and IgM rheumatoid factor and the latex fixation test, respectively.

CONCLUSION

The ELISAs for IgG and IgA rheumatoid factor are of no significance in diagnosing RA and in the prediction of erosive disease. The ELISA for IgM rheumatoid factor is a reasonable alternative for the latex fixation test when age and gender are taken in to consideration. The specificity of all rheumatoid factor tests in discriminating erosive from non-erosive RA is low.

Associations of IgA and IgA-rheumatoid factor with disease features in patients with rheumatoid arthritis

In previous studies we have shown that levels of IgM-rheumatoid factor (RF) in plasma and peripheral blood mononuclear cell supernatants are correlated with disease activity and response to second-line therapy in patients with rheumatoid arthritis (RA). The present studies were designed to examine whether IgA-RF levels are also correlated with clinical features of this disease. Two groups of RA patients were studied. Group I consisted of 87 patients in whom extensive clinical data had been collected. Group II included nine patients beginning treatment with gold or methotrexate who were studied during the first year of therapy. Measurement of IgM, IgA, IgM-RF and IgA-RF in culture supernatants and plasma was done by an ELISA method. These data were examined for correlations with clinical and laboratory features. Levels of IgA-RF in supernatants and plasma were found not to be correlated with disease features in the cross-sectional analysis of Group I patients, while IgM-RF and total IgA levels did show significant clinical correlation. Treatment of Group II patients with gold or methotrexate was associated with significant decreases in plasma levels of total IgA and IgM-RF as well as a small but statistically significant decrease in plasma IgA-RF. Plasma levels of total IgM were not altered during therapy. These findings suggest that production of IgA but not IgA-RF is correlated with disease status in patients with RA.

Clinical significance of rheumatoid factors in early rheumatoid arthritis: results of a follow up study

Serum rheumatoid factors (RF) were measured yearly in 135 women with rheumatoid arthritis by the Waaler-Rose and latex fixation tests and IgM, IgA, and IgG RF were measured by enzyme linked immunosorbent assays (ELISAs). The patients were followed up from an early phase of the disease for a mean duration of six years. Patients with a persistently positive RF test, irrespective of the type of test used, had more radiological abnormalities, more disease activity, worse functional ability, more extra-articular manifestations, and needed more treatment with second line drugs than patients with persistently negative or variably positive and negative test results during the follow up. Increased RF levels, especially a high level of IgA RF within three years of the onset of symptoms, was prognostic for a more severe disease outcome six years after the onset of symptoms.

Population study of the importance of rheumatoid factor isotypes in adults

Blood samples collected from 13,858 randomly selected subjects participating in a health survey in Iceland from 1974 to 1983 were tested for rheumatoid factor. Samples that were positive in a sensitive RF screening test were analysed further by the Rose-Waaler technique and an isotype specific enzyme linked immunosorbent assay (ELISA). In 1987 the 173 available participants who were RF positive and 156 matched RF negative controls were evaluated clinically for rheumatoid diseases. RF levels and isotype patterns were more persistent in the patients with rheumatoid arthritis (RA) than in RF positive subjects who did not have overt RA. The prevalence of RA was only 19% in the participants who were RF positive in 1987. Forty per cent of the participants who had a persistent (four to 13 years) increase of IgA RF combined with either IgM or IgG RF were diagnosed as having RA. A positive correlation was found between RF levels and various manifestations of RA. This association was stronger for the IgA and IgG RF isotypes than for IgM RF. Excluding RF positivity as a diagnostic parameter, RA was diagnosed in 33 of the participants and 20 (61%) of these patients had increased levels of IgM and IgA RF. Patients with RA with bone erosions in their hands had higher levels of IgA RF than patients without erosions, but an association was not found between bone erosions and other RF isotypes. None of the RF negative participants who were symptom free when the original blood sample was taken developed RA during the four to 13 year follow up period. In contrast, five symptom free RF positive participants developed RA during this period. These five patients had all had increased levels of at least two RF isotypes before the onset of their symptoms. It is concluded that the IgA and IgG RF isotypes have a closer association with the clinical parameters of RA than IgM RF. Furthermore, increases in RF can precede clinical manifestations of RA and this applies in particular to the IgA and IgG RF isotypes.

HLA typing and seropositivity in Finnish and in Polish patients with rheumatoid arthritis and amyloidosis

We determined HLA-A, -B, -C and -DR antigens in 83 patients with rheumatoid arthritis (RA) and reactive secondary amyloidosis (RSA), 60 in Finland and 23 in Poland, and compared the results with control RA patients and blood donors. There were no significant differences in the frequencies of HLA between the RA patients with and those without RSA in either Finland or Poland, and no significant differences between the Finnish and Polish patients with RSA. All the RSA patients from Finland and 70% of the RSA patients from Poland were seropositive. In the development of RSA, the prolonged period of inflammatory stimuli may play a more important role than genetic factors.

Hidden psoriatic arthritis in seronegative oligoarthritis: a 14-year follow-up study

Out of a cohort of 64 patients with seronegative oligoarthritis (SO), 8 patients with HLA-B13, 5 with Bw16 and 3 with HLA-B17 were invited to participate in a 14-year check-up. Thirteen patients showed some features of psoriatic arthritis, including 5 with suspected skin or nail disease, 5 with a family history of psoriasis, 3 with DIP joint affliction, and 2 with aortic valve insufficiency. It is concluded that a quarter of the patients with SO may have hidden psoriatic arthritis.