HLA antigens and seronegative rheumatoid arthritis

When Autoantibodies Are Missing: The Challenge of Seronegative Rheumatoid Arthritis

Seronegative rheumatoid arthritis (SNRA) is characterized by the absence of both rheumatoid factor (RF) and antibodies against the cyclic citrullinated protein (ACPA) in serum. However, the differences between the two forms of RA are more complex and have not yet been definitively characterized. Several lines of evidences support the idea that there are specific elements of the two forms, including genetic background, epidemiology, pathogenesis, severity of progression over time, and response to therapy. Clinical features that may differentiate SNRA from SPRA are also suggested by data obtained from classical radiology and newer imaging techniques. Although new evidence seems to provide additional help in differentiating the two forms of RA, their distinguishing features remain largely elusive. It should also be emphasized that the distinctive features of RA forms, if not properly recognized, can lead to the underdiagnosis of SNRA, potentially missing the period called the "window of opportunity" that is critical for early diagnosis, timely treatment, and better prognosis. This review aims to summarize the data provided in the scientific literature with the goal of helping clinicians diagnose SNRA as accurately as possible, with emphasis on the most recent findings available.

Mechanistic immunological based classification of rheumatoid arthritis

The classical autoimmunity paradigm in rheumatoid arthritis (RA) is strongly supported by immunogenetics suggesting follicular helper T-cell responses driving high titre specific autoantibodies that pre-dates disease onset. Using the immunological disease continuum model of inflammation against self with "pure" adaptive and innate immune disease at opposite boundaries, we propose a novel immune mechanistic classification describing the heterogeneity within RA. Mutations or SNPs in autoinflammatory genes including MEFV and NOD2 are linked to seronegative RA phenotypes including some so called palindromic RA cases. However, just as innate and adaptive immunity are closely functionally integrated, some ACPA+ RA cases have superimposed "autoinflammatory" features including abrupt onset attacks, severe attacks, self-limiting attacks, relevant autoinflammatory mutations or SNPs and therapeutic responses to autoinflammatory pathway therapies including colchicine and IL-1 pathway blockade. An emergent feature from this classification that non-destructive RA phenotypes, both innate and adaptive, have disease epicentres situated in the extracapsular tissues. This mixed innate and adaptive immunopathogenesis may be the key to understanding severe disease flares, resistant disease subsets that are unresponsive to standard therapy and for therapies that target the autoinflammatory component of disease that are not currently considered by expert therapeutic recommendations.

The role of antibodies in inflammatory arthritis

Inflammatory arthritis presents in a variety of diseases, from rheumatoid arthritis to hepatitis. Antibodies to autoantigens or to microbial constituents are commonly associated with these conditions. In some cases, the antibodies have diagnostic and prognostic relevance. It cannot as yet be determined definitively that any of them mediate joint damage, although the evidence from animal models indicates that this mechanism is likely. The purpose of this article is to give an overview of the spectrum of antibodies found in a variety of inflammatory arthritides. The relevant animal models are also discussed.

Gold salts, D-penicillamine and allopurinol

Gold salts have been used in the treatment of patients with rheumatoid arthritis since 1927 [1]. After a controlled study, the Empire Rheumatism Council [2], confirmed the effectiveness of gold salts for the treatment of rheumatoid arthritis. Even today, chrysotherapy has remained one of the major therapeutic modalities in the second line treatment of progressive rheumatoid arthritis. Gold salts are also used in the treatment of pemphigus vulgaris [3] and bronchial asthma [4]. Before the introduction of an orally administered gold compound, auranofin (triethylphosphine gold tetra-acetyl glycopyranoside), to clinical use [5-7], parenterally administered gold salts, such as sodium aurothiomalate and gold thioglucose comprised chrysotherapy. The frequency and severity of the side effects for patients treated with parenteral gold versus those given oral gold preparations are significantly different [8-10]. With introduction of newer parental DMARDs, toxicity has been reduced using combination therapy [10a, 10b].

Shared-epitope HLA-DRB1 alleles and sex ratio in Italian patients with rheumatoid arthritis

OBJECTIVE

To investigate the association between the HLA-DRB1 alleles sharing the epitope (Q/R)(K/R)RAA and rheumatoid arthritis (RA) in a large sample of Italian patients (N = 264) recruited from a single centre over the last 5 years.

METHODS

Patients' classification according to the ACR criteria. DNA typing of HLA-DRB1 alleles by conventional polymerase chain reaction sequence specific oligonucleotide probing techniques.

RESULTS

Low-resolution DRB1 "generic" typing showed a significantly higher frequency of DR4+ RA patients as compared to normal controls. Both DR1 and DR10 specificities were over-represented in our patients, but neither reached the statistically significant P level of 0.05 after Bonferroni's correction. However, direct search of Q(K/R)RAA epitopes, which are present in most DR4+ and DRl+ samples, demonstrated that these motifs were found at increased frequencies in RA patients. Stratification according to gender did not show differences in the proportion of disease-associated HLA alleles.

CONCLUSIONS

Our study confirms the association of HLA-DR4, and -DR1 alleles, and more generally speaking of the shared epitopes Q(K/R)RAA, with disease susceptibility in Italian patients.

Tumor necrosis factor markers show sex-influenced association with rheumatoid arthritis

OBJECTIVE

The observation that not all shared-epitope genotypes confer the same risk suggests that a second HLA-region locus may confer risk. Tumor necrosis factor alpha (TNFgamma) is a possible candidate. We examined TNFalpha for sex influences on HLA-associated risk for rheumatoid arthritis (RA).

METHODS

DRB1 and TNF microsatellite typing of 297 Caucasian RA patients (132 men, 165 women) and 267 Caucasian controls was performed.

RESULTS

The TNFab microsatellite haplotype distribution differed among the male RA, female RA, and control groups (P < 0.01); the difference was largely an excess of TNFa2b1 haplotypes in the male RA group. However, this did not simply reflect an excess of shared-epitope haplotypes bearing TNFa2b1. In RA, not all shared-epitope-bearing haplotypes had the same TNFab. The *0401-bearing haplotypes commonly had TNFa6b5, TNFa2b1, TNFa10b4, and TNFa11b4, while the *0404-bearing haplotypes had TNFa11b4. In the female RA group, TNFa2b1 was most often on *0401-bearing haplotypes. In the male RA group, there was a surprise: TNFa2b1 was often on HLA haplotypes without shared-epitope DRB1 alleles. To estimate the relative strength of associated HLA markers, we performed logistic regression analyses stratified by sex and controlling for a potential confounder, age at disease onset. Among women, TNFa2b3 favored RA (odds ratio 1.932, P < 0.05) while TNFa6b5 was protective (odds ratio 0.522, P < 0.05). Among males, TNFa2b1 and TNFa11b4 conferred elevated odds ratios (2.58 and 1.681, respectively, P < 0.05). However, the odds ratios for TNFa2b1 in men and TNFa2b3 in women were generally well below those for RA-associated DRB1 markers (for example, DRB1*0401 3.553 in male RA patients and 6.991 in female RA patients).

CONCLUSION

Certain TNFab-bearing HLA haplotypes modify RA risk in a manner influenced by sex but independent of DRB1, particularly TNFa2b1 in men.

HLA-DR expression of synovium and correlation with clinical features of patients with rheumatoid arthritis

To investigate whether the expression of human leukocyte antigen-DR (HLA-DR) in synovial tissues obtained at synovectomy contributes to the clinical features of patients with rheumatoid arthritis (RA), immunohistochemical analysis was performed to determine the intensity and pattern of HLA-DR expression in synovial tissue from 96 patients with RA. The clinical features before and 1 year after the synovectomy were investigated. At the time of the surgery, duration of morning stiffness was associated with the degree of HLA-DR expression in synovial lining layer, and this synovial lining expression of HLA-DR was more frequently observed in elbow and wrist joints than in knee joint. In patients who underwent knee synovectomy, erythrocyte sedimentation rate and C-reactive protein level one year after the surgery were significantly higher in the patients with intense expression of HLA-DR in the synovial lining. Our findings showed that the expression of HLA-DR in the synovial lining contributes to several clinical features, and the expression in large joint such as knee may related with disease course of patients with RA.

The role of HLA-DR-DR and HLA-DR-DP interactions in genetic susceptibility to rheumatoid arthritis

In order to analyze the relationships between the DR and DP loci in the genetic susceptibility to RA, HLA-DRB1 and -DPB1 polymorphism was studied in 155 RA patients compared to 150 controls, using a reverse dot-blot analysis. Our data were consistent with the involvement of the amino acid in position 71 of the third hypervariable region of the DR beta 1 chain in susceptibility to the disease. The higher risk for RA was observed in patients who carried the association of a lysine (K), characterizing the DRB1* 0401 susceptibility allele, with an arginine (R), observed in all the other DRB1* susceptibility alleles (21.9% vs 0.6%, p(c) < 10(-6), OR = 42) In the absence of arginine, the presence of lysine was still associated with the disease (33% vs 19%, p(c) < 0.03, OR = 2). In contrast, in the absence of lysine, the frequency of arginine in position 71 was similar in patients and controls (30% vs 26%, p = NS). On another hand, the analysis of the HLA-DPB1 locus showed that the DPB1 *0401 allele frequency was significantly increased in the RA patient group (n = 47) who expressed only arginine at the position 71 of the beta 1 chain (82% vs 56% in controls, p < 0.008), with role of HLA-DR--DR and -DR-DP interactions in the genetic susceptibility to RA.

The specificity of the anti-Proteus antibody response in tissue-typed rheumatoid arthritis (RA) patients from Brest

Anti-Proteus mirabilis antibody titres were found to be elevated in 50 active tissue-typed French rheumatoid arthritis (RA) patients from Brest when compared to 49 healthy French controls using enzyme-linked immunosorbent assay (ELISA; P < 0.001) and indirect immunofluorescence assay (IIFA; P < 0.001). However, there was no significant elevation in antibody titres against Escherichia coli or Salmonella typhimurium in the RA patients compared to the controls when measured by ELISA. Serum levels of C-reactive protein (CRP) were also found to be significantly higher in RA patients when compared to healthy control subjects (P < 0.001). These results suggest that P. mirabilis may play an important and specific role in the triggering and persistence of RA.

Elderly-onset rheumatoid arthritis

Elderly-onset rheumatoid arthritis (EORA), defined as rheumatoid arthritis (RA) with onset at age 60 years or over, differs slightly at presentation from younger-onset RA (YORA) by a more equal gender distribution, a higher frequency of acute onset with systemic features, more frequent involvement of the shoulder, and higher disease activity. Longitudinal studies have showed more disease activity, radiographic damage, and functional decline in patients with EORA than in those with YORA. These differences were only found in seropositive patients. Seropositive EORA was reported to be associated with HLA-DR4, in contrast to seronegative EORA. Possible heterogeneity in the pathogenesis of seronegative EORA is supported by the recognition of subsets that overlap with the clinical manifestations of other syndromes such as polymyalgia rheumatica and remitting seronegative symmetrical synovitis with pitting edema. In addition, crystal-induced arthritis and inflammatory osteoarthritis may be difficult to distinguish from EORA. The efficacy and toxicity of second-line drugs is similar in both age groups, but in the elderly caution is needed with the use of nonsteroidal antiinflammatory drugs and prednisone.

The prognostic value of HLA DR4 and B27 antigens in early rheumatoid arthritis

The prognostic significance of HLA DR4 and B27 antigens was investigated in a 3-year follow-up of 87 patients with early rheumatoid arthritis (RA). The frequencies of DR1, DR4 and also of B27 were increased and the frequencies of DR2, DR3 and DR7 decreased compared with the normal Finnish population. During the follow-up with antirheumatic treatment, a similar improvement in clinical variables and laboratory measure assessing disease activity was found in both DR4-positive and DR4-negative RA patients. Despite clinical improvement a fast radiological progression in peripheral joints was observed but the presence of DR4 or B27 had no impact on the progression of joint damage. In some patients cervical changes developed early in the course of RA but were not related to DR4 or B27 positivity. The earlier observation of increased prevalence of HLA B27 in the Finnish RA patients was confirmed but the presence of B27 did not modify the clinical picture of RA.

HLA typing in families with multiple cases of rheumatoid arthritis

Thirty one white patients from 14 families with multiple cases of rheumatoid arthritis (RA) and 42 of their healthy relatives were completely HLA typed. In contrast with class I antigens, the class II antigens DR1 and DR4 were significantly more common in the patients than in a group of 200 healthy local white controls (DR1: 32% v 12%; DR4: 48% v 28%, in patients and controls respectively). Owing to the small number of cases the data from this study were combined with those of published reports. Examination of patients for DR1 and DR4 homozygosity and DR1/4 heterozygosity showed an increase of DR1 homozygous patients, which was not statistically significant. There was no striking deviation from random expectation in haplotype sharing of affected sib pairs. These results are compatible with a dominant influence of DR1 and DR4 in the mode of inheritance. The nearly random haplotype sharing and the molecular relation between DR1 and DR4 support the hypothesis of a direct influence of these antigens in the pathogenesis of RA. Only 68% of the patients in this study possessed either DR1 or DR4, possibly indicating a subtype of RA which is independent of HLA. Clinical and serological variables were measured and indicated no significant difference between DR1 (or DR4) positive and DR1 (or DR4) negative disease. In this small group of patients the clinical course of RA seemed to be determined mainly by other genetic or environmental factors.

DNA typing for class II HLA antigens with allele-specific or group-specific amplification. V. Typing for subsets of HLA-DR1 and DR'Br'

Three DRB1 alleles of the DR1 group including DRB1*0101, DRB1*0102, and DRB1*0103 are currently recognized. The first two of these are defined as HLA-DR1 by serologic typing and as either Dw1 or Dw20 by typing with T cells. DRB1*0103, previously called DR'Br' or DR'BON', is not detectable by serology. Little information exists about the population frequencies of DRB1*0102 and DRB1*0103. In the present study we have used the polymerase chain reaction (PCR) and allele-specific oligonucleotide probes to determine these alleles. To avoid cross-hybridization with other DRB genes having the same DNA sequences as those of the region to be analyzed, we performed group-specific PCR to amplify only DR1 DRB1 genes. This was accomplished using a 21-nucleotide-long primer, homologous to the first hypervariable region common to the DR1 DRB1 genes, and which under appropriate conditions amplified only DRB1 genes of the DR1 group. Five oligonucleotide probes, one matching the second hypervariable region, two spanning the third hypervariable region, and two covering codons 82 through 89, were used to determine the three alleles. DRB1*0101 (Dw1) was found to be the major type of DR1 in North American Caucasians. In North American black and Brazilian mestizo populations DRB1*0102 (Dw20) was more prevalent. DRB1*0103 (DR'Br') was detected in only six individuals in the present study.

HLA-DR alleles with naturally occurring amino acid substitutions and risk for development of rheumatoid arthritis

To determine the HLA-DR4 subtypes associated with rheumatoid arthritis (RA), we performed amplification of DR4 DRB1 genes by the polymerase chain reaction and dot-blots with oligonucleotide probes. In 52 HLA-DR4+ RA patients, Dw4 was the predominant subtype. This subtype was found in 45 of 52 patients (86.5%) compared with 33 of 59 DR4+ controls (55.9%; P less than 0.001). In the whole population, Dw4 also gave the highest relative risk for RA (RR = 5.31). Relative risk was also associated with DR1.1, the common white DR1 (Dw1) type, which has a third hypervariable region amino acid sequence similar to some forms of DR4 and has glycine at position 86. Variants of DR1 (DR1.2) or DR4 (Dw13.1, Dw14.1) with valine at position 86 appeared less able to confer risk for RA. Substitution of residues in the third hypervariable region of the first domain of DRB1 appeared to correlate with relative risk for RA. Among subjects having 0-1 amino acid substitutions, RA developed in 53%, whereas in subjects with 2-4 amino acid changes, RA was present in only 17.4% (P less than 0.00001). DQw7 (formerly DQw3.1) was slightly increased in DR4+ RA patients compared with controls, but a striking excess of Dw4,DQw7 homozygous patients was observed. The results suggest that DQw7 may have an additional effect, possibly with a recessive mechanism, since it was observed only in DR4 homozygous patients.

HLA-DR1 and DRw6 association in DR4-negative rheumatoid arthritis patients

This study of 110 seropositive rheumatoid arthritis (RA) patients confirms the significant association of susceptibility to RA with HLA-DR4 specificity (P less than 0.001). The DR1 frequency is elevated in the entire seropositive patient group, reaching marginal significance (P less than 0.025). The DR4-negative patients, however, have a much higher prevalence of DR1 (P less than 0.001). Surprisingly, the DRw6 specificity is significantly increased in the remaining DR4- and DR1-negative patients (P less than 0.01). These results demonstrate that RA is not associated with a single HLA-specificity, but to various degrees with DR4, DR1, and DRw6. These findings, and particularly the newly recognized association with DRw6, support the hypothesis that functionally equivalent shared epitopes or conformations on otherwise distinct MHC molecules may confer risk for developing RA.

Weak association between HLA-DR4 and rheumatoid arthritis in Chilean patients

Evidence has suggested a genetic link between the HLA-DR4 phenotype and rheumatoid arthritis (RA), particularly in its seropositive form. Such an association varies among different ethnic groups and remains controversial for seronegative patients. Data obtained for a group of 64 Chilean patients with RA (46 seropositive, 18 seronegative), as defined by the 1987 criteria of the American Rheumatism Association, and for 76 controls are reported here. The prevalence of HLA-DR4 and DR9 was significantly increased in the group of patients considered as a whole. The prevalence of HLA-DR4 was not significantly higher, however, when seronegative and seropositive patients were separately compared with controls. Also, it did not correlate with the severity of the disease within each subgroup of patients. On the other hand, HLA-DR9 showed a highly significant difference, not previously described, only for the seropositive patients in comparison with controls. The prevalence of DQ specificities showed no relevant differences among the groups. The HLA-DR4 serotype, therefore, is a weak marker for RA and does not differentiate any subgroup of patients in the Chilean group studied. This new finding, indicating an association between RA and the DR9 antigen, may be explained by the suggestion that susceptibility epitopes are shared among different DR molecules. This hypothesis might also account for the variation in the association of DR4 with RA.

Rheumatoid arthritis and Proteus: a possible aetiological association

The presence of specific anti-Proteus antibodies in active, rheumatoid arthritis (RA) patients, has been demonstrated by four different techniques: indirect bacterial agglutination, ELISA, Western blotting and immunofluorescence. Furthermore, anti-HLA-DR4 tissue typing sera have been shown to bind to Proteus microorganisms, thereby suggesting some molecular similarity or cross-reactivity between bacteria and HLA antigens. The concept is proposed that Proteus-reactive arthritis occurs during active phases of RA and tissue damage is mediated through immunological activity involving HLA antigens.

DR4 prevalence related to the age at disease onset in female patients with rheumatoid arthritis

The prevalence of HLA-DR4 in relation to age at disease onset was calculated in 226 consecutive female patients with definite or classical rheumatoid arthritis (RA). A slight increase in the prevalence of DR4 with age at RA onset was found. This appeared to be due to the low percentage of rheumatoid factor (RF) positivity in the youngest age groups; the DR4 prevalence in the RF positive patients was constant for all decades--that is, approximately 60%. A previously reported declining trend of DR4 prevalence in women with RA in relation to age of RA onset may be due to the disease heterogeneity of the patients included in that study.

HLA genes associated with rheumatoid arthritis. Identification of susceptibility alleles using specific oligonucleotide probes

We examined the association of individual HLA genes with rheumatoid arthritis (RA), using oligonucleotide probes that identified both DR4-associated and non-DR4-associated genes. Two distinct HLA-DR beta alleles (Dw4 and Dw14) were found in DR4+ RA patients compared with controls (Dw4 50% versus 17%; Dw14 35% versus 5%; total DR4 73% versus 30%), indicating that these 2 alleles are independent susceptibility genes. Remarkably, the majority of the DR4- RA patients also demonstrated a linear DNA sequence, apparently "shuffled" between different susceptibility alleles, identified with an oligonucleotide probe to a key portion of the Dw14 gene.

Associations of HLA-DR4 with rheumatoid factor and radiographic severity in rheumatoid arthritis

Possible associations between HLA-DR4 and laboratory, radiographic, joint count, functional, and demographic measures of clinical status were analyzed in 154 white patients with rheumatoid arthritis. Overall, 65 percent of the patients were HLA-DR4 positive, similar to other series. HLA-DR4 was associated significantly with the presence of rheumatoid factor and more severe radiographic changes. HLA-DR4 was not associated with significant differences in demographic, joint count, or functional measures of clinical status. HLA-DR1 was not associated significantly with differences in the presence of rheumatoid factor, radiographic changes, or other measures of clinical status. Selective associations of HLA-DR4 with rheumatoid factor and radiographic scores were more marked in men than in women. Patients who were putatively homozygous for HLA-DR4 were all seropositive and had more severe radiographic changes than patients who were heterozygous for HLA-DR4.

A DR4-associated DR-DQ haplotype is significantly associated with rheumatoid arthritis

Forty-three patients with seropositive, erosive rheumatoid arthritis (RA) and 24 members of 5 RA multicase families were studied for HLA class II gene polymorphism, using restriction fragment analysis with complementary DNA probes for DR beta and DQ beta chains. This method generates HLA-DR-DQ haplotypes that are highly correlated with HLA-DR serology. Thirty-five of the 43 RA patients (81%) were positive for one or for both of the DR4-associated DR-DQ haplotypes, 4.1 and 4.2. Among these patients, the 4.1 haplotype was found significantly more often than in DR4+ controls (P less than 0.01). The haplotype segment C3;B15;DR4 was present in all RA patients in 4 of the 5 families, and included the DR-DQ4.1 haplotype.

Relation between bone erosions and rheumatoid factor isotypes

Total rheumatoid factor (RF) activity and individual RF isotypes were measured in 62 patients with rheumatic diseases. Retrospective analysis of available x rays showed an association between IgA RF and the occurrence of periarticular bone erosions in hands. In contrast, IgG RF and IgM RF did not show any significant association with erosions. Furthermore, a close correlation was observed between the RF isotype levels in simultaneously drawn serum and synovial fluid samples. The possible significance of IgA RF in the pathogenesis of bone erosions is discussed.

HLA-DR4 and Gm(1,3;5,21) are associated with U1-nRNP antibody positive connective tissue disease

Patients with U1-nRNP antibodies (n = 35, 31 female, four male) were typed for HLA-A, -B, -C, and -DR antigens and IgG heavy chain allotypes G1m(1), -(2), -(3), G3m(5), and -(21). The patient group was clinically heterogeneous. Four met the American Rheumatism Association criteria for systemic lupus erythematosus, six for progressive scleroderma, and 14 for rheumatoid arthritis. Sicca syndrome was present in seven cases. Twenty three had overlapping features compatible with mixed connective tissue disease (MCTD). Healthy blood donors served as controls for HLA typing (n = 64), Gm typing (n = 228), or both (n = 56). Sixty six per cent of the patients with U1-nRNP antibodies were DR4 positive compared with 28% of the controls (relative risk = 4.9, p = 0.00053). The Gm(1,3;5,21) phenotype was found in 46% of the patients and 25% of the controls (relative risk = 2.47, p = 0.0247). Within the patient group Gm(1,3;5,21) was found only in DR4 positive individuals. The coincidence of HLA-DR4 and Gm(1,3;5,21) increases the relative risk values to 8.0 (compared with the group with neither risk factor). DR4 and Gm(1,3;5,21) primarily seem to be related to U1-nRNP antibody formation and not to disease expression. Patients with or without MCTD did not differ with respect to DR4 or Gm(1,3;5,21) frequency. Disease onset was earlier in patients with HLA-DR4/Gm(1,3;5,21) than in patients without both markers (mean 27.9 v 40.1 years; p less than 0.05).

HLA-DR versus HLA-B5-CREG antigens in rheumatoid arthritis (RA)

Thirty caucasian patients suffering from classic erosive rheumatoid arthritis (RA), with a condition persisting for more than 8 years, were examined together with 67 healthy control subjects with regard to associations to HLA-DR and HLA-B-CREG antigens (B5-, B8-, B12-, B16- and B27-CREG). We found a significant correlation of seropositive RA (SPRA) with HLA-DR4 (9/14 patients = 64% chi 2 = 11.8, p less than 0.05), and seronegative RA (SNRA) with B5-CREG antigens (14/16 patients = 88%, chi 2 = 7.8, p less than 0.05). This HLA locus-differing association of SPRA and SNRA could, in addition to the known differences in clinicophenomenological parameters, be additional proof of the independent entity of these two forms of illness.

Rheumatoid factor tests in the diagnosis and prediction of rheumatoid arthritis

Four assays of rheumatoid factor (RF) have been measured on serum from 213 individuals from 13 families containing at least two sufferers from classical or definite rheumatoid arthritis (RA). Families were not uniformly RF positive or negative, and there was no evidence that non-RA RF positivity was inherited. Four individuals developed definite RA over a two year period, showing that the family members were at increased risk of RA. IgG RF and latex RF assays predicted the RA in the four cases. An association of RF positivity in RA with DR4 was observed, but this may be related to disease severity.