Autoantibodies in Patients with Rheumatoid Arthritis

Aim:  The aim of this study is to examine the diagnostic value of autoanitbodies in patients suffering from rheumatoid arthritis. We evaluated the presence of the following autoantibodies: rheumatoid factor (RF), antinuclear antibodies (ANAs), antibodies against cadiolipin (a-CL) and antibodies against cyclic citrullinated peptide (anti-CCP).
Methods:  We studied the presence of RF, ANA, a-CL and anti-CCP in 40 patients with rheumatoid arthritis. Rheumatoid factor was measured using nephelometric method, while ANAs were examined by indirect immunofluorescence technique using Hep-2 cells as substrate. Sera that reacted at 1/80 dilution were classified as ANA positive. Positive sera were studied up to 1/1280 dilution. A-CL and anti-CCP were measured by enzyme-linked immunosorbent assay.
Results:  RF was positive in 30 patients (75%), ANA in 15 (37%), a-CL in 10 (25%) and anti-CCP in 36 (90%). Predominant pattern of nuclear staining of ANA-positive sera was homogenous and speckled type. ANA titres were particularly low; most patients (6) had ANA titre equal to 1/80, and five patients had a titre of 1/160, while only four out of 40 had an ANA titre of 1/320.
Conclusions:  Autoimmune disorders such as RA are characterized by various autoantibodies that usually are not specific, as they are present in many other diseases. However, RF and especially anti-CCP are very often and show higher specificity for RA, being useful diagnostic serological markers. On the other hand, ANA and a-CL are less common in RA paitents; they may be useful in terms of prognosis and treatment, but they always should be evaluated in correlation with the clinical features and the rest of the laboratory findings of each patient.     

Anti-keratin antibodies in rheumatoid arthritis: frequency and correlation with other features of the disease

Anti-keratin antibodies (AKA) were detected in 68 out of 98 patients (69%) with classical or definite rheumatoid arthritis (RA). The intensity of the AKA reaction correlated significantly with articular index (AI), grip strength (GS), erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP) concentration, serum amyloid A (SAA) protein concentration, the level of antibodies against single stranded DNA (ssDNA) and the IgM rheumatoid factor (RF) titre. A significantly higher number of patients with nodules and Sj?gren's syndrome were AKA positive compared with patients without extra-articular features (EAFs) and the AKA titre was significantly greater in the former group. The mechanisms underlying appearance of AKA are not known but may relate to an as yet unidentified structural alteration of keratin in this disease or may just reflect the rheumatoid autoimmune diathesis.     

Anti-neutrophil cytoplasm antibodies in rheumatoid arthritis.

Anti-neutrophil cytoplasm antibodies (ANCA) occur occasionally in rheumatoid arthritis (RA), but their incidence and clinical significance have been unclear. In this study we have investigated 58 patients with RA. In 22 patients the disease was inactive and the remaining 36 with active disease were further subdivided into those without clinical evidence of vasculitis (26), those with cutaneous vasculitis (8) and those with systemic vasculitis (2). ANCA were demonstrated by indirect immunofluorescence in 10 of the 58 patients (17%). While both perinuclear (pANCA) and cytoplasmic (cANCA) staining were detected, pANCA were more common (70%). Neutrophil-specific anti-nuclear antibodies (ANNA) were demonstrated in a further eight sera (14%) and ANA were detected on Hep-2 cells in 30 of the 58 sera (52%). ELISAs for the detection of anti-myeloperoxidase and anti-elastase antibodies were then established. Five sera with pANCA and five that contained ANNA were negative for both anti-myeloperoxidase and anti-elastase antibodies, suggesting other as yet unidentified cytoplasmic antigens as the target molecules. However, anti-myeloperoxidase or anti-elastase antibodies were found in four sera that had homogeneous or speckled ANA on both Hep-2 cells and neutrophils. One serum contained both antibodies. The presence of ANCA detected by indirect immunofluorescence or of anti-myeloperoxidase or anti-elastase antibodies in these patients with RA was not associated with disease activity nor with the demonstration of cutaneous vasculitis or renal disease (P NS). A possible association with systemic vasculitis remains to be confirmed. There is an incomplete correlation between indirect immunofluorescence patterns and antibody specificity in ELISA systems.     

Association of rheumatoid factor with complement activation in rheumatoid arthritis and other diseases.

Rheumatoid factor (RF) is a complement activating autoantibody. In rheumatoid arthritis (RA) the rate of catabolism of complement is closely related to the titre of RF. Therefore, we have examined whether these relationships are unique to RA or will be found in non-RA disorders in which RF may be found in the circulation. We studied patients with subacute bacterial endocarditis, leprosy, tuberculosis, and a variety of other rheumatic and vasculitic disorders. We found that in all the disorders examined the RF had a complement activating potential which was equivalent to that of the RF of RA patients. Furthermore in vivo activation of complement, as exhibited by the appearance of C3 degradation products, was significantly related to higher titres of haemolytically active RF in non-RA as well as the RA group. In these respects, therefore, the RF in RA and non-RA patients is indistinguishable. A possible survival value for RF is discussed.     

Human monoclonal rheumatoid factors: incidence of cross-reactions with tissue components and correlation with VH gene usage.

Human monoclonal antibodies with rheumatoid factor (RF) activity, derived from lymphocytes from the synovial tissue of rheumatoid arthritis (RA) patients and the peripheral blood of healthy individuals were examined for cross-reactivity with tissue and cellular antigens. The majority of IgM RF from RA patients (68%) showed reactivity with at least one component, and were frequently multispecific. A very significantly smaller proportion (28%) of the RF derived from healthy individuals demonstrated reactivities against tissue/cellular antigens (P = 0.004). RF from RA patients most commonly reacted with gastric glands (61%), nuclei (50%) and smooth muscle (50%), whereas RF from healthy donors most commonly reacted with gastric glands (20%), smooth muscle (16%), endothelium (16%) and glomeruli (16%). The most striking difference between the two groups was the reactivity with nuclear components, demonstrated by 50% of the RA RF, but by none of the healthy donor RF. As the two groups of antibodies share the same specificity for IgG Fc, but show differences in variable region segment usage, we investigated the relationship between VH gene usage and tissue/cell cross-reactivity using these antibodies and anti-blood group antibodies. Antibodies using VH3 or VH4 gene segments showed a very significantly greater frequency of tissue/cell reactions than those using VH1 (P = 0.0095 and 0.0004 respectively).     

Re-evaluation of ELISA and latex agglutination test for rheumatoid factor detection in the diagnosis of rheumatoid arthritis.

An indirect ELISA for the determination of each isotype (IgM, IgG, IgA, IgD, IgE) of rheumatoid factors (RF) was performed with sera obtained from 77 patients with either classical or definite rheumatoid arthritis (RA) and 319 controls, using rabbit IgG as the antigen. The results were compared with those of a commercial latex agglutination test, using denatured human gamma globulin as the antigen for rheumatoid factor determination. At the cut-off level at which positive results were found in less than 5% of normal controls, ELISA for IgM RF determination had sensitivity, specificity, efficiency, positive predictive value and negative predictive value of 46.75%, 98.12%, 88.13%, 85.71%, 88.41%, while those for IgA RF were 46.75%, 93.42%, 84.34%, 63.16%, 87.91% and for IgG RF were 59.74%, 92.16%, 85.86%, 64.78%, 90.46%, respectively. These indices by latex agglutination test were 83.11%, 93.73%, 91.67%, 76.19% and 95.83%, respectively. IgD RF titre greater than or equal to 1:5 was detected in 19/77 RA patients and 4/200 normal controls while IgE RF titre greater than or equal to 1:5 was detected only in 7/77 RA patients. Thus, ELISA did not appear to have any advantage over latex agglutination test for diagnosis of RA.     

The association of cryoglobulinaemia with nodules, vasculitis and fibrosing alveolitis in rheumatoid arthritis and their relationship to serum C1q binding activity and rheumatoid factor.

Two measurements of serum immune complexes, cryoglobulinaemia and 125I-C1q binding, have been performed in patients with severe rheumatoid arthritis (RA) and compared with normal levels. Cryoglobulinaemia was present in 20 out of 28 patients (71%) with extra-articular disease (mean level 17 micrograms/ml) including nodules, digital vasculitis, cutaneous ulcers, rash, neuropathy, lung disease and scleritis, but in none of 32 patients with joint disease alone (uncomplicated RA) (mean level 3 micrograms/ml). Cryoglobulinaemia correlates with, but probably does not antedate, extra-articular disease, and may be useful in predicting morbidity and mortailty in this group of patients. In contrast, serum 125I-Clq binding was raised in patients with uncomplicated RA and those with extra-articular disease, although levels were higher in the latter group. Both tests showed a negative correlation with serum haemolytic complement and a positive correlation with IgM rheumatoid factor although there were some sera with raised levels of rheumatoid factor without cryoglobulinaemia. These results suggest that cryoglobulinaemia is a better test than Clq-binding for demonstrating the presence of circulating immune complexes involved in the pathogenesis of extra-articular lesions.     

IgA and IgM rheumatoid factors in serum, saliva and other secretions: relationship to immunoglobulin ratios in systemic sicca syndrome and rheumatoid arthritis.

Paired serum and saliva samples from seven patients with systemic sicca syndrome (SSS), 15 patients with rheumatoid arthritis and a positive Schirmer's test (RA+), 15 patients with rheumatoid arthritis and negative Schirmer's test (RA-) and 14 normal individuals were analysed for albumin and immunoglobulin concentration as well as IgA and IgM rheumatoid factor (RF) activity. Protein levels in saliva were higher in SSS and RA+ but, when corrected for serum concentration and salivary flow rate, only the IgG ratio remained significantly elevated in SSS (P less than 0.01) and RA- (P less than 0.05) and the IgM ratio was reduced in RA- (P less than 0.05) compared to controls. Although IgM RF activity in serum and saliva was strongly correlated (P less than 0.001) in all three patient groups, the activity in saliva was considerably lower than serum activity. In the two (RA) patients tested, IgM RF in saliva contained secretory component. Mean salivary IgA RF activity varied between 34% (RA-) and 84% (SSS) of serum activity and correlated with serum activity in SSS (P less than 0.001) and RA- (P less than 0.01). IgA RFs in saliva, but not in serum, contained secretory component. Additional demonstration of IgA RF activity in nasal and duodenal secretions in SSS may be related to involvement of the common mucosal immune system.     

Failure to demonstrate any interaction between polyclonal rheumatoid factors and IgG antinuclear antibodies or other IgG autoantibodies.

The autoantibody profile results from 750 randomly selected patients with rheumatoid factor (RF) and/or antinuclear antibody (ANA) positive tests were retrospectively analysed in order to discover if there was any evidence to show that the presence of polyclonal rheumatoid factors affects the incidence and titre of IgG-ANA in these patients. The incidence of IgG-ANA in the RF-positive group (34.4%) was significantly greater than that found in the RF-negative groups (19.6%) (P < 0.001), and there was no significant difference between the mean IgG-ANA titres of the two groups (P = 0.987). The possibility that the presence of IgM-RF in serum might be responsible for the inhibition of IgG-ANA was examined by treating the sera of selected patients who were RF-positive but IgG-ANA-negative with the dissociating agent D-penicillamine (DP). After treatment, IgG-ANA could not be detected in any of the sera. Similar studies were carried out to ascertain if there was a masking effect by RF on two other IgG autoantibodies, anti-keratin antibody (AKA) and gastric parietal cell antibody (GPCA). There was no evidence from these studies that the presence of RF affects the incidence of either AKA or GPCA. We conclude from these results that the presence of RF is not a significant factor controlling the incidence of either IgG-ANA or other IgG autoantibodies and that the routine treatment of RF-containing serum with a dissociating agent before testing for autoantibodies would be unnecessary.     

Clinical significance of serum IL-18 determination in rheumatoid arthritis

Interleukin (IL)-18 is a novel cytokine expressing at inflammatory lesion. In this study, to evaluate the clinical significance of IL-18 determination, we have examined serum IL-18, inflammation markers, sFas, and sFas-ligand concentrations in patients with rheumatoid arthritis(RA). Serum was obtained from 56 RA patients aged 35-74 years, 16 osteoarthritis (OA) patients aged 36-78 years and 178 healthy subjects aged 20-72 years and IL-18 was measured by ELISA. Serum IL-18 concentrations in RA (240.1 +/- 15.6 pg/ml, mean +/- SE) were significantly higher than OA (151.8 +/- 12.7 pg/ml, p < 0.005) and healthy controls(141.5 +/- 26.1 pg/ml, p < 0.001). Serum IL-18 levels were significantly increased in II to IV stages of RA (stage II; 218.6 +/- 31.2 pg/ml, stage III; 258.7 +/- 38.4 pg/ml, stage IV; 231.6 +/- 13.1 pg/ml) than those in OA. Furthermore, a positive correlation was observed between serum IL-18 concentration and serum Fas level in patients with RA (r = 0.472), whereas there was no significant correlation between serum IL-18 and sFas-ligand or other inflammatory markers (CRP, RF, CA-RF, IL-6, and IL-8). The present study showed that serum IL-18 level increased in RA, but it is unknown how IL-18 is involved in the pathogenesis of RA. Further study will be necessary to clarify the role of IL-18 in RA.     

Correlative studies of rheumatoid factors and anti-viral antibodies in patients with rheumatoid arthritis.

An analysis of the relationship between the immune response to ubiquitous herpes family viruses, namely Epstein-Barr virus (EBV), cytomegalovirus (CMV), and varicella-zoster virus (VZV) and the presence of rheumatoid factors (RF), which are autoantibodies characteristic of patients with rheumatoid arthritis (RA), was conducted. Antibody profiles (RF, anti-viral antibodies) were monitored in the serum of the RA patients, and in normal individuals. No patient was found to have circulating RF in the absence of anti-viral antibodies. When the patients and normal controls were subdivided according to the presence of serum RF, it was found that when RF were present, the frequency of anti-CMV antibodies, but not anti-EBV or anti-VZV antibodies, was significantly higher (P = 0.02) when compared with RF-negative individuals. The titres of anti-CMV but not anti-VZV antibodies were found to increase in the RA patients with disease duration. To see if these viruses could stimulate RF production in vitro, peripheral blood mononuclear cells (PBMC) isolated from the patients and normal controls were stimulated with viral antigens. PBMC from normal controls, but not from RA patients, appeared to be responsive to viral antigen stimulation and produced RF. These data suggest that the immune response to CMV, to a greater extent than to EBV or VZV, correlates with the presence of RF.     

Raising rheumatoid factor cutoff helps distinguish rheumatoid arthritis

The presence of rheumatoid factor (RF) is one of the clinical criteria for the diagnosis of rheumatoid arthritis (RA). The cutoff point of RF assays is usually based on a reference level obtained from normal subjects in the same population as the patients. We evaluated 63 rheumatoid arthritis (RA), 25 other arthritis patients and 110 blood donors. Their rheumatoid factors (RF) ranged from < 9.9 to 2,264, < 9.9 to 262, and < 9.9 to 66 mIU/ml, respectively. The sensitivity at different cutoff points of 15, 20, and 25 mIU/ml was 92.1%, 90.5%, and 88.9%, respectively. The specificity at the same cutoff points was 81.5%, 84.4%, and 85.2%, respectively. Having minimally sacrificed the sensitivity, we recommend using a higher RF cutoff to increase specificity.     

A quantitative assay for IgA rheumatoid factor

We have developed a solid-phase radioimmunoassay capable of detecting nanogram quantities of human IgA rheumatoid factor (RF) in biological fluids. Human IgM RF, IgG RF, IgG, IgA, IgM and whole serum did not significantly interfere with the IgA RF assay. Patients with sero-positive rheumatoid arthritis (RA) had significantly higher concentrations of IgA RF than sero-negative RA patients or healthy adult controls. Concentrations of IgA RF in paired sera and synovial fluids from sero-positive RA patients were comparable. Levels of IgA RF demonstrated a moderately good correlation with levels of IgM RF in sero-positive RA sera (r = 0.673). However, the ratio of IgA RF concentration to IgM RF concentration in sero-positive RA sera varied widely.     

Serum autoantibodies profile and increased levels of circulating intercellular adhesion molecule-1: a reflection of the immunologically mediated systemic vasculopathy in rheumatic diseases?

The clinical manifestation of systemic vasculitis may be postulated as a consequence of immune response abnormalities in the course of connective tissue diseases (CTD). The aim of this study was to elucidate the significance of the different autoantibodies and soluble intercellular adhesion molecule 1 (sICAM-1) being shed into the circulation in the diagnosis of vasculitis in rheumatic diseases. Sera of 86 patients with rheumatic diseases (54 with rheumatoid arthritis (RA) and 32 with CTD) were analyzed for the concentrations of sICAM-1 levels by the enzyme-linked immunosorbent assay (ELISA). Control sera were obtained from 30 healthy individuals. Anti-nuclear antibodies (ANA), anti-double-stranded DNA (anti-dsDNA) antibodies and anti-proteinase 3 (PR-3) antibodies (cytoplasmic specific anti-neutrophil cytoplasmic autoantibodies, cANCA) were assessed by the ELISA method. Fifty out of the 86 patients had systemic lesions. A pathological picture of the vascular loop under nailfold capillary microscopy was found in 84 patients. In 19 patients the microvascular changes were advanced, in 35 moderate and in 30 mild. All patients with articular manifestations had pathological changes under capillary microscopy. Patients with advanced changes under capillary microscopy had longer disease durations than patients with a mild intensity of vasculitis. The serum concentrations of sICAM-1 were significantly increased in RA and CTD patients compared with 30 controls (in both cases p<0.001). Moreover, RA and CTD patients with systemic vasculitis showed significantly higher levels of sICAM-1 than those without vascular involvement (p<0.001 and p<0.005 respectively). ANA were observed in significantly elevated concentration among RA and CTD patients with the systemic damage compared with patients without organ injury (p<0.001 and p<0.05 respectively). Also, cANCA levels were two-fold higher, but only among CTD patients with systemic damage (p<0.05). Serum concentrations of sICAM-1 were elevated in the patients showing the presence of ANA antibodies (p<0.05). Significant correlations between ANA level and disease duration and hemoglobin concentration were observed. The concentrations of cANCA correlated with those of rheumatoid factor and of dsDNA with patient age. We conclude that systemic lesions in the course of RA and CTD are accompanied by the microvascular injury observed under nailfold capillary microscopy. Our data suggest that sICAM-1, ANA and cANCA serum levels may reflect the extent of the vascular involvement in RA and CTD patients.     

类风湿关节炎患者血清中高密度脂蛋白的水平检测与意义

目的分析类风湿关节炎(Rheumatoid Arthritis,RA)患者体内高密度脂蛋白(HDL-C)的水平与疾病活动度的关系。方法选取RA患者158例,化学沉淀法检测患者血清中HDL-C水平,同时收集患者的其它临床指标,包括C反应蛋白(CRP)、红细胞沉降率(ESR)、类风湿因子(RF)及抗环瓜氨酸肽(CCP)抗体。通过查体评估患者的压痛关节数(Tender joint count,TJC),肿胀关节数(Swollen joint count,SJC),视觉疼痛评分(Visual analogue scale,VAS),并通过标准公式根据ESR来评价患者的28个关节疾病活动度(Disease activity score in 28 jointsusing ESR,DAS28-ESR)水平。结果在总体RA患者中,其HDL-C水平与其CRP,ESR水平呈负相关,女性患者HDLC水平较男性患者高,复治患者HDL-C水平较初治患者高。对于初治患者,HDL-C与患者的炎症水平呈负相关,血清学阳性的患者HDL-C水平较血清学阴性的患者高,对于女性血清学阳性的患者而言,HDL-C水平与疾病活动度呈负相关。结论HDL-C水平对于RA疾病具有保护作用。     

The distinct subgroup of patients with rheumatoid arthritis shown by Ig G3-reactive rheumatoid factor

The reactivity of rheumatoid factor (RF) with immunoglobulins of the IgG3 subclass was examined in 49 patients with rheumatoid arthritis (RA) using two types of IgG3 myeloma (routine and IgG3m-15 allotype). Among 49 patients, serum from eight cases showed positive reactivity with both types of IgG3 myeloma by radio-immunoassay (RIA). The isotype of IgG3-reactive RF was not specific; it belonged to the IgM class as well as the IgG subclasses IgG1, IgG2 and IgG4. The patients with IgG3-reactive RF belonged to the clinically-severe classification of RA, having a high erythrocyte sedimentation rate (ESR), high titre in the RA hemagglutination (RAHA) test, and above all they had low levels of complement. Generally, it is concluded that patients with IgG3-reactive RF have serious arthritis and that IgG3-reactive RF might play an important role in the inflammatory process. Furthermore, it was also shown that the RF-reactive site was not associated with the protein-A binding site of IgG3, since RF reacting with IgG3m-15 reacted similarly with routine IgG3, regardless of the difference of the protein-A binding activity. This was confirmed by adding protein-A to the reaction of RF and IgG3m-15 which binds with protein-A. This suggests that the actual reactive site of RF is different to the site that binds protein-A.     

Soluble Intercellular Adhesion Molecule-1 (ICAM-1) Antigen in Patients with Rheumatoid Arthritis

Intercellular adhesion molecule-1 (ICAM-1), a member of the immunoglobulin supergene family, is known to play an important role in inflammatory diseases. Using a previously developed enzyme-linked immunosorbent assay (ELISA) with two monoclonal antibodies (MoAbs) against human ICAM-1, levels of soluble ICAM-1 (sICAM-1) were measured in sera from patients with collagen diseases and in synovial fluids (SF) from patients with rheumatoid arthritis (RA). Although the results did not demonstrate that RA and other collagen diseases, as a group, had significantly higher levels of sICAM-1 in sera as compared with healthy controls, 21 of 138 cases (15%) with collagen diseases and 11 out of 57 patients (19%) with RA clearly showed higher levels of sICAM-1 in the sera. Comparisons between RA patients of radiological stages I and II and between stage I and other stages showed significantly higher levels of sICAM-1 in the sera of patients in the latter stages. RA patients with vasculitis and/or pneumonitis showed significantly higher levels of sICAM-1 than those without vasculitis or pneumonitis. Significant correlations were demonstrated between sICAM-1 and the factors IgG-RF, IgM-RF, erythrocyte sedimentation rate (ESR) and TNF-α in sera of RA patients. In addition, it was noted that the levels of sICAM-1 in SF were as high as those in the sera of patients with RA.     

IL-22在类风湿关节炎中的表达及临床意义

目的：探讨RA患者IL-22的表达水平并分析其临床意义。方法：流式细胞术检测RA患者（50例）、OA患者（15例）、健康对照组（15例）外周血及RA关节滑液Th22细胞所占比例,ELISA法检测血清及RA关节滑液中IL-22水平。检测RA患者疾病活动性、临床指标、骨破坏情况,分析其与IL-22水平相关性。两组间比较用t检验,相关性分析采用Pearson直线相关分析法,多组样本比较用Kruskal-Wallis H检验。结果：RA患者外周血中Th22细胞比例高于OA组（t=2.290,P=0.021）及健康对照组（t=2.524,P=0.015）;RA患者血清IL-22水平高于OA患者（t=2.560,P=0.014）及健康对照组（t=2.768,P=0.009）。RF阳性RA血清IL-22水平高于RF阴性RA（t=2.322,P=0.035）。抗CCP抗体阳性RA血清IL-22水平高于抗CCP抗体阴性RA（t=2.504,P=0.015）。RA血清IL-22水平与ESR、RF、DAS28评分呈正相关关系（r分别为0.312、0.314、0.332,P<0.05）。RA患者血清IL-22水平随骨侵蚀的加重呈递增趋势,X线不同分期之间差异有统计学意义（H=9.14, χ²_0.05（3）=7.81,H>χ²_0.05(3),P<0.05)。有关节积液RA患者血清IL-22水平高于无关节积液RA患者（t=2.587,P=0.012）,关节滑液IL-22水平高于血清（t=2.668,P=0.011）,与关节滑液Th22细胞比例无相关性（r=0.287,P=0.065）。结论：RA患者血清及关节滑液IL-22水平增高,与疾病活动性及骨破坏相关,可成为病情评估与骨破坏的指标。IL-22可能为RA治疗的新靶点。     

Dinucleotide repeat polymorphism in intron II of human Toll-like receptor 2 gene and susceptibility to rheumatoid arthritis

Human Toll-like receptors (TLRs) participate in innate immune response and signal the activation of adaptive immunity. The presence of a functional intronic polymorphism consisting of guanine-thymine repeats in TLR2 gene was recently reported. Here, we investigated a dinucleotide repeat polymorphism in intron II of TLR2 in Korean patients with rheumatoid arthritis (RA). The numbers of guanine-thymine [(GT)(n)] repeats in intron II of the TLR 2 gene were counted in 183 patients with RA and in 148 healthy controls, using the gene scanning technique. We classified alleles into two subclasses for further analysis, 12-16 GT repeats (S allele) and 17-28 repeats (L allele). By subgroup analysis, we also examined whether the S allele is associated with the presence of shared epitope (SE), rheumatoid factor (RF), joint erosion and extra-articular complications. S-allele frequency was significantly increased in patients with RA than in healthy controls [30.3% vs. 23.0%, P = 0.03, or 1.46, 95% confidence interval (CI) 1.03-2.07], and genotypes containing S alleles were more frequent in patients with RA than in healthy controls (54.4% vs. 46.5%. P = 0.04, or 1.57, 95% CI 1.01-2.42). A skewed S-allele distribution was not found to be related to the presence of SE. Subgroup analysis showed no genotypic or allele frequency differences between patients with/without RF, joint erosion, or extra-articular complications. Genotype containing shorter GT repeats in intron II of the TLR2 gene may confer susceptibility to RA in Koreans.     

Antibodies against macaque monoclonal immunoglobulin G in rheumatoid arthritis

The presence of rheumatoid factors (RF) in the serum of rheumatoid arthritis (RA) patients is commonly evidenced by agglutination tests: the Waaler-Rose assay, based on the use of human red blood cells (RBCs) coated with rabbit anti-RBC antibodies, and the latex test, which uses latex particles coated with denatured human immunoglobulin G (IgG). The aim of the present study was to characterize the RF able to agglutinate human RBCs coated with macaque antihuman RBC IgG antibodies secreted from macaque-mouse heterohybridomas (two from rhesus monkey and one from crab-eating macaque). Human RBCs coated with macaque monoclonal antibodies (MacMoAbs) were used for agglutination tests and these were carried out in parallel with standard tests (Waaler-Rose and latex agglutination tests) on sera from 82 RA patients, 86 patients with other forms of inflammatory chronic arthritis and 47 healthy human subjects. MacMoAb-coated RBCs identified RF in the sera of 66% patients with RA. By contrast, the frequency of positive sera in other inflammatory diseases was 5% and all 47 healthy controls were negative. Antimacaque IgG antibodies were found to be more specific for RF than standard tests, in the sera of patients with RA.