Rheumatoid factors in rheumatoid arthritis and vasculitis

Effectiveness and safety of rituximab in special types of rheumatoid arthritis

OBJECTIVES

To elucidate the efficacy and safety of rituximab in special types of rheumatoid arthritis.

METHODS

We retrospectively reviewed all patients with rheumatoid arthritis with lymphoproliferative disorder or vasculitis treated with rituximab between April 2010 and June 2022 at Keio University Hospital. We assessed the effectiveness of rituximab using the Disease Activity Score for 28 joints-erythrocyte sedimentation rate (DAS28-ESR), Clinical Disease Activity Index (CDAI), and safety of rituximab during the disease course. We also assessed the glucocorticoid-sparing effects of rituximab.

RESULTS

We included eight patients with a history of lymphoproliferative disorder and five patients with rheumatoid vasculitis. They were treated with rituximab without high-dose glucocorticoid. The mean DAS28-ESR and CDAI scores significantly improved 12 months after rituximab administration (DAS28-ESR, 4.7 vs. 2.7, p < .001; CDAI, 16.0 vs. 5.1, p = .006, respectively), and the dose of prednisolone was reduced from a mean of 7.4 mg/day to 4.0 mg/day at 12 months (p = .05) and 3.2 mg/day at the last visit (p = .04). During the mean follow-up period of 52 months, we recorded one recurrence of lymphoproliferative disorder (not B-cell type) in patients with a history of lymphoproliferative disorder and remarkable improvement of skin ulcers in patients with vasculitis.

CONCLUSION

B-cell depletion by rituximab may be a useful treatment option for patients with lymphoproliferative disorder and rheumatoid vasculitis.

The association of choroidal thickness with rheumatoid factor and anti-cyclic citrullinated peptide in rheumatoid arthritis

PURPOSE

To measure ocular vascular parameters in rheumatoid arthritis patients and compare with those of controls and to evaluate the association of rheumatoid factor and anti-cyclic citrullinated peptide antibody with the choroidal thickness.

METHODS

Superficial foveal vessel density, superficial and deep foveal avascular zone area, and subfoveal choroidal thickness were measured using the swept-source optical coherence tomography angiography. Multivariate linear regression was used to assess the correlation of subfoveal choroidal thickness with serological markers in patients with rheumatoid arthritis.

RESULTS

Choroidal thickness in patients was significantly thinner than that in healthy controls (278.87 ± 59.54 μm vs. 323.94 ± 98.02 μm, p = 0.03). Despite the weak positive correlations between rheumatoid factor/anti-cyclic citrullinated peptide and choroidal thickness, these relationships were not statistically significant (p > 0.05).

CONCLUSIONS

In patients with rheumatoid arthritis, subfoveal choroid was thinner than controls. There were similar correlations between choroidal thickness and rheumatoid factor and anti-cyclic citrullinated peptide antibody.

Antibody-dependent and -independent mechanisms of inflammatory arthritis

Inflammatory arthritis encompasses a set of common diseases characterized by immune-mediated attack on joint tissues. Most but not all affected patients manifest circulating autoantibodies. Decades of study in human and animal arthritis have identified key roles for autoantibodies in immune complexes and through direct modulation of articular biology. However, joint inflammation can arise because of pathogenic T cells and other pathways that are antibody-independent. Here we review the evidence for these parallel tracks, in animal models and in humans, to explore the range of mechanisms engaged in the pathophysiology of arthritis and to highlight opportunities for targeted therapeutic intervention.

Jejunal vasculitis in patient with rheumatoid arthritis: case report and literature review

A 57-year-old man with rheumatoid arthritis presented severe abdominal pain symptomatic of panperitonitis. Computer tomography findings were consistent with vasculitis on the jejunum. Confirmatory angiography was conducted. Since abdominal vasculitis in rheumatoid arthritis is very rare, early diagnosis and treatment should be done according to clinical manifestation. In this case, high-dose steroid treatment was applied based on clinical manifestation, laboratory findings, and radiologic finding. After therapy, clinical manifestation and flare-up arthritis diminished.

Power Doppler ultrasonography of symptomatic rheumatoid arthritis ankles revealed a positive association between tenosynovitis and rheumatoid factor

The aim of this study was to characterize the pathological conditions of symptomatic ankles in patients with rheumatoid arthritis (RA) using power Doppler sonography (PDS). We analyzed 17 consecutive ultrasonography (US) records of RA patients with symptomatic ankles who underwent B-mode ultrasonography (BUS) combined with PDS of their ankles in our department because of clinical need. Correlations between US findings and clinical and serological data were assessed. The diagnostic capabilities of BUS and PDS were also compared. Common US findings were talocrural synovitis (76%), subtalar synovitis (71%), and talonavicular synovitis (59%). Tenosynovitis around the ankle was detected in ten patients (59%), including several cases of tenosynovitis of tibialis posterior (41%) and tenosynovitis of peroneus longus and brevis (35%). Achilles tendon enthesitis was detected in six patients, and retrocalcaneal bursitis was detected in five. Compared with BUS, PDS offers demonstrably superior diagnostic capability for the detection of rheumatoid ankle diseases, especially subtalar joint synovitis and peroneal tenosynovitis. Rheumatoid factor (RF) levels were significantly higher in patients with tenosynovitis than in patients without tenosynovitis. PDS is an excellent modality for diagnosing both intra- and extracapsular synovitis in rheumatoid ankles. Using PDS, we found positive association between ankle tenosynovitis and RF levels in RA patients.

Bone mineral density in patients with recently diagnosed, active rheumatoid arthritis

OBJECTIVES

Osteoporosis is a well-known extra-articular phenomenon in patients with uncontrolled, long-standing rheumatoid arthritis (RA). In the present study, the extent of osteoporosis and reduced bone mineral density (BMD) and the disease-related and demographic factors that are associated with osteoporosis and reduced BMD were examined in patients with recently diagnosed, active RA.

METHODS

BMD of the total hip and the lumbar spine was measured using dual-energy x ray absorptiometry in 381 patients with recently diagnosed active RA, who had never been treated with DMARDs or corticosteroids. Osteoporosis was defined as a T score <or=-2.5 SD and reduced BMD as Z score <or=-1 SD. Multivariate logistic regression analyses were performed to detect associations of osteoporosis and reduced BMD with disease activity, functional disability, joint damage (Sharp-van der Heijde score) and demographic factors.

RESULTS

Osteoporosis and reduced BMD were found in the spine and/or the hip in 11% and 25%, respectively, of the patients. Longer symptom duration and presence of rheumatoid factor (RF) were the only RA-specific markers for osteoporosis and reduced BMD. Further, postmenopausal status in women, a low body mass index, familial osteoporosis, and, remarkably, male gender, were independently associated with osteoporosis and reduced BMD.

CONCLUSION

In patients with recently diagnosed active RA who had never been treated with DMARDs or corticosteroids, BMD seems to be well-preserved and predominantly related to demographic factors. Longer symptom duration and a positive RF, but not higher disease activity or more joint damage, were related to osteoporosis and reduced BMD.

Systemic rheumatoid vasculitis: a review

OBJECTIVES

To review the most recent information on the incidence, clinical course, pathology, pathogenesis, diagnosis, and treatment of rheumatoid vasculitis (RV), including the still scanty data on the use of biologics.

METHODS

PubMed and MEDLINE databases (1950-2006) were searched for the key words "vasculitis" and "rheumatoid arthritis"; and "rheumatoid arthritis" and "extra-articular manifestations." All relevant articles in English and French were reviewed. Additional words used in follow-up research include "anti-TNF," "rituximab," "IL-1 receptor antagonists," and "CTLA-4 Ig," all in conjunction with "vasculitis." Pertinent secondary references were also retrieved.

RESULTS

RV is an inflammatory condition of the small- and medium-sized vessels that affects a subset of patients with established rheumatoid arthritis (RA) (approximately 1 to approximately 5%). It has a vast array of clinical manifestations with a predilection for the skin (peripheral gangrene, deep cutaneous ulcers) and the peripheral nervous system (mononeuritis multiplex). Because of the lack of specific signs and symptoms, the diagnosis relies on the exclusion of other causes of similar lesions (diabetes, atherosclerosis, drug reactions, infection, neoplasias) and, ideally, on the histopathological demonstration of necrotizing vasculitis. Despite the availability of a host of promising new drugs for the treatment of RA, no clinical trials have tested their efficacy in RV; therefore, its management remains largely empirical.

CONCLUSIONS

Although RV has apparently been decreasing over the last 2 decades, possibly as a consequence of the more energetic approach to the management of RA currently used, it remains an important complication of RA that needs to be promptly recognized and treated.

Effects of rheumatoid factor isotypes on disease activity and severity in patients with rheumatoid arthritis: a comparative study

The value of rheumatoid factor (RF) isotypes for assessing rheumatoid arthritis (RA) remains debatable. In this study, we have examined the relationships between RF isotypes and disease activity and severity in RA patients. Sixty-two patients with RA, 48 women and 14 men, were studied. RF was measured by nephelometry (RF-N) and IgG-, IgA-, and IgM-RF isotypes were measured using enzyme-linked immunosorbent assay. Serum C-reactive protein and erythrocyte sedimentation rate were also determined. The patients were classified according to disease activity, joint damage, functional status, and presence of pulmonary involvement, rheumatoid nodule, and secondary Sjögren's syndrome. Although the patients with active disease had significantly higher IgA-RF and IgM-RF levels compared to inactive patients, IgA-RF and IgM-RF were not found to be independently associated with disease activity in multivariate analysis. In patients with severe joint damage, IgA-RF and RF-N were significantly higher than those of the other patients. Multiple regression analysis showed that IgA-RF was the unique variable independently associated to severe joint damage. The patients with class III and IV functional index had significantly higher IgM-RF, IgA-RF, and RF-N levels compared to the patients with class I and II functional index; however, RFs were not significantly associated with functional status in multivariate analysis. IgA-RF and IgM-RF were significantly associated with pulmonary involvement and rheumatoid nodule, respectively. No significant associations were found between RF isotypes and secondary Sjögren's syndrome. Our results suggest that the clinical usefulness of IgA and IgM isotypes is better than RF-N. Elevated IgA-RF may be a marker of erosive disease. The usefulness of RF isotypes for monitoring disease activity or functional status appears to be limited.

Early Rheumatoid Arthritis

The treatment of rheumatoid arthritis (RA) has changed dramatically in the past decade as advancements in the understanding of the pathobiology of the disease have led to novel therapeutic agents. The recognition that early diagnosis and treatment leads to improvements in morbidity and mortality has altered the therapeutic strategy such that early therapy is now considered the standard of care. This review focuses on the challenges in making the diagnosis of early RA, including a broad differential diagnosis for inflammatory polyarthritis, poor performance of the standard classification criteria, difficulty in clinical assessment of synovitis, absence of absolute laboratory tests, inability of conventional radiography to detect bony changes early, and barriers to rheumatology care. Additionally, the pathogenesis of RA is highlighted, with particular emphasis on cytokine biology as it relates to therapeutic regimens. Relevant clinical trials in early RA are reviewed and discussed, including trials of combination disease-modifying antirheumatic drugs and biological therapy. The role of induction therapy as a novel therapeutic approach is highlighted. The search for predictors of response is reviewed and the external validity of the trials is analysed. Finally, the trials in early RA therapy suggest that swift intervention with combinations of medications is required for patients with severe RA. However, further research is needed to determine which regimen is appropriate for the individual patient with RA.

Proteomic: New advances in the diagnosis of rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disease affecting the joints. A number of novel treatment modalities have been introduced over the past years, and rheumatologists are now attempting to institute optimal treatment in recent-onset arthritis. To facilitate diagnosis during the early stages of disease, when often not all clinical symptoms are manifest, a good serological marker is needed.

METHODS

Antibodies directed to citrullinated proteins provide this ability. The most sensitive assay for detecting these antibodies is the so-called anti-cyclic citrullinated peptide, second generation (CCP II) enzyme-linked immunosorbent assay (ELISA).

RESULTS

The diagnostic and prognostic potential of anti-CCP antibodies and the availability of a fully automated assay method lead us to conclude that the test is satisfactory for routine use as a serological marker of RA. In addition, we consider the potential of multiplex autoantibody assays, including miniaturized, high-throughput microarray technology, to improve diagnosis and prognostication in early onset arthritis patients.

Diagnostic strategy for the assessment of rheumatoid vasculitis

OBJECTIVE

To determine the clinical features associated with histologically proven rheumatoid vasculitis (HRV) and the additional diagnostic value of serological markers in an inception cohort of 81 patients with rheumatoid arthritis (RA) suspected of RV.

METHODS

The presence and number of recently developed extra-articular manifestations (EAMs) and a weighted EAM score, as well as the levels of serological markers, were compared between 31 patients with RA with histologically proven vasculitis and 50 patients with RA in whom vasculitis could not be documented histologically. The following markers were evaluated: circulating immune complexes, complement components C3 and C4, class-specific rheumatoid factors (IgM RF, IgG RF, IgA RF), antineutrophil cytoplasmic antibodies, antinuclear antibodies, antiendothelial antibodies, circulating intercellular adhesion molecule-1 and -3, circulating vascular cell adhesion molecule and E-selectin, cellular fibronectin, von Willebrand factor antigen, and C reactive protein. The diagnostic value of these markers, in addition to the clinical features, was evaluated with logistic regression analysis.

RESULTS

Peripheral neuropathy or purpura/petechiae, or both, were the most important clinical features to discriminate patients with RA with and without histologically proven RV. The presence of a high number of EAMs and a higher weighted EAM score in patients with RA suspected of vasculitis were also associated with an increased probability of histologically proven RV. After adjustment for EAMs, only the combination of an increased serum IgA RF level and a decreased serum C3 level appeared to make an additional contribution to the diagnosis histologically proven RV. Evidence of systemic vasculitis was found in a muscle biopsy of the rectus femoris in 9/14 (64%) patients with vasculitis with neuropathy and in 3/11 (27%) patients with purpura/petechiae and vasculitis of the skin.

CONCLUSIONS

In the diagnostic process of RV the presence of peripheral neuropathy and/or purpura/petechiae or a high weighted EAM score will increase the probability of histologically proven RV. Of the circulating factors previously suggested to be markers for RV only IgA RF and C3 further increase the probability of histologically proven RV and may be useful to guide diagnostic decisions.

The spectrum of cutaneous lesions in rheumatoid arthritis: a clinical and pathological study of 43 patients

INTRODUCTION

Rheumatoid arthritis (RA) is an idiopathic arthropathy syndrome that has a propensity to affect the small joints of the hands and feet with extra-articular manifestations comprising skin lesions, neuropathy, pericarditis, pleuritis, interstitial pulmonary fibrosis and a systemic polyarteritis nodosa (PAN)-like vasculitic syndrome. The most widely recognized skin lesion is the rheumatoid nodule. Other skin manifestations are poorly defined.

MATERIALS AND METHODS

Using a natural language search of the authors' outpatient dermatopathology databases, skin biopsies from 43 patients with RA were selected for retrospective analysis in an attempt to define the dermatopathological spectrum of RA and its clinical correlates.

RESULTS

The biopsies were categorized by the dominant histologic pattern, recognizing that in most cases there were additional minor reaction patterns. Palisading and/or diffuse interstitial granulomatous inflammation was the dominant pattern seen in 21 patients; the lesions included nodules, plaques and papules with a predilection to involve skin over joints. Besides interstitial histiocytic infiltrates and variable collagen necrobiosis, these cases also showed interstitial neutrophilia, vasculitis and pauci-inflammatory vascular thrombosis. The dominant morphology in 11 other patients was vasculopathic in nature: pauci-inflammatory vascular thrombosis, glomeruloid neovascularization, a neutrophilic vasculitis of pustular, folliculocentric, leukocytoclastic or benign cutaneous PAN types, granulomatous vasculitis, and lymphocytic vasculitis and finally occlusive intravascular histiocytic foci for which the designation of "RA-associated intravascular histiocytopathy" is proposed. Rheumatoid factor (RF) positivity and active arthritis were common in this group, with anti-Ro and anticardiolipin antibodies being co-factors contributing to vascular injury in some cases. Immunofluorescent testing in three patients revealed dominant vascular IgA deposition. In nine patients, the main pattern was one of neutrophilic dermal and/or subcuticular infiltrates manifested clinically as urticarial plaques, pyoderma gangrenosum and panniculitis.

CONCLUSIONS

The cutaneous manifestations of RA are varied and encompass a number of entities, some of which define the dominant clinical features, such as the rheumatoid papule or subcutaneous cords, while others allude to the histopathology, i.e. rheumatoid neutrophilic dermatosis. We propose a more simplified classification scheme using the adjectival modifiers of "rheumatoid-associated" and then further categorizing the lesion according to the dominant reaction pattern. Three principal reaction patterns are recognized, namely extravascular palisading granulomatous inflammation, interstitial and/or subcuticular neutrophilia and active vasculopathy encompassing lymphocyte-dominant, neutrophil-rich and granulomatous vasculitis. In most cases, an overlap of the three reaction patterns is seen. Co-factors for the vascular injury that we believe are integral to the skin lesions of RA include RF, anti-endothelial antibodies of IgA class, anti-Ro and anticardiolipin antibodies.

Extraosseous manifestations of rheumatoid arthritis in the foot and ankle

The immune mediated pathologic effects of rheumatoid arthritis on osteoarticular tissues are well delineated in the orthopaedic and medical literature. Less well explored are the extraosseous manifestations of rheumatoid arthritis. The rheumatoid disease process can affect virtually any organ system or tissue in the human body; from scleritis, arteritis, and splenomegaly to neuropathy, bursitis, and tendinopathy. The scope of this treatise is to define better for the clinician the extraosseous presentation of rheumatoid arthritis in the foot and ankle.

Determination of IgA- and IgM-rheumatoid factors in patients with rheumatoid arthritis with and without nephropathy

OBJECTIVE

To clarify the characteristics and pathogenesis of renal disorders in patients with rheumatoid arthritis (RA).

METHODS

In this study, 143 patients with RA were included, from whom 43 with urinary abnormalities were biopsied. Serum rheumatoid factor (RF) concentrations of IgA and IgM isotypes were also measured in these patients by enzyme linked immunosorbent assay.

RESULTS

Light microscopy of renal biopsy specimens showed minor glomerular abnormalities in six patients, mesangial proliferative glomerulonephritis (GN) in 21, membranous nephropathy in seven, renal amyloidosis in seven, and tubulointerstitial nephritis in two. Twelve patients with mesangial proliferative GN and one with minor glomerular abnormalities were found by immunofluorescence microscopy to have abnormalities consistent with IgA GN. Although the concentrations of IgA-RF in patients with IgA GN were slightly raised compared with those with glomerulopathy established by biopsy but not associated with IgA GN, the concentrations of IgA-RF were higher in patients with RA with vasculitis or interstitial pneumonia than those with RA complicated by IgA GN.

CONCLUSIONS

Mesangial proliferative GN, including IgA GN, may be a frequent renal lesion in Japanese patients with RA. IgA-RF may play little pathogenetic part in the development of IgA GN in RA.

Systemic and anti-neuronal auto-antibodies in patients with paraneoplastic neurological disease

Sera from 23 patients with paraneoplastic disease of the central nervous system (PNS) were examined for the presence of anti-neuronal (anti-Hu, anti-Yo/PCA) and anti-Ri) and systemic auto-antibodies, including antibodies against DNA, centromeres, nRNP, Sm antigen, Scl-70, Ro(SS-A), La(SS-B), mitochondria, thyroid antigens, parietal calls, brush border antigen and rheumatoid factor. As controls, sera from 33 patients with small cell lung cancer, 33 with ovarian cancer and 7 with breast cancer and from 107 aged-matched healthy persons were used. Systemic auto-antibodies were found in 52% of patients with paraneoplastic neurological syndromes compared with only 16% (P = 0.001) in the control group with cancer only and 15% in the group of healthy controls. The relatively high percentage of systemic auto-antibodies in patients with PNS indicates that there is a genetic susceptibility to the development of auto-immune phenomena. This may provide an explanation for the relatively rare occurrence of PNS in patients with cancer.

Clinical implications of IgA rheumatoid factor subclasses

OBJECTIVES

To evaluate the diagnostic and pathogenetic significance of IgA rheumatoid factor (RF) subclasses in rheumatoid arthritis (RA).

METHODS

Rheumatoid factors of the IgA class and IgA1 and IgA2 subclasses were measured by enzyme linked immunosorbent assay in 58 patients with RA, 31 patients with other rheumatic diseases, 30 non-rheumatic individuals with increased concentrations of IgA RF, and in 100 randomly selected healthy controls.

RESULTS

Using a 95% cut off for the controls, 55% of the RA patients had increased total IgA RF, 64% IgA1 RF, and 60% IgA2 RF. RA patients with extraarticular manifestations more often had increased concentrations of IgA RF and both subclasses than patients without such manifestations (p < or = 0.01). Nearly all (31/32) RA patients with increased IgA RF had increases in both IgA RF subclasses, compared with 67% (20/30 of nonrheumatic symptom free individuals with increased IgA RF (p = 0.002).

CONCLUSION

Increased concentrations of the IgA2 RF subclass appears to be more specific for RA than increased IgA1 RF. Measurement of IgA RF subclasses may be clinically useful.

Raised IgA rheumatoid factor (RF) but not IgM RF or IgG RF is associated with extra-articular manifestations in rheumatoid arthritis

In rheumatoid arthritis (RA) seropositivity has been associated with poor prognosis including bone erosions and extra-articular manifestations. However, findings have been conflicting on the association between individual rheumatoid factor (RF) isotypes and extra-articular manifestations. In this study the occurrence of extra-articular manifestations was examined in the context of the RF isotype patterns rather than individual RF isotypes. IgM, IgG and IgA RF was measured by ELISA in 74 patients with RA and the findings correlated with the presence or absence of extra-articular manifestations. Of the IgA RF positive patients 80% had one or more extra-articular manifestations. In contrast, only 21% of patients with raised IgM and/or IgG RF but normal IgA RF had some extra-articular manifestations and 27% of the seronegative patients. It is concluded that the previously reported association between raised RF and extra-articular manifestations in RA can largely be attributed to the IgA RF isotype.

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.

Disease manifestations in patients with isolated elevation of IgA rheumatoid factor

In this retrospective study a comparison was made between the disease manifestations in patients with isolated elevation of IgA rheumatoid factor (RF) and patients with elevation of IgM RF. Of the 28 patients with isolated elevation of IgA RF, 14 (50%) had rheumatoid arthritis (RA) and 9 (32%) miscellaneous other inflammatory rheumatic disorders. It was found that 61% of these 23 rheumatic patients had disease manifestations from mucous membranes or secretory organs compared to 18% in the IgM RF positive group (p = 0.020). Patients with RA and an isolated elevation of IgA RF had more often mucosal or secretory symptoms than RA patients with elevation of IgM RF. We suggest that IgA RF may be a marker for activation of the mucosal or secretory immune system. The relationship between IgA RF and non-articular symptoms is discussed.

No interference of rheumatoid factor(s) with toxoplasmosis IgM determination in infancy

Sera from 263 newborns and infants suspected of congenital toxoplasmosis were tested for the presence of rheumatoid factor (RF) by the latex agglutination test, of which 40 were also tested by the enzyme-linked immunosorbent assay (ELISA). RF was detected in only one serum sample (0.38%), suggesting that false-positive results of the IgM-indirect fluorescent antibody test and the IgM-ELISA due to RF is most unusual in infancy.

IgG and IgA antibodies to the collagen-like region of C1q in rheumatoid vasculitis

We investigated the presence of IgG and IgA antibodies to C1q in serum samples from 80 patients with rheumatoid arthritis (RA), 31 patients with rheumatoid vasculitis, and 80 healthy controls. IgG and IgA antibodies to C1q, as measured by enzyme-linked immunosorbent assay, were found in less than 5% of the sera from RA patients and from healthy controls. In contrast, IgG and IgA antibodies to C1q were found in 29% and 61%, respectively, of the sera from patients with rheumatoid vasculitis. The occurrence of IgA antibodies to C1q has not been previously demonstrated. These results also demonstrate that IgG antibodies to C1q do not occur exclusively in systemic lupus erythematosus patients: Sera of patients with rheumatoid vasculitis frequently contain IgG or IgA antibodies to C1q, which contribute to immune complex formation.

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)

Serodiagnosis of respiratory syncytial virus (RSV) infection in children as measured by detection of RSV-specific immunoglobulins G, M, and A with enzyme-linked immunosorbent assay

The diagnostic value of an enzyme-linked immunosorbent assay for detection of respiratory syncytial virus (RSV)-specific immunoglobulin G (IgG), IgM, and IgA in sera from infants and children with proven RSV infection, from a control group, and from patients with symptoms of viral respiratory disease was analyzed. Compared to virus isolation and RSV antigen detection methods, the sensitivity of this assay was 87% and the specificity was 79%. For IgG alone, these were 45 and 92%, for IgM alone they were 48 and 92%, and for IgA alone they were 74 and 95%, respectively.

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

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.

A useful method for determining class-specific rheumatoid factors with computerized analyses of data

A simple and sensitive enzyme-linked immunosorbent assay (ELISA) was developed to determine rheumatoid factors (RFs) of IgG, IgA and IgM class. Standardisation was performed with a standard reference serum for IgM-RF, calibrated according to the WHO preparation, and with the serum of a patient containing high levels of IgA- and IgG-RF. The sigmoidal shaped calibration curve was fitted with a computerized four parameter logistic model with simplified mathematical computations. This method provided to be more accurate for measuring RF levels, as judged by the smaller residuals, than logit or log-linear transformations. The considerable reduction in processing time, which is obtained by the computerized analysis of data, makes this method of class-specific RF determination suitable for routine analysis.

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

Stored samples from within the first year of disease of 119 patients with rheumatoid arthritis (RA) enrolled in a long-running prospective study have been studied for the presence of IgM and IgA rheumatoid factors (RF), using agglutination of rabbit IgG-coated red blood cells to detect IgMRF and an ELISA technique using rabbit IgG coated on the microtitre plates and labelled F(aB)2 fragment of goat anti-IgA. Outcome measures at a mean follow-up of 10.1 years (range 3-20) included the Steinbrocker functional grade and grading of erosive changes on hand and feet Xrays using a modification of Lawrence's method. Both IgA and IgG levels at presentation correlated significantly with outcome measured by erosive changes and functional grade at a mean of 10 years and with the time of first appearance of erosions. In patients who are IgMRF negative early in the disease, IgARF positivity indicates a greater chance of developing both erosions and impaired function than when both tests are negative. IgARF positivity seems to precede IgMRF.

Significance of rheumatoid factors in an eight-year longitudinal study on arthritis

A community-based cohort comprising 150 patients with recent-onset seropositive arthritis or seronegative oligoarthritis or polyarthritis was monitored for 8 years. Of the different rheumatoid factor (RF) tests, the initial positivity in the most sensitive assays (latex slide test and IgM-RF by enzyme immunoassay) was the most reliable factor when distinguishing between the erosive and nonerosive cases. The individual RF isotypes fluctuated in four serial specimens, but each patient tended to preserve his or her reactivity pattern. Seroconversion from positive to negative within the 1st year of follow-up did not indicate a particularly good long-term prognosis.

Quantitation of rheumatoid factors (RF) of IgM, IgA and IgG isotypes by a simple and sensitive ELISA. Discrimination between false and true IgG-RF

An enzyme-linked immuno-sorbent assay (ELISA) for quantitation of rheumatoid factors (RF) of IgM, IgA and IgG isotypes has been established. A complex of human serum albumin (HSA) and rabbit IgG anti-HSA antibodies is used as antigen for RF. The binding of RF is detected by stepwise additions of biotinylated monoclonal antibodies specific for human IgM, IgG or IgA, alkaline phosphatase-conjugated streptavidin, and substrate. The assay is simple and applicable to routine testing of large numbers of sera. It discriminates between false and true IgG-RF by papain digestion of sera that turn out positive by the screening for IgG-RF. Of 241 randomly selected patients with rheumatoid arthritis (RA) as well as other rheumatoid and infectious diseases, 110 were Waaler-Rose-positive while 127 were IgM-RF-positive in ELISA. The correlation between the Waaler-Rose test and IgM-RF ELISA was highly significant (r = 0.82). By testing 65 of these sera (all IgM-RF positive), 25 (39%) were also true IgG-RF positive (42 (64%) in the screening). When 40 Waaler-Rose-positive RA patients were tested, 20 and 21 were also positive for IgG- and IgA-RF, respectively. Eight IgM-, one IgA- and no IgG-RF positive tests were recovered when 48 Waaler-Rose negative RA patients were studied.

Standardisation of serological tests for rheumatoid factor measurement

Standardisation of quantitative data obtained by several types of rheumatoid factor test was achieved by the use of a reference serum preparation. Interlaboratory comparability improved for the latex fixation test, the Waaler-Rose test, the IgM RF test by an enzyme linked immunosorbent assay (ELISA), and for the antiperinuclear factor test. Use of a common method and latex preparation was not sufficient to improve comparability for the latex test. The comparability of IgM RF tests by immunofluorescence (IF) was not changed by reading against a common reference. It is concluded that expression in international units, as defined by the World Health Organisation (WHO), improves interlaboratory comparison of quantitative data in rheumatoid serology.

Immunogenetic heterogeneity of rheumatoid arthritis

Association of HLA-DR4/Dw4 with rheumatoid arthritis (RA) is well established, but conflicting data exist on a possible association with the severity of the disease, including its extra-articular manifestations. In order to investigate whether a subgroup of RA is preferentially associated with DR4, HLA typing was performed in two groups of patients with severe extra-articular manifestations (Felty's syndrome and histologically proved leucocytoclastic vasculitis), patients with severe joint destruction (seropositive and seronegative), a group with only mild joint destruction, and in healthy controls. The frequency of HLA-DR4 was significantly raised in all patient groups compared with that in healthy controls. The two groups with severe extra-articular manifestations, however, both had a DR4 frequency of 92%, which was significantly (p = 0.002) higher than the 62.7% found in the remaining patients. No significant differences were observed between severe or mild joint destruction and seropositivity or seronegativity in the groups without the above-mentioned extra-articular manifestations. From these data we concluded that DR4 is preferentially associated with severe extra-articular disease manifestations of RA. This observation provides an immunogenetic basis for the disease heterogeneity and for the immunological analogy between RA and leprosy.