Impact of anti-human IgG hinge peptide antibodies on identification of patients with early seronegative rheumatoid arthritis.

OBJECTIVES: The early diagnosis of seronegative rheumatoid arthritis (SNRA), characterised by the absence of rheumatoid factor and anti-citrullinated antibody, involves a greater challenge compared to seropositive RA (SPRA). This study aimed to assess the discriminatory potential of anti-human IgG hinge antibodies (AHAs) for patients with early SNRA. METHODS: DMARDs-naive patients with SPRA (n=43), SNRA (n=21), and non-RA (n=49), with disease duration < 2 years, were included. Antigens comprised IgG1 or IgG4 F(ab')2 cleaved by pepsin or MMP-3 and their hinge peptide analogues. Eight IgG anti-hinge antibodies (AHAs) against these antigens were measured in sera from the patients and 58 healthy controls (HCs) using ELISA. Serum CRP and MMP-3 levels, and clinical disease activity index (CDAI), were obtained from medical records. The area under the curve (AUC) obtained from logistic regression and receiver operating characteristic curve analyses were used as a discriminant indicator. RESULTS: The levels of the IgG AHAs were as follows: SPRA≥SNRA≈non-RA>HC. None of the AHAs were effective in discriminating SNRA from non-RA. However, the combination of MMP-3 and AHAs against IgG4 hinge peptide analogues demonstrated the utility (AUC=0.94). Furthermore, combination of MMP-3, AHAs against IgG1 hinge peptide analogues and CDAI maximally exerted discriminatory power (AUC=0.997). CONCLUSIONS: Specific AHAs in combination with MMP-3 and CDAI are potentially useful to discriminate SNRA from non-RA.

Cluster analysis defines four groups of Japanese patients with adult-onset Still's disease.

OBJECTIVES: To define groups and characterize differences in the prognosis of patients with adult-onset Still's disease (AOSD). METHODS: We performed a retrospective cohort study. Patients with AOSD were grouped using hierarchical unsupervised cluster analysis according to age, sex, clinical features, and laboratory data. The primary endpoints were overall survival and drug-free remission rate. RESULTS: A total of 153 patients with AOSD were placed into four clusters. Those in Cluster 1 had a young onset, tended to be female, and had fewer complications and moderate ferritin concentrations. Those in Cluster 2 had a young onset and had more complications and higher ferritin concentrations. Those in Cluster 3 had a young onset, tended to be male, and had no lymphadenopathy and fewer complications. Those in Cluster 4 had an older onset, tended to be female, and had more complications and higher ferritin concentrations. Overall survival tended to be lower (P = .0539) in Cluster 4, and drug-free remission was higher in Clusters 1, 2, and 3 [hazard ratios (HRs) 2.19, 3.37, and 3.62 vs. Cluster 4, respectively]. CONCLUSIONS: Four groups of AOSD that have distinct clinical manifestations, ferritin concentrations, severity, and drug-free remission rate were identified, which were lowest in Cluster 4. Graphical Abstract.

Usefulness of the severity classification for predicting drug-free remission in Japanese patients with adult-onset Still's disease.

OBJECTIVES: To investigate the usefulness of severity classification for predicting outcomes in patients with adult-onset Still's disease (AOSD). METHODS: This was a multi-centre retrospective cohort study. AOSD patients were classified into mild, moderate, and severe groups based on severity classification (Japanese Ministry of Health, Labour and Welfare) during the initial treatment, and clinical features were compared among these groups. The primary endpoints were the AOSD-related mortality and drug-free remission rate. For comparison, the same analysis was performed in parallel for patient groups stratified by the modified Pouchot systemic score. RESULTS: According to severity classification, 49 (35%), 37 (26%), and 56 patients (39%) were classified into mild, moderate, and severe groups, respectively. Patients in the severe group showed higher frequency of severe complications and the use of biological agents. Although AOSD-related survival was not significantly different (p = .0776), four of the five fatal cases were classified into the severe group. The severe group showed a reduced rate of drug-free remission (p = .0125). Patient groups classified by systemic score did not correlate with survival or drug-free remission. CONCLUSIONS: Severity classification is useful for predicting outcomes in patients with AOSD.

Clinical features of elderly-onset Adult-onset Still's disease.

OBJECTIVES: To clarify the characteristics of patients with elderly-onset Adult-onset Still's disease (AOSD). METHODS: Patients were classified into elderly-onset (>60 years: 47 patients) and younger-onset (≤60 years: 95 patients) groups according to their age at diagnosis of AOSD. Clinical features, treatments, and prognosis were compared between the elderly-onset and younger-onset groups. RESULTS: In the elderly-onset group, compared with the younger-onset group, typical skin rashes were less frequent (21.3% vs 58.9%, respectively; p < .0001), whereas pleuritis (27.7% vs 7.4%, respectively; p = .0011) and disseminated intravascular coagulation (19.1% vs 2.1%, respectively; p = .0004) were more frequent, and serum ferritin levels were higher (median 12,700 ng/ml vs 2526 ng/ml, respectively; p < .0001). Overall survival and AOSD-related survival were reduced (p = .0006 and p = .0023, respectively) and drug-free remission was less frequent (p = .0035) in the elderly-onset group compared with the younger-onset group. CONCLUSIONS: Our results demonstrated that elderly-onset AOSD patients had several characteristics that differed from younger-onset AOSD patients, including less typical skin lesions, more AOSD-related complications, higher ferritin levels, and poorer prognoses.

Intestinal Behçet's disease with pyoderma gangrenosum successfully treated with the combination therapy of adalimumab and glucocorticoids.

A 24-year-old male presented with orogenital ulcers, folliculitis, and progressive painful skin ulcers with a raised inflammatory border. Colonoscopy revealed volcano-shaped intestinal ulcers in the ascending colon, and hence, he was diagnosed as intestinal Behçets disease (BD) with pyoderma gangrenosum (PG). Treatment with systemic glucocorticoids and adalimumab dramatically improved the patient's symptoms. Our case demonstrates that early induction of adalimumab may contribute to the successful treatment of such difficult-to-treat conditions as intestinal BD with PG.

Beneficial use of serum ferritin and heme oxygenase-1 as biomarkers in adult-onset Still's disease: A multicenter retrospective study.

BACKGROUND: Heme oxygenase (HO)-1 is a heme-degrading enzyme highly expressed in monocyte/macrophage, serum levels of which may be promising biomarker for adult-onset Still's disease (AOSD). We here report data on the use of serum ferritin and HO-1 levels in AOSD. METHODS: Under the Hypercytokinemia Study Group collaboration, we collected sera from a total of 145 AOSD patients. Three independent experts judged whether the patients were definite AOSD depending on the clinical information. These 91 'definite AOSD' patients were further divided into active, remission, and relapse groups. Forty-six cases of systemic vasculitis, sepsis, etc. were included as disease controls. Serum ferritin and HO-1 levels were measured using ELISA. Associations between clinical symptoms, serum ferritin, and HO-1 were explored. Multivariate regression analysis was performed to identify independent variables associated with definite AOSD diagnosis. RESULTS: Serum ferritin and HO-1 levels were significantly higher in active and relapsed AOSD cases compared to disease controls, and were reduced by the treatment. Although a significant correlation was found between serum ferritin and HO-1 levels, a discrepancy was found in some cases such as iron-deficiency anemia. Receiver operating characteristic analysis identified optimal levels of serum ferritin (>819 ng/ml; sensitivity 76.1% and specificity 73.8%), and serum HO-1 (>30.2 ng/ml; sensitivity 84.8% and specificity 83.3%) that differentiated AOSD from controls. Interestingly, 88.9% of patients with AOSD who relapsed exceeded the cut-off value of serum HO-1 > 30.2 ng/ml, but only 50.0% exceeded serum ferritin >819 ng/ml (p = .013), suggesting that serum HO-1 levels may be a convenient indicator of AOSD disease status. Multivariate analysis identified neutrophilia, RF/ANA negativity, sore throat, and elevated serum HO-1 as independent variables associated with AOSD diagnosis. CONCLUSION: We confirmed that serum ferritin and HO-1 serve as highly specific and sensitive biomarkers for AOSD. A future prospective study with large sample size is necessary to determine whether these biomarkers could be included in Yamaguchi's Criteria.

[IgM Antibody against IgG Antibody Binding to Antigen, So-Called Anti-Antibody, Reacts Mainly with F (ab')2 Fragment Possessing Antibody Activity].

OBJECTIVE: To develop enzyme-linked immunosorbent assay (ELISA) for measurement of IgM antibody (anti-antibody) against human IgG antibody that is binding to antigen, to distinguish anti-antibody from other antiglobulins, e.g. rheumatoid factor (RF), and to search their localization of epitope on IgG molecule. METHODS: We chose purified human IgG anti-dsDNA antibody from a patient with systemic lupus erythematosus as IgG antibody and calf thymus dsDNA as antigen. IgG F (ab')2 fragment was obtained by digestion of the IgG with pepsin. Those IgG and IgG F (ab') 2 with anti-dsDNA antibody were reacted with pre-coated dsDNA and formed immune complex on ELISA plate. On the other hand we prepared ELISA plate on which those IgG and IgG F (ab') 2 were coated directly for measurement of IgM RF and IgM antihinge antibody. Twenty-three sera from patients with rheumatoid arthritis were tested. RESULTS: Correct IgM anti-antibodies were obtained after subtraction of absorbance of IgM anti-dsDNA anti- bodies. Remarkable correlation between IgM anti-antibodies obtained by using whole IgG and those by using IgG F(ab')2(n=23, r²=0.914, p=1.11X10-12). There were correlations neither between IgM antiantibodies and IgM RF(n=23, r²=0.001, p=0.889) nor between IgM antiantibodies and IgM antihinge antibodies (n=23, r²=0.063, p=0.249). CONCLUSIONS: IgM molecule with anti-antibody specificity seems to be different from IgM RF and IgM antihinge antibody. Moreover, epitope recognized by IgM anti-antibody seems to localize on IgG F (ab') 2 but not on hinge region. [Original].

Therapeutic response of patients with adult Still's disease to biologic agents: multicenter results in Japan.

OBJECTIVE: The efficacy of biologics in treating adult Still's disease (ASD) is suggested, but the information is still lacking and the validation is insufficient. To determine the efficacy of several biologic agents in refractory ASD in Japan, a multicenter survey was performed. METHOD: Clinical data on 16 ASD patients who had been treated with at least 1 of the biological agents (total 24 occasions) were collected retrospectively. RESULTS: Infliximab was used in 9 cases, etanercept in 4, and tocilizumab in 11. Half of the patients that had been treated initially with infliximab or etanercept were changed to another biologics. Tocilizumab was effective in cases switched from another 2 drugs. Tocilizumab showed efficacy in treating both systemic and arthritic symptoms and showed apparent steroid-sparing effect and the highest continuation rate. CONCLUSION: Tocilizumab may be a promising biologic agent in refractory ASD.

[Rheumatic diseases and research on laboratory medicine: new applications of old knowledge].

Although the etiology of rheumatic diseases has not been elucidated, it seems to be involved in excessive autoimmune responses. In 1976, we began to research rheumatic diseases, especially rheumatoid arthritis. Anti-human immunoglobulin allotype antibodies in Japanese sera were collected from blood donors or patients by hemagglutination and the hemagglutination inhibition method using anti-D sensitized erythrocytes. Many rheumatoid factors without any specificity to IgG allotypes (Gm allotypes) were detected in patient sera. On the other hand, so-called anti-antibodies, Andresen type but not Milgrom type, were mainly detected in blood donors. Thirty-nine sera possessing anti-Gm and anti-Km antibody specificities were finally obtained by screening about 80,000 Japanese. The antibody to G1m (f) was most frequently detected, but the antibody to G1m (z), which is an allele of G1m (f), was not obtained. Quantitative evaluation of rheumatoid factors (RF) and anti-citrullinated protein antibodies (ACPA) was adopted in the 2010 ACR/EULAR classification criteria for rheumatoid arthritis; however, quality management of RF has been incompletely implemented in Japan. We therefore mounted an effort to standardize the cutoff value. We found marked hyperferritinemia in patients with active adult Still's disease in 1987. Additionally, ratios of glycosylated ferritin in the patients were extremely reduced, even if they came into the inactive phase. This depressive production of glycosylated ferritin might be a marked characteristic of this disease. Finally, the development of musculoskeletal ultrasonography in rheumatic diseases is introduced.

Successful Treatment of Systemic Sclerosis-related Pericarditis with Mycophenolate Mofetil and Low-dose Prednisolone.

We herein report a case of systemic sclerosis (SSc)-related pericarditis successfully treated with mycophenolate mofetil (MMF) and low-dose prednisolone (PSL). The patient was a 72-year-old woman with anti-centromere antibody. Her clinical manifestations were Raynaud phenomenon, bilateral pleural effusion, pericardial effusion and skin tightness. Based on the findings of exudative pericardial effusion with the absence of pulmonary arterial hypertension from the results of the cardiac catheter and pericardiocentesis, she was diagnosed with SSc-related pericarditis and treated with PSL10 mg and MMF 1 g per day, leading to the complete resolution of pericarditis. These findings suggested that MMF and low-dose PSL were effective for SSc-related pericarditis.

[How to reduce unnecessary orders of laboratory tests].

The medical insurance system in Japan has been focusing on how to reduce the annual increases in medical expenses. In this context, the circumstances in the laboratory department in large hospitals have been growing more strict. Therefore, medical staff working in large hospitals need to know how to reduce the expenditure consumed in laboratory tests. In this paper we report economical loss resulted from physicians' excessive test-orders and suggest how to manage the problem.

[Utility of musculoskeletal ultrasonography in rheumatic diseases].

Musculoskeletal ultrasonography (MSUS) possessing grey-scale and Doppler mode has become an established imaging modality for the diagnosis and follow up of patients with rheumatic diseases. Among rheumatic diseases, rheumatoid arthritis (RA) has been recognized as a good disorder to examine the joint inflammation as known synovitis. Early diagnosis and therapeutic intervention have given good outcomes to patients with RA. The 2010 RA classification criteria was reported and early arthritis patients has been diagnosed as RA, although the diagnostic and discriminative abilities of the 2010 criteria are not well known in Japanese. In the new criteria, synovitis is detected as joint swelling or tenderness on physical examination. Now we have expected if MSUS were used for detection of true synovitis, because we have confirmed that sensitivity of synovitis detection by MSUS was superior to that by physical examination.

Prevalence and clinical implication of complex atherosclerotic plaque in the descending thoracic aorta of Japanese patients assessed by transesophageal echocardiography.

BACKGROUND: Aging and westernization of lifestyle has accelerated the prevalence and severity of atherosclerotic cardiovascular diseases in the Japanese population. The aim of this study was to examine the prevalence of complex plaque formation in the descending thoracic aorta (DTA) as assessed by real-time 3-dimensional transesophageal echocardiography (3DTEE) and its relation to clinical factors. METHODS AND RESULTS: A prospective analysis of atherosclerotic plaque in the DTA of 350 consecutive patients who were clinically indicated for real-time 3DTEE was performed. Systematic assessment of the DTA plaques was performed using a biplane mode from the aorta at the level of the stomach to the aortic arch. When a large plaque (>4mm) was identified, detailed 3-dimensional (D) observations were performed using a 3D zoom mode. Complex plaque was defined as either mobile or an ulcer-like pouch in the DTA. Complex plaques were detected in 51 patients (15%), who were more advanced in age and had a higher prevalence of chronic kidney disease. A multivariate analysis revealed that the presence of complex plaque was an independent predictor of renal impairment. CONCLUSIONS: The prevalence of complex plaque was not low in the this Japanese study population. A close association between complex plaque and renal dysfunction raises the possibility that complex plaque in the DTA is a potential cause of renal dysfunction.

Assessment of the aortic root using real-time 3D transesophageal echocardiography.

BACKGROUND: Precise evaluation of the aortic root geometry prior to transcatheter aortic valve implantation is important for procedural success in patients with aortic stenosis (AS). To determine the potential for 3-dimensional transesophageal echocardiography (3DTEE), the aims of the present study were: (1) to assess the accuracy of 3DTEE measurements of the aortic root using multidetector computed tomography (MDCT) as a reference, and (2) to examine whether aortic root geometry differs between patients with and without AS. METHODS AND RESULTS: 3DTEE and contrast-enhanced MDCT were performed in 35 patients. Multiplanar reconstruction was used to measure the left ventricular outflow tract (LVOT) and aortic annulus diameter/area, aortic valve area (AVA), and distances between the annulus and coronary artery ostium. The same 3DTEE measurements were performed in patients with (n=71) and without AS (n=80). Aortic annular and LVOT areas measured by 3DTEE were slightly but significantly smaller compared with values obtained with MDCT. Both methods revealed that the aortic annulus and LVOT have an oval shape. Aortic annular and LVOT area, AVA and the distances between the aortic annulus and the coronary ostia correlated well between the 2 modalities. Only minor differences in aortic root geometry were observed between patients with AS and those without. CONCLUSIONS: The geometry of the aortic annulus can be reliably evaluated using 3DTEE as an alternative to MDCT for the assessment of aortic root.

Comparison of low-field dedicated extremity magnetic resonance imaging with articular ultrasonography in patients with rheumatoid arthritis.

To compare magnetic resonance imaging (MRI) and ultrasonography (US) in the detection of joint inflammation of rheumatoid arthritis (RA), 6 patients with RA were examined by US and low-field 0.3-T nonenhanced dedicated extremity MRI (compacTscan). All patients were females, with mean age of 50.2 years, mean disease duration of 13.5 years, and mean disease activity score (DAS)28-CRP of 1.78. Each patient was treated with either infliximab, etanercept, adalimumab, or tocilizumab. Intercarpal joints, radioulnar joints, second through fifth proximal interphalangeal (PIP) joints, and first through fifth metacarpophalangeal (MCP) joints (a total of 132 joints, 22 joints in each patient) were assessed by MRI for presence of joint inflammation. A total of 156 joints (24 first interphalangeal and radiocarpal joints plus the above 132 joints), were assessed by grayscale US (GS-US) and power Doppler US (PD-US) for presence of joint inflammation by two trained ultrasonographers. We assessed correlations between joint inflammations on MRI and GS-US/PD-US, and also interobserver correlation between the two ultrasonographers by calculating intraclass correlation coefficients (ICC). Synovial hypertrophy and/or synovial fluid was detected in 74/156 joints on GS-US, and synovitis was detected in 10/156 joints on PD-US and in 38/132 joints on MRI. Using PD-US as a reference, sensitivity of MRI in detection of synovitis was 80%. Using MRI as a reference, sensitivity of PD-US was 21%. Specificity of PD-US was higher than that of MRI. Overall agreement between GS-US and MRI and between PD-US and MRI was 0.56 and 0.76, respectively, suggesting that results of PD-US are close to those of MRI. ICC was 0.545 for GS-US and 0.807 for PD-US, suggesting specificity of PD-US in detecting joint inflammation. Our results show that findings of PD-US correlated with those of MRI. Low-field MRI and PD-US are useful tools for assessment of patients with RA.

[Incidence of serum rheumatoid factors in elder non-rheumatic individuals].

With the aging of the Japanese population, an increase in the number of elderly patients with rheumatoid arthritis (RA) has been noted in recent years. Although rheumatoid factor (RF) is found in a high proportion of RA patients, it is also known to be present in non-rheumatoid patients. However, no studies have investigated the rate of RF positivity in elderly non-rheumatoid individuals. In this study, we examined the rate of RF positivity in such individuals and the association between smoking and RF production. The subjects were 25 men (aged 67 to 87 years, with a mean of 74.0) and 24 women (aged 60 to 86 years, with a mean of 70.7). Of these subjects, nine (18.4%), including seven men, were RF-positive. A significant positive correlation was observed between age and RF values (n=49, p<0.05). Of 23 subjects with a smoking habit, eight (34.8%) were RF-positive. In contrast, only one (3.8%) of 26 nonsmokers was RF-positive. This difference in the rate of RF positivity was significant (p<0.01). In addition, a significant positive correlation was noted between the duration of smoking and rate of RF positivity (p<0.05), particularly in men (p<0.01). These results suggest that smoking is closely involved in RF production in the elderly.

IgG anti-hinge antibodies against IgG4 F(ab')2 fragments generated using pepsin are useful diagnostic markers for rheumatoid arthritis: implications of the possible roles of metalloproteinases and IgG subclasses in generating immunogenic hinge epitopes.

BACKGROUND: Pepsin agglutinators, discovered over 50 years ago, have been recently referred to as anti-hinge antibodies (AHAs) because of their reaction with the IgG hinge epitope. AHAs have different reactivity for each hinge epitope generated by each protease that cleaves the hinge region at different sites. Moreover, AHAs have different reactivity against different hinge epitopes derived from each IgG subclass even when the same protease is used. Since the expression of matrix metalloproteinase-3 (MMP-3) is enhanced in rheumatoid arthritis (RA), AHA production could also be increased. The purpose of this study was to determine whether the levels of AHAs against IgG hinge epitopes produced by MMP-3 are elevated in RA. METHODS: The serum levels of IgG or IgA AHAs against the IgG1/IgG4 F(ab')2 fragments, generated by either MMP-3 or pepsin, were measured using ELISA in 111 patients with RA and 81 healthy controls (HC). Receiver operating characteristic (ROC) analysis was used for obtaining optimal cutoff values and cutoff values indicating high specificity (> 95%) of the AHA. The targeted epitope of a specific AHA was investigated through inhibition ELISA. RESULTS: Seven AHAs were statistically higher in RA patients than in HC, except IgG AHA against IgG1 F(ab')2, which was generated by MMP-3 proteolytic cleavage. The areas under the ROC curve were 0.66-0.80, although the sensitivities at high specificity were low (5.4-24.3%). The cumulative number of positive AHAs in each individual was statistically higher in RA patients than in HC, suggesting the extreme extent of AHA repertoires in RA. Inhibition studies revealed that IgG AHAs against IgG4 F(ab')2 fragments generated by pepsin cross-reacted with IgG1 F(ab')2 fragments generated by pepsin. Multivariate logistic regression analysis identified the IgG AHA against IgG4 F(ab')2 fragments generated by pepsin as an independent variable for RA diagnosis, even in RA patients who were negative for both RF and ACPA (odds ratio 1.18, 95% CI 1.06-1.32; P = 0.003). Additional experiments using non-RA patients finally strengthened the diagnostic utility. CONCLUSION: In RA patients, we observed diversification and amplification of AHA repertoires and diagnostic utility of the specific AHA against IgG4 F(ab')2 fragments generated by pepsin but not MMP-3.

A novel scoring system based on common laboratory tests predicts the efficacy of TNF-inhibitor and IL-6 targeted therapy in patients with rheumatoid arthritis: a retrospective, multicenter observational study.

BACKGROUND: Currently, although several categories of biological disease-modifying antirheumatic drugs (bDMARDs) are available, there are few data informing selection of initial treatment for individual patients with rheumatoid arthritis (RA). Therefore, tumor necrosis factor inhibitor (TNF-i) and tocilizumab (TCZ) are treated as equivalent treatments in the recent disease management recommendations. We focused on two anticytokine therapies, TCZ and TNF-i, and aimed to develop a scoring system that predicts a better treatment for each RA patient before starting an IL-6 or a TNF-i. METHODS: The expression of IL-6 and TNF-α mRNA in peripheral blood from 45 newly diagnosed RA patients was measured by DNA microarrays to evaluate cytokine activation. Next, laboratory indices immediately before commencing treatment and disease activity score improvement ratio after 6 months in 98 patients treated with TCZ or TNF-i were retrospectively analyzed. Some indices correlated with TCZ efficacy were selected and their cutoff values were defined by receiver operating characteristic (ROC) analysis to develop a scoring system to discriminate between individuals more likely to respond to TCZ or TNF-i. The validity of the scoring system was verified in these 98 patients and an additional 228 patients. RESULTS: There was significant inverse correlation between the expression of IL-6 and TNF-α mRNA in newly diagnosed RA patients. The analysis of 98 patients revealed significant correlation between TCZ efficacy and platelet counts, hemoglobin, aspartate aminotransferase, and alanine aminotransferase; in contrast, there was no similar correlation in the TNF-i group. The cutoff values were defined by ROC analysis to develop a scoring system (1 point/item, maximum of 4 points). A good TCZ response was predicted if the score was ≥2; in contrast, TNF-i seemed to be preferable if the score was ≤1. Similar results were obtained in a validation study of an additional 228 patients. If the case scored ≥3, the good responder rates of TCZ/TNF-i were 75.0%/37.9% (p < 0.01) and the non-responder rates were 3.1%/27.6% (p < 0.01), respectively. CONCLUSIONS: The score is easily calculated from common laboratory results. It appears useful for identifying a better treatment at the time of selecting either an IL-6 or a TNF inhibitor.

[Immunologic laboratory testing in clinical practice for rheumatoid arthritis].

The recent clinical practices for rheumatoid arthritis have changed greatly. First, biologic agents such as tumor necrosis factor blocker have been developed as well as disease-modifying antirheumatic drugs, with great efficacy in intractable RA. On the other hand, the importance of early effective therapeutic intervention has been recognized since early treatment prevents the progression of joint damage. However, early diagnosis of RA is not so easy because of the lack of appropriate diagnostic criteria. New laboratory tests have appeared for the diagnosis and prognostic prediction of RA. Among them, anticyclic citrullinated peptide antibodies (anti-CCP), which bind epitopes containing citrulline, seem to be attracting the most attention. Although rheumatoid factor (RF) is the only serologic marker among the seven classification criteria of the American College of Rheumatology (ACR) for RA, variability of the RF assay within laboratories and/or between laboratories, and quality assurance has not been established. We must address the standardization of RF assay as soon as possible.