Rheumatoid factor as predictor of response to treatment with anti-TNF alpha drugs in patients with rheumatoid arthritis: Results of a cohort study

We determined whether rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (ACPA) can predict remission or severe disability in rheumatoid arthritis (RA) patients treated with anti-tumor necrosis factor (TNF) alpha drugs.We performed a cohort study based on the clinical data from a referral center for the treatment of RA in Bogotá, Colombia, were included patients aged ≥18 years with diagnosis of RA with an active disease and for whom a treatment scheme was begun with anti-TNF alpha medication, with a minimum follow-up time of 12 months. Disease activity of Rheumatoid Arthritis was assessed through measurement of RF, ACPA, disease activity score (DAS28), and health assessment questionnaire (HAQ). We calculated the incidence rates (IRs) for remission and severe disability. We also calculated the incidence rate ratio (IRR) for each outcome by adjusting for possible confounders using the Poisson regression method. The hypothesis was tested with a P value of <.05. Statistical analysis was performed in Stata 15.We included 400 patients receiving an anti-TNF alpha agent. Median age was 60 years, and 322 patients were women (80.5%). RF was positive in 357 patients (89%), ACPA in 348 patients (87%), and co-positivity in 324 patients (81%). Median follow-up was 41 months (range, 12-79 months). The IR for remission was 23 per 100 person-years in RF-negative patients and 16 per 100 person-years in RF-positive patients. The adjusted IRR (age sex, treatment, and ACPA) was 1.51 (95%CI, 1.05-2.18). The IR for severe disability was 10.8 per 100 person-years in the RF-positive cohort and 2.3 per 100 person-years in the RF-negative cohort. The IRR adjusted for these factors was 4.37 (95%CI, 1.6-12). Co-positivity had a similar behavior to RF. No differences were recorded in the rates of remission or disability in ACPA-positive and ACPA-negative patients.Our findings suggest that remission is less frequent and severe disability more frequent in RF-positive patients treated with anti-TNF alpha agents than in RF-negative patients.

IL-17 patterns in synovium, serum and synovial fluid from treatment-naïve, early rheumatoid arthritis patients

BACKGROUND

There are actually becoming controversial data regarding the profiles of interleukin-17 (IL-17) in different pathogenical stages of rheumatoid arthritis (RA).

OBJECTIVES

To assessing the IL-17 patterns in synovium, serum and synovial fluid from treatment-naïve early RA patients and to identifying potential correlations with disease activity markers and with synovial histopathological profile.

MATERIALS AND METHODS

Serum samples from 30 treatment-naïve early RA patients were evaluated for C-reactive protein (CRP), erythrocytes sedimentation rate (ESR), rheumatoid factor (RF), anti-cyclic citrullinated peptide antibodies (anti-CCP). IL-17A levels were also assessed in serum and synovial fluid (SF). Disease activity score (DAS28) calculation was done for all patients. Control serum and SF samples were obtained from 29 patients with osteoarthritis (OA); control synovium specimens were obtained from eight patients with OA and during surgery for knee tear ligaments. Histopathological (Hp) score, immunohistochemical reactivity for IL-17 were also assessed in synovium of early RA patients and controls. Dependencies between serum and synovial profile of IL-17A and the other parameters were statistically tested.

RESULTS

In early RA patients, strong correlations of serum and SF IL-17A levels were found with ESR, CRP, RF, anti-CCP, Hp score and IL-17 synovial immunoreactivity; a good correlation was noted with DAS28 score. Also, strong correlation was noted between serum and SF IL-17A levels.

CONCLUSIONS

In early stages of untreated RA, simultaneous IL-17 assessment of serum, SF and synovium might be valuable in defining activity and predictive patterns, given that synovium is highly suggestive for an disease aggressivity and might express specific therapeutically targets.

[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.

Autoantibodies in silicosis patients and in silica-exposed individuals

The aim of this study was to evaluate the prevalence of autoantibodies in silica-exposed patients with and without silicosis and without any known rheumatic disease. We studied 61 males exposed to silica for a mean time of 12.2 +/- 10.2 years of exposure. A total of 72.1% (44/61) of them presented with pulmonary silicosis. As control group we included 62 healthy males. In all samples we screened for rheumatoid factor (latex agglutination), antinuclear antibodies (indirect immunofluorescence), anti Scl-70 (ELISA) and ANCA (indirect immunofluorescence technique). One patient (1.6%) of the silica group had weakly positive ANA (titer 1:80, centromeric pattern); one (1.6%) had atypical ANCA and seven patients (11.4%) presented positive rheumatoid factor (values range from 8 to 32 UI/ml). One control patient had a positive RF and none of them had positive ANA or ANCA. All patients and controls were negative for anti-Scl-70. The finding of positive RF was higher in the silica-exposed patients (p = 0.032; Fisher). All patients with positive RF had pulmonary silicosis. In the silica-exposed group we could not find a relationship between the presence of RF and age (p = 0.21; Mann-Whitney), smoking habits (p = 0.25; Fisher) but a positive relationship was found with exposure time to silica dust (p = 0.005; Mann-Whitney). We conclude that there was 11.4% prevalence of low titer RF in the silica-exposed patients without known rheumatic disease. RF was more common in patients with longer exposure to silica dust and appeared only in those with silicosis. The presence of ANA, Scl-70 and ANCA was the same as in the control population.

A longitudinal study of the relationship between galactosylation degree of IgG and rheumatoid factor titer and avidity during long-term immunization of rabbits with BSA

Although IgG with reduced content of galactose has been implicated as important in the autoimmune rheumatoid factor (RF) response in rheumatoid arthritis (RA), relatively little is known about the temporal relationship between RF and the degree of galactosylation of IgG in vivo. We established an experimental model for studying the dynamic association between changes in the relative extent of galactosylation of IgG antigen(s) and the main parameters of RF activity, such as the titer, specificity and functional affinity/avidity. Rabbits hyperimmunized with BSA were used for examining the influence of long-term antigenic stimulation on the galactosylation status of IgG and rheumatoid factor production. The results showed that the galactosylation profile of IgG varied during the humoral anti-BSA response in rabbits and that the accompanying RF response fluctuated in titer and binding avidity for differently galactosylated IgG. The immune complexes (IC) were found to be composed of differently galactosylated IgG differing in capacity to inhibit the agglutination activity of RF. Moreover, the ability of circulating RF to react avidly with rather small IC was associated with a lower content of galactose in complexed IgG. The results suggest that a certain dynamic relationship exists between the oligosaccharide moiety of IgG and the titer and avidity of RF during the normal anti-BSA response of rabbits.

IgM plays an important role in induction of collagen-induced arthritis

IgM is one major type of B cell receptor (BCR) expressed on most of the B cells from immature to mature stages. During normal B cell ontogeny, signals transduced through the IgM BCR play an important role in regulating B cell maturation and survival at multiple checkpoints. In addition, IgM BCR is also required for antigen-dependent differentiation and activation of B cells. However, whether IgM BCR-mediated signalling is important for the pathogenesis of autoimmune diseases remains elusive. Using IgM-deficient mice, we examined the effect of absence of IgM on the development of collagen-induced arthritis (CIA), an animal model of rheumatoid arthritis (RA). Compared to their wild-type littermates, IgM-deficient mice were either resistant to arthritis induction or developed significantly less severe arthritis. There was a significant decrease of autoantibody production in IgM-deficient mice, particularly IgG2a antibodies, which is believed to be pathogenic in CIA. Thus, although IgM(-/-) mice have relatively normal B cell development with IgD BCR replacing IgM BCR, the absence of IgM-mediated signals has a profound impact on the development of CIA, indicating that IgM plays an important role in the development and pathogenesis of autoimmune arthritis and IgM-mediated signalling is critical in the generation of pathogenic autoreactive antibodies.

Agonistic antibodies to Fas induce a breach in the endothelial lining of the liver and a breakdown in B cell tolerance

Liver disease can be associated with a breakdown in self-tolerance and the production of autoantibodies such as rheumatoid factors (RF), which bind to IgG. Here we investigated whether primary, non-infectious liver damage was sufficient to induce autoantibody production. We established a model of targeted liver damage induced by weekly sublethal injections of pro-apoptotic anti-Fas (CD95) antibodies. Liver damage, monitored by measurements of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, was minimal 1 week after anti-Fas injection. However, the sublethal Fas stimulation was sufficient to trigger significant haemorrhage in the liver, as assessed by Evans Blue dye leakage into the organ 5 h after anti-Fas antibody injection. We observed an induction of RF in response to the weekly injections of sublethal anti-Fas antibodies but not of isotype control antibodies, indicating a breakdown of self-tolerance induced by Fas engagement. RF induction was unlikely to be due to direct activation of B cells, as splenocytes stimulated with anti-Fas antibodies in vitro did not produce RF. These studies show that sublethal damage to the liver by Fas engagement leads to liver haemorrhage and is sufficient to trigger the breakdown of self-tolerance.

Rheumatoid factor induction in murine models of liver injury

Alcoholic liver disease and hepatitis C are associated with the production of autoantibodies such as rheumatoid factors (RF), which bind to IgG and can aid in host defence, but are also associated with pathological conditions such as rheumatoid arthritis. Because little is known about the role of RF in liver disease, we characterized the RF production that either occurred spontaneously in response to alcohol consumption or was induced by injection of an Escherichia coli glycolipoprotein in C57Bl/6 mice. Whereas severe liver damage was induced by carbon tetrachloride (CCl(4)), minimal damage was caused by chronic alcohol consumption. Liver damage was monitored by measurements of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Circulating RF was induced in response to chronic alcohol consumption; the latter probably involved Toll-like receptor ligation. In contrast, CCl(4)-induced damage was not associated with RF induction. However, concurrent treatment with an E. coli glycolipoprotein macromolecule that induced RF, protected against CCL(4)-induced liver damage as measured by a highly significant decrease (P = 0.008) at 4 weeks in AST and ALT. RF induced by E. coli glycolipoprotein correlated with 'protection' from liver damage, indicating that the RF autoimmune response does not necessarily exacerbate liver disease.

B-lymphocyte activating factor in systemic lupus erythematosus and rheumatoid arthritis in relation to autoantibody levels, disease measures and time

Overexpression of B-lymphocyte activating factor (BAFF) results in arthritis, glomerulonephritis and autoantibody formation in mice, but its role in human autoimmune disease is less obvious. Serum BAFF levels in patients with systemic lupus erythematosus (SLE) (n=42) and rheumatoid arthritis (RA) (n=60) were related to levels of disease activity, anti-dsDNA Ab, anti-ENA Ab, rheumatoid factor (RF) and anti-CCP Ab. BAFF levels were also followed over time in 19 SLE patients. BAFF levels correlated inversely with age, were higher in SLE than RA (median 2.7 versus 1.4 ng/mL, P < 0.01) and more SLE than RA patients had increased BAFF levels (57% versus 10%, P < or = 0.01). In SLE, BAFF levels correlated with SLEDAI scores but not with anti-dsDNA Ab levels. SLE patients with increased BAFF levels had higher SLEDAI and CRP levels. In RA, BAFF levels correlated weakly with anti-CCP levels (Rs 0.27, P = 0.07), but not with joint counts, ESR, CRP or RF levels. Longitudinal BAFF levels remained unaltered in two thirds of SLE patients and changes in BAFF levels were unrelated to disease flares. These findings suggest that BAFF stimulation of B-cells may contribute to SLE by other mechanisms than autoantibody production.

Modulation of autoimmunity by TLR9 in the chronic graft-vs-host model of systemic lupus erythematosus

Chronic graft-vs-host (cGVH) disease is induced in nonautoimmune mice by the transfer of alloreactive T cells that recognize foreign MHC class II. It closely resembles systemic lupus erythematosus, with antinuclear Abs and immune-mediated nephritis. Recent work has implicated TLRs, particularly TLR9, in the recognition of certain autoantigens in vitro and in vivo. To explore further the role of TLR9 in systemic autoimmunity, we induced cGVH disease in C57BL/6 (B6) mice lacking TLR9, including B6 mice expressing the anti-DNA-encoding IgH transgenes 3H9 or 56R (B6.3H9.TLR9(-/-), B6.56R.TLR9(-/-)). We found that cGVH disease caused breakdown of B cell tolerance to chromatin and DNA in TLR9(-/-) recipients of alloreactive cells, yet that nephritis was less severe and that some autoantibody titers were lower compared with B6-cGVH controls. Spleen lymphocyte analysis showed that cGVH disease strikingly depleted marginal zone B cells in B6 mice, but did not influence T cell subsets in either B6 or B6-TLR9(-/-) hosts. B6.56R.TLR9(-/-) mice had less spontaneous production of autoantibodies than B6.56R mice, but there were no significant differences between B6.56R and B6.56R.TLR9(-/-) postinduction of cGVH disease. Taken together, these results suggested that TLR9 may worsen some aspects of systemic autoimmunity while alleviating others.

Association of rheumatoid factor production with FcgammaRIIIa polymorphism in Taiwanese rheumatoid arthritis

Fcgamma receptors (FcgammaR) impact upon the development of inflammatory arthritis through immune complex stimulation and proinflammatory cytokine production. FcgammaRIIa, FcgammaRIotaIotaIotaa and FcRgammaIIIb polymorphisms were genotyped in 212 rheumatoid arthritis (RA) patients and 371 healthy control subjects using an allelic-specific polymerase chain reaction (PCR). No significant skewing in the distribution of FcgammaRIIa H/R131, FcgammaRIIIa F/V158 and FcgammaRIIIb NA1/NA2 was found between RA patients and healthy control subjects. However, a significant skewing distribution of the FcgammaRIIIa F/V158 polymorphism was observed between rheumatoid factor (RF)-positive versus RF-negative RA patients (P = 0.01). The low-affinity FcgammaRIIIa F158 allele seems to have a protective role in RF production, in comparison with the FcgammaRIIIa V158 allele (P = 0.004; OR = 0.485; 95% CI: 0.293-0.803). A high frequency of FcgammaRIIIa F/F158 was identified in RA patients with negative RF compared with RF-positive patients (for FF158 versus FV158 + VV158; P = 0.002; OR = 0.372; 95% CI: 0.194-0.713). In addition, no association was found between FcgammaRIIa H/R131, FcgammaRhoIIIa F/V158 and FcgammaRIIIb NA1/NA2 polymorphisms and other clinical parameters. The results of this study suggest that three activating FcgammaRs polymorphisms lack association with RA but FcgammaIIIa F/V158 polymorphism may influence RF production and IgG RF immune complex handling in Taiwanese RA patients.

Somatic mutations and activation-induced cytidine deaminase (AID) expression in established rheumatoid factor-producing lymphoblastoid cell line

Epstein-Barr virus (EBV) transforms human peripheral B cells into lymphoblastoid cell lines (LCLs), allowing the production of specific antibody-secreting cell lines. We and others have previously found that in contrast to peripheral blood B cells, EBV-transformed lymphoblastoid cell lines express the activation-induced cytidine deaminase (AID) gene. The opposite is true for the germinal center-specific BCL6 gene: it is expressed in adult peripheral blood B cells and is no longer expressed in LCLs. The present work extends our findings and shows that whereas AID expression is rapidly induced following EBV infection, BCL6 expression is gradually down-regulated and is fully extinguished in already established LCLs. The question of whether AID activation induces the process of somatic hypermutation (SHM) was investigated in adult-derived LCLs. It was found that the VH gene from the rheumatoid factor-producing RF LCL (derived from a rheumatoid arthritis patient), accumulated somatic point mutations in culture. Overall, nine unique mutations have accumulated in the rearranged VH gene since the generation of the RF cell line. Four additional intraclonal mutations were found among 10 cellular clones of the RF cells. One out of the four was in CDR1 and could be correlated with loss of antigen-binding activity in three out of the 10 clones. Altogether, these 13 mutations were preferentially targeted to the DGYW motifs and showed preference for CG nucleotides, indicating that they were AID-mediated. By contrast, mutations were not detected among 3700-4000 nucleotides each of the Vlambda, Cmu and GAPDH genes derived from the same RF cell cultures and the cellular clones. Our results thus show that AID may generate point mutations in the rearranged Ig VH during in vitro cell culture of adult-LCLs and that these mutations may be responsible, at least in part, for the known instability and occasional loss of antigen-binding activity of antibody-secreting LCLs.

Hypothesis: the humoral immune response to oral bacteria provides a stimulus for the development of rheumatoid arthritis

Rheumatoid arthritis (RA) and adult periodontitis share common pathogenetic mechanisms and immunologic and pathological findings. One oral pathogen strongly implicated in the pathogenesis of periodontal disease, Porphyromonas gingivalis, possesses a unique microbial enzyme, peptidylarginine deiminase (PAD), the human equivalent of which has been identified as a susceptibility factor for RA. We suggest that individuals predisposed to periodontal infection are exposed to antigens generated by PAD, with de-iminated fibrin as a likely candidate, which become systemic immunogens and lead to intraarticular inflammation. PAD engendered antigens lead to production of rheumatoid factor-containing immune complexes and provoke local inflammation, both in gingiva and synovium via Fc and C5a receptors.

Visualizing the Onset and Evolution of an Autoantibody Response in Systemic Autoimmunity

The onset of systemic autoimmunity is variable, making it difficult to identify early events. In this study, we show in rheumatoid factor (RF) Ig-transgenic autoimmune-prone mice that the appearance of RF B cells in blood signifies the onset of RF B cell activation in spleen, providing a novel window into the initiation of an autoantibody response. This allowed us to study the early and late phases of spontaneous induction of the B cell autoimmune response. Using this approach we showed that extensive Ab-forming cell generation in spleen, accompanied by somatic hypermutation, occurred despite the lack of an early germinal center response. The onset of the RF response correlated with the levels of IgG2a-containing immune complexes but not total IgG2a. By identifying the time of onset in individual mice, we were able to track progression of disease. We found remissions of RF Ab-forming cell production in some mice, suggesting that at the clonal level, chronic autoantibody responses are dynamic and episodic, much like acute pathogen responses. Surprisingly, there was little accumulation of long-lived plasma cells in bone marrow of mice with long-standing RF responses in spleen. These studies are among the first to define the early events of a spontaneous B cell autoimmune response.

Short-Lived Plasmablasts Dominate the Early Spontaneous Rheumatoid Factor Response: Differentiation Pathways, Hypermutating Cell Types, and Affinity Maturation Outside the Germinal Center

We used a newly validated approach to identify the initiation of an autoantibody response to identify the sites and cell differentiation pathways at early and late stages of the rheumatoid factor response. The autoimmune response is mainly comprised of rapidly turning over plasmablasts that, according to BrdU labeling, TUNEL, and hypermutation data, derive from an activated B cell precursor. Surprisingly, few long-lived plasma cells were generated. The response most likely initiates at the splenic T-B zone border and continues in the marginal sinus bridging channels. Both activated B cells and plasmablasts harbor V gene mutations; large numbers of mutations in mice with long-standing response indicate that despite the rapid turnover of responding cells, clones can persist for many weeks. These studies provide insights into the unique nature of an ongoing autoimmune response and may be a model for understanding the response to therapies such as B cell depletion.

[Intensity of the production of rheumatoid factor in patients with different degrees of sensitization to Borrelia garinii antigens]

The content of rheumatoid factor and the levels of IgA, IgM, IgG in patients with different degrees of sensitization to Borrelia garinii antigens were studied. The titer of rheumatoid factor was found to increase in accordance with the growth of the levels of anti-Borrelia antibodies. A rise in the concentration of serum immunoglobulins simultaneously with the development of Borrelia infection was registered. The mechanisms of autoimmunization are discussed, taking into account the known biological properties of the causative agent of Lyme disease.

A Critical Role for FcγRIIB in the Induction of Rheumatoid Factors

Rheumatoid factors (RF) are autoantibodies with specificity for the Fc portion of IgG, and IgG-containing immune complexes are likely to be the major source of RF autoantigens. Therefore, the activation of RF-producing B cells could be controlled specifically through recognition of IgG immune complexes by the low-affinity IgG FcR, FcgammaRIIB, a potent negative regulator of the BCR. To test this possibility, we determined the development of RF in C57BL/6 (B6) mice lacking FcgammaRIIB, in relation to the H2 haplotype, complement C3, and the Y-linked autoimmune acceleration (Yaa) mutation. FcgammaRIIB-null B6 mice displayed substantial anti-IgG2a RF activities in their sera, in addition to anti-DNA autoantibodies. Their RF and anti-DNA responses were linked to the H2(b) haplotype, but were suppressed almost completely by the H2(d) haplotype. Strikingly, the absence of C3 failed to modulate RF production, but strongly inhibited anti-DNA production. Furthermore, we observed that partial FcgammaRIIB deficiency (i.e., heterozygous level of FcgammaRIIB expression) was sufficient to induce the production of RF and anti-DNA autoantibodies in the presence of the Yaa mutation. In contrast to FcgammaRIIB, the deficiency in another BCR negative regulator, CD22, was unable to promote RF and anti-DNA autoimmune responses in B6 mice. Our results indicate that RF autoimmune responses are critically controlled by FcgammaRIIB, together with the H2(b) and Yaa gene, while C3 regulates positively and specifically anti-DNA, but not RF autoimmune responses.

Type I IFN Protects Against Murine Lupus

Both the type I (IFN-alpha beta) and type II (IFN-gamma) IFNs have been heavily implicated in the pathogenesis of systemic lupus erythematosus. To test the relative roles of these systems, congenic lupus-prone MRL/CD95(lpr/lpr) (MRL/lpr) mice lacking the type I IFN receptor (IFN-RI), type II IFN receptor (IFN-RII), or both, were derived. As expected, deficiency for IFN-RII protected MRL/lpr mice from the development of significant autoimmune-associated lymphadenopathy, autoantibodies, and renal disease. However, deficiency for the IFN-RI surprisingly worsened lymphoproliferation, autoantibody production, and end organ disease; animals doubly deficient for IFN-RI and IFN-RII developed an autoimmune phenotype intermediate between wild-type and IFN-RII-deficient animals, all correlating with an ability of type I IFN to suppress MRL B cell activation. Thus, type I IFNs protect against both the humoral and end organ autoimmune syndrome of MRL/lpr mice, independent of IFN-gamma. These findings warrant caution in the use of type I IFN antagonists in the treatment of autoimmune diseases and suggest further investigation into the interplay between the types I and II IFNs during the ontogeny of pathogenic autoantibodies.

Long-term intravenous administration of activated autologous lymphocytes for cancer patients does not induce antinuclear antibody and rheumatoid factor

The treatment of activated autologous lymphocyte can lead to a potent antitumor effect with destruction of autologous cancer cells, but potential adverse autoimmune effects due to destruction of autologous tissue must also be considered. This study was performed to evaluate whether administration of activated autologous lymphocytes induces autoimmune disease. Patients with advanced cancer, who underwent transfer therapy with activated autologous lymphocytes, were eligible for the study. Informed consent was obtained from 22 patients with hepatocelluler carcinoma, ovarian cancer, gastric cancer, etc. The variation in activated lymphocyte phenotypes was CD3+/HLA-DR+ activated T lymphocytes, 23% to 99%; including CD4+ cells, 4% to 65%; CD8+ cells, 10 to 91%; and CD16+/ICD56+ NK cells, 1% to 59%. Of the 22 patients, levels of antinuclear antibody and/or rheumatoid factor were above normal limits during the study in the following 5 patients: 3 patients showed no marked changes, one patient a slight decrease in rheumatoid factor and one patient a slight increase in antinuclear antibody during the course of treatment, respectively. The values for these markers of the other 17 patients varied within normal limits during treatment. Mild transient fever occurred in several patients as an adverse event. There were no other adverse reactions. No clinical symptoms or signs suggestive of autoimmune disease occurred in any patient during or after treatment. These results suggested that long-term administration of activated autologous lymphocytes does not induce autoimmune disease.

Autoimmunity and glomerulonephritis in mice with targeted deletion of the serum amyloid P component gene: SAP deficiency or strain combination?

Human serum amyloid P component (SAP) binds avidly to DNA, chromatin and apoptotic cells in vitro and in vivo. 129/Sv x C57BL/6 mice with targeted deletion of the SAP gene spontaneously develop antinuclear autoantibodies and immune complex glomerulonephritis. SAP-deficient animals, created by backcrossing the 129/Sv SAP gene deletion into pure line C57BL/6 mice and studied here for the first time, also spontaneously developed broad spectrum antinuclear autoimmunity and proliferative immune complex glomerulonephritis but without proteinuria, renal failure, or increased morbidity or mortality. Mice hemizygous for the SAP gene deletion had an intermediate autoimmune phenotype. Injected apoptotic cells and isolated chromatin were more immunogenic in SAP(-/-) mice than in wild-type mice. In contrast, SAP-deficient pure line 129/Sv mice did not produce significant autoantibodies either spontaneously or when immunized with extrinsic chromatin or apoptotic cells, indicating that loss of tolerance is markedly strain dependent. However, SAP deficiency in C57BL/6 mice only marginally affected plasma clearance of exogenous chromatin and had no effect on distribution of exogenous nucleosomes between the liver and kidneys, which were the only tissue sites of catabolism. Furthermore, transgenic expression of human SAP in the C57BL/6 SAP knockout mice did not abrogate the autoimmune phenotype. This may reflect the different binding affinities of mouse and human SAP for nuclear autoantigens and/or the heterologous nature of transgenic human SAP in the mouse. Alternatively, the autoimmunity may be independent of SAP deficiency and caused by expression of 129/Sv chromosome 1 genes in the C57BL/6 background.

Transgenic Expression of a Human Polyreactive Ig Expressed in Chronic Lymphocytic Leukemia Generates Memory-Type B Cells That Respond to Nonspecific Immune Activation

We generated transgenic mice, designated SMI, expressing unmutated H and L chain Ig genes encoding a low-affinity, polyreactive human (h)IgM/kappa rheumatoid factor. These animals were compared with control AB29 transgenic mice expressing a hIgM/kappa rheumatoid factor specific for human IgG, with no detectable reactivity with mouse proteins. SMI B cells expressed significantly lower levels of surface hIgM/kappa than did the B cells of AB29 mice, but still could be induced to proliferate by surface Ig cross-linking in vitro and could be deleted with anti-Id mAb in vivo. Transgene-expressing B cells of AB29 mice had a B-2 phenotype and were located in the primary follicle. In contrast, a relatively high proportion of hIgM-expressing B cells of SMI mice had the phenotype of B-1 B cells in the peritoneum or marginal zone B cells in the spleen, where they were located in the periarteriolar sheath, marginal zone, and interfollicular areas that typically are populated by memory-type B cells. Although the relative proportions of transgene-expressing B cells in both types of transgenic mice declined with aging, SMI mice experienced progressive increases in the serum levels of IgM transgene protein over time. Finally, SMI transgene-expressing B cells, but not AB29 transgene-expressing B cells, were induced to secrete Ab when cultured with alloreactive T cells. These results indicate that expression of polyreactive autoantibodies can allow for development of B cells that are neither deleted nor rendered anergic, but instead have a phenotype of memory-type or Ag-experienced B cells that respond to nonspecific immune activation.

Sjogren's syndrome presenting as remitting seronegative symmetric synovitis with pitting edema (RS3PE)

Remitting seronegative symmetric synovitis with pitting edema (RS3PE) syndrome is characterized by symmetrical and acute synovitis, pitting edema, the absence of rheumatoid factor, increased acute phase reactants, lack of bony erosions on radiography, and benign and short clinical course. Half of all patients with Sjogren's syndrome experience arthritis during the disease course. We here describe the first case of Sjogren's syndrome presenting as RS3PE. She had swelling in knees, ankles, and wrists. After then the swelling spread to her lower legs, feet, face, and both hands. She was admitted to another hospital and was suspected of lupus or rheumatoid arthritis. Three months later, she had dry mouth and had lower lip biopsy. She was admitted to this hospital due to development of swelling in face and lower legs for 3 days. On physical examination, she had pitting edema in both hands and feet dorsum. Laboratory test showed elevated erythrocyte sedimentation rate, positivity of rheumatoid factor, anti-nuclear antibody, and anti-Ro antibody. There was no erosion in the hands radiography. Schirmer's test and lip biopsy was compatible with Sjogren's syndrome. She was diagnosed RS3PE and Sjogren's syndrome. She was begun with prednisolone and her symptoms improved gradually.

Evolution of autoantibody responses via somatic hypermutation outside of germinal centers

Somatically mutated high-affinity autoantibodies are a hallmark of some autoimmune diseases, including systemic lupus erythematosus. It has long been presumed that germinal centers (GCs) are critical in autoantibody production, because they are the only sites currently believed to sustain a high rate of somatic hypermutation. Contrary to this idea, we found that splenic autoreactive B cells in autoimmune MRL.Fas(lpr) mice proliferated and underwent active somatic hypermutation at the T zone-red pulp border rather than in GCs. Our results implicate this region as an important site for hypermutation and the loss of B cell self-tolerance.

Smoking and disease severity in rheumatoid arthritis: association with polymorphism at the glutathione S-transferase M1 locus

OBJECTIVE

To determine whether the relationship between smoking and disease severity in women with rheumatoid arthritis (RA) is associated with polymorphism at the glutathione S-transferase (GST) M1 locus.

METHODS

Genotyping for GSTM1 was carried out using polymerase chain reaction methodology on 164 women with established RA. Smoking history was obtained on each patient. Radiographic damage was measured by the Larsen score, and functional outcome was assessed by the Health Assessment Questionnaire (HAQ). Data were analyzed by multiple regression analyses, with correction for age and disease duration.

RESULTS

Ever having smoked was associated with a worse radiographic and functional outcome than was never having smoked. Both past and current smoking were associated with increased disease severity. Stratification by GSTM1 status revealed that polymorphism at this locus affected the relationship between smoking and disease outcome measures. Patients who lacked the GSTM1 gene and had ever smoked had significantly higher Larsen and HAQ scores than did those who lacked the gene and had never smoked. Radiographic outcome in these patients was worse than that in patients who had the GSTM1 gene and who had smoked. The associations were not affected by correction for socioeconomic status. Rheumatoid factor (RF) production was found to be associated with smoking in only the GSTM1-null patients.

CONCLUSION

Our data suggest that disease outcome in female RA patients with a history of smoking is significantly worse than in those who have never smoked. Smoking was associated with the most severe disease in patients who carried the GSTM1-null polymorphism. This association may be due in part to a relationship between the GSTM1 polymorphism and RF production in smokers.

Differential requirements for induction of total immunoglobulin and physiological rheumatoid factor production by human peripheral blood B cells

Rheumatoid factors (RFs) are autoantibodies directed against the Fc part of IgG. Considerable evidence exists that there are two classes of RFs, pathological and physiological. Whereas pathological RFs are associated with disease, physiological RFs are considered to be a normal component of the immune response. RF(+) precursor B cells present as part of the B cell repertoire of healthy individuals are held responsible for the production of physiological RFs, which is a transient phenomenon with a clear correlation with an initiating stimulus such as immunization or exposure to an infection. Here we demonstrate a difference in the regulatory control of total Ig and RF production by peripheral blood (PB) B cells of both healthy controls (HC) and patients with rheumatoid arthritis (RA). Highly purified B cells from HC and patients with RA were cocultured with T cells stimulated with immobilized anti-CD3 mAb. Similar to IgM production, IgM-RF production was shown to be dependent on CD40 cross-linking. However, activation of PB B cells in the CD40 system in the presence of IL-2, IL-4, IL-10, combinations of these cytokines or supernatant of anti-CD3-stimulated T cells failed to induce detectable IgM-RF, whereas total IgM production was considerable. From these results we conclude that conditions to activate physiological RF(+) B cells require additional contact besides CD40--CD40L interactions between T and B cells. Since the requirements for RF production were similar using PB B cells from HC and patients with RA it is suggested that the regulatory properties of RF(+) precursors in the PB B cell compartment is equal among these groups. Together, these results indicate that conditions for the induction of total Ig and physiological RFs are different.

The lymphoid system in hepatitis C virus infection: autoimmunity, mixed cryoglobulinemia, and Overt B-cell malignancy

Like other hepatotropic viruses, hepatitis C virus (HCV) shares the property of inducing hepatocellular damage, possibly through induction of immune mechanisms that lead to hepatocellular necrosis. After infection of hepatocytes, and possibly other cells, humoral and cellular responses occur aimed at prevention of virus dissemination and elimination of infected cells. The early activated mechanisms include production of nonspecific and specific antibodies that represent the first-line of defense against invading foreign pathogens. As a consequence, circulating immune complexes are promptly formed, and antigen uptake and processing by specialized cells are enhanced. A major fraction of circulating immunoglobulins (Igs) are part of the spectrum of the so-called natural antibodies, which include anti-idiotypic antibodies and molecules with rheumatoid factor (RF) activity. They mainly belong to the IgM class, are polyclonal, and have no intrinsic pathogenetic potential. In 20-30% of HCV-infected patients, RFs share characteristics of high affinity molecules, are monoclonal in nature, and result in the production of cold-precipitating immune complexes and mixed cryoglobulinemia. It has been shown that anti-idiotypic antibodies and polyclonal and monoclonal RF molecules have the same cross-reactive idiotype, called WA, suggesting that their production is highly restricted. This strongly indicates that they arise from stimulation with the same antigen, likely HCV. It has also been speculated that B-1 (CD5+) and B-2 (CD5-) B-cell subsets, which use a limited number of VH germline genes, underlie the production of low-affinity polyclonal and high-affinity monoclonal antibodies, respectively. The persistent production of monoclonal RF molecules implies the existence of a further mechanism capable of restricting the reactivity and reflects a distinct selection of a cell population that can be maintained throughout life because they are continuously exposed to antigen pressure. Either polyclonal or monoclonal profiles of B-cell expansion are demonstrable in the liver of most HCV-infected patients. The occurrence of B-cell clonal expansion is strictly related to intrahepatic production of RF molecules, and this suggests that liver is a microenvironment, other than lymphoid tissue, in which a germinal centerlike reaction is induced. The frequent detection of oligoclonal B-cell expansion may, indeed, represent a key pathobiologic feature that sustains nonmalignant B-cell lymphoproliferation. The preferential expansion of one clone would in turn lead to a monoclonal pattern that could favor stochastic oncogenic events. It can be postulated that HCV is the stimulus not only for the apparent benign lymphoproliferative process underlying a wide spectrum of clinical features, but also for the progression to frank lymphoid malignancy in a subgroup of patients. Current data indicate a higher prevalence of overt B-cell non-Hodgkin's lymphoma in HCV-infected patients, especially in some geographic areas.

Anti-CD69 autoantibodies cross-react with low density lipoprotein receptor-related protein 2 in systemic autoimmune diseases

We investigated whether autoantibodies to CD69, one of the earliest markers of lymphocyte activation, exist in the sera of patients with systemic autoimmune disease. Serum samples were obtained from patients with rheumatoid arthritis (RA), systemic lupus erythematosus, and Behcet's disease, and were tested for the presence of anti-CD69 autoantibodies by ELISA and Western blotting using rCD69 fusion proteins. IgG-type autoantibodies to CD69 were detected in the sera of 38.3% of the RA patients, 14.5% of the systemic lupus erythematosus patients, and 4.0% of the patients with Behcet's disease. Among those with RA, the anti-CD69 autoantibody-positive patients had a higher serum level of rheumatoid factors and a more accelerated erythrocyte sedimentation rate than the anti-CD69 autoantibody-negative patients. Further, the predominant epitope on the CD69 molecule to which most of the anti-CD69 autoantibody-positive serum samples exclusively reacted, was mapped at the C terminus of CD69. Of interest, this epitope is homologous to a stretch of amino acids in the protein sequence of low-density lipoprotein receptor-related protein 2 (LRP2), which is a receptor for multiple ligands including beta-very low density lipoprotein and is also an autoantigen responsible for Heymann nephritis in rats. The anti-CD69 autoantibody cross-reacted to LRP2 through the homologous amino acid sequence. To our knowledge, this is the first evidence of the existence of anti-CD69 autoantibodies. This autoantibody may modulate the function of CD69- and LRP2-expressing cells.

Immune complex-induced chronic and intense IL-4 independent IgG1-rheumatoid factor production in NZB mice

Immune complexes from the synovial fluid of rheumatoid arthritis (RA) patients, or artificial rheumatoid factors (RF)-like (antibody--antibody) immune complexes, induce a remarkably intense, sustained and selective immunoglobulin (Ig)G1 response under certain experimental conditions in mice. Because the IgG1 antibody response is extraordinarily strong, the role of interleukin (IL)-4, important for IgG1 synthesis, was investigated. Both C57BL/6 and NZB IL-4-deficient mice produced IgG1--RF antibodies after injection with RF-like immune complexes, although the antibody levels were slightly delayed compared to wild type mice. This shows that IL-4 is not obligatory in RF-like immune complex induced IgG1--RF production. A discrepancy in the decline of serum IgG1--RF was noted between NZB and C57Bl/6 mice. Serum IgG1-RF declined 43 days postinjection (p.i.), in C57BL/6 mice whereas high serum levels of IgG1--RF were maintained more than 100 days in the NZB mice, indicating different regulatory mechanisms in these mice. To study if the affinity for mouse IgG increased with time in NZB mice and thus become more directed against self, the cross-reactivity of the IgG1--RF antibodies with IgG from other species was investigated early and late after injection. It was, however, found that the cross-reactivity with IgG of human, goat and rabbit origin did not change between the two time points.

Immune complexes present in the sera of autoimmune mice activate rheumatoid factor B cells

The fate of an autoreactive B cell is determined in part by the nature of the interaction of the B cell receptor with its autoantigen. In the lpr model of systemic autoimmunity, as well as in certain human diseases, autoreactive B cells expressing rheumatoid factor (RF) binding activity are prominent. A murine B cell transgenic model in which the B cell receptor is a RF that recognizes IgG2a of the j allotype (IgG2aj), but not the b allotype, was used in this study to investigate how the form of the autoantigen influences its ability to activate B cells. We found that sera from autoimmune mice, but not from nonautoimmune mice, were able to induce the proliferation of these RF+ B cells but did not stimulate B cells from RF- littermate controls. The stimulatory factor in serum was found to be IgG2aj, but the IgG2aj was stimulatory only when in the form of immune complexes. Monomeric IgG2aj failed to stimulate. Immune complexes containing lupus-associated nuclear and cytoplasmic autoantigens were particularly potent B cell activators in this system. Appropriate manipulation of such autoantibody/autoantigen complexes may eventually provide a means for therapeutic intervention in patients with certain systemic autoimmune disorders.

Salivary gland lymphomas in patients with Sjögren's syndrome may frequently develop from rheumatoid factor B cells

OBJECTIVE

Patients with Sjögren's syndrome (SS) have an increased risk of developing monoclonal B cell non-Hodgkin's lymphomas (MNHL), which frequently occur in the salivary glands (SG). The transition from the benign lymphocyte infiltrate of the gland that characterizes SS to MNHL is not well understood. Previous sequence analyses of the expressed variable (V) region genes have supported the theory that the surface Ig (sIg) plays an important role in the initial expansion of nonmalignant B cell clones and in lymphomagenesis. However, the antigenic specificities of these B cells were unknown. We describe the specificities of the Ig expressed by 2 cases of MNHL that developed in the SG of 2 patients with SS.

METHODS

The expressed V genes were amplified by polymerase chain reaction from biopsy specimens, sequenced, and subcloned into eukaryotic expression vectors. The constructs were transfected into P3X63-Ag8.653 cells to obtain 2 monoclonal cell lines, each secreting 1 of the sIg expressed by the MNHL. These IgM were tested by enzyme-linked immunosorbent assay and immunofluorescence against a panel of antigens potentially implicated in SS.

RESULTS

Our main finding was that the Ig products of the neoplastic B cells were rheumatoid factors (RF). Contrary to expectations, they did not react with nuclear or cytoplasmic antigens, double-stranded DNA, self antigens commonly bound by natural autoantibodies, or SG tissue.

CONCLUSION

Previous analyses of V gene use have provided indirect evidence that SG MNHL may frequently express RF. We demonstrate that this hypothesis is true in the 2 patients we studied. Large-scale studies will be needed to establish the exact frequency of RF specificity among SS-associated MNHL.

Recombinant cytomegalovirus glycoprotein gB (UL55) induces an autoantibody response to the U1-70 kDa small nuclear ribonucleoprotein

Human cytomegalovirus (CMV) infection can be life threatening in the immune compromised and is associated with congenital defects and / or mental retardation in the neonate. The demonstrated association between CMV infection and rheumatoid factor (RF) raised the possibility of an induction of an autoimmune response upon vaccination with a candidate CMV vaccine, glycoprotein gB (UL55). The antibody responses generated after injections of an adenovirus-gB construct (Ad-gB) were studied in autoimmune-prone (MRL/mpj) and normal (BALB.k, C3H, and BALB/c) mice. Enzyme-linked immunosorbent assay and immunoblot analyses were done to identify the autoantibodies produced following immunization. Immunization with Ad-gB induced a significant IgG anti-viral response in all strains tested (p < 0.0001) compared to phosphate-buffered saline or HeLa controls. Ad-gB induced a significant IgG autoantibody response (p > 0.005) to the U1-70 kDa spliceosome protein in both autoimmune and normal strains whereas immunization with recombinant human La/SS-B did not. Autoantibodies to U1-70 kDa are part of the anti-ribonucleoprotein response seen in systemic lupus erythematosus and mixed connective tissue disease. Low levels of IgG RF and anti-double-stranded DNA antibodies were also induced. This study raises concern that immunization with CMV gB in individuals genetically predisposed to autoimmunity could trigger the development or acceleration of an autoimmune disease.

Human rheumatoid factor production is dependent on CD40 signaling and autoantigen

High-affinity pathologic rheumatoid factor (RF) B cells occur in autoimmune diseases such as rheumatoid arthritis, but are deleted in healthy individuals. The reasons for the survival and differentiation of these autoreactive B cells in rheumatoid arthritis are not known. Previous studies in mice transgenic for a human IgM RF have shown that peripheral encounter with soluble human IgG leads to deletion of high-affinity RF B cells; however, deletion can be prevented when concomitant T cell help is provided. This study aimed to further discern the minimal factors necessary not only for the in vivo survival of RF B cells, but also for their differentiation into Ab-secreting cells. The combination of MHC class II-reactive T cells and Ag induced the production of RF in human IgM RF transgenic mice, while either stimulus alone was ineffective. Neutralizing Abs against CD40 ligand (CD40L), but not against IL-4 or IL-15, abrogated IgM-RF production. Moreover, blockade of CD40L-CD40 allowed IgG to delete the RF precursor cells. Most importantly, activating Abs to CD40 could substitute entirely for T cell help in promoting the survival of RF precursors and in stimulating RF synthesis in T cell deficient animals. The data indicate that CD40 signaling alone can prevent deletion of RF B cells by Ag and in the presence of IgG is sufficient to trigger RF synthesis. The results suggest that selective induction of apoptosis in high-affinity RF B cells may be achieved by blockade of CD40L-CD40 interaction.

HLA-DR/DQ interaction in patients with erosive rheumatoid arthritis presenting articular and extraarticular disease manifestations

In the present study we have analysed the effect of HLA-DRB1 and -DQB1 alleles on disease progression and genetic predisposition among 201 RA patients. We clearly confirm the association of RA with HLA class II alleles sharing the (Q)R/KRAA amino acid (AA) cassette in the third hypervariable region (HVR3) of the DR beta-chain. The HVR3 (Q)R/KRAA motif was significantly overrepresented among RA patients (79% vs. 40%, P < 0.001), with one third of the patients homozygous (28% vs. 6.7%, P < 10(-9)) and the number of rheumatoid factor positive (RF+) patients was significantly increased among HVR3 (Q)R/KRAA homozygous in comparison to HVR3 (Q)R/KRAA negative individuals. Erosive disease defined by the Larsen Score and personal disability determined using the Health Assessment Questionnaire (HAQ) was significantly increased among patients positive for the HVR3 motif with the worst outcome among HVR3 (Q)R/KRAA homozygous patients. In contrast, there was no association of the shared HVR3 AA cassette and disease severity in the majority of patients presenting systemic (extraarticular) disease. Homozygosity for the shared HVR3 motif was only marginally increased among patients presenting 'severe' extraarticular disease in comparison to patients with articular disease (33% vs. 43%, P = ns). Similarly, patients with nodular disease were not more often homozygous for the HVR3 (Q)R/KRAA motif. Furthermore, we observed no HLA-DR independent association of DQB1 alleles among HVR3 (Q)R/KRAA positive patients and controls. Our analysis supports the predominant role of HLA-DR for genetic susceptibility to RA. In the clinical setting, however, HLA-DR typing may be limited to assess the individual risk of patients for disease progression.

The specificity of synovial IgM rheumatoid factors (RF) for genetically engineered IgG antibodies is not affected by the method used to immortalize RF-producing B cells

Previously, we have shown that some rheumatoid factors (RFs) produced by Epstein-Barr virus (EBV)-transformed B cells from patients with rheumatoid arthritis (EBV-RA-RF) appear to be disease-specific autoantibodies that bind differently to defined epitopes on genetically engineered IgG antibodies, compared with RFs expressed by patients with Waldenstrom's macroglobulinaemia (Wmac-RFs) and healthy immunized donors (HID-RFs). To exclude the possibility that EBV transformation is responsible for these differences, we have now studied 15 other monoclonal IgM RFs from patients with RA that were produced by heterohybridoma-B-cell fusion (HRA-RFs). These HRA-RFs show the same gross specificity profiles for IgG as do their EBV-RA-RF counterparts. However, when the specificities of the HRA-RF and EBV-RA-RF panels were combined and compared with those RFs from patients with Wmac or HID, significant differences in binding specificity were again observed. Hybrid IgG3/4 antibodies made by exon shuffles between the IgG3 and IgG4 wild-type genes, and families of IgG variant antibodies made by site-directed mutagenesis, were used to map the fine specificity of HRA-RFs. The fine specificity of HRA-RFs were also similar to those of EBV-RA-RFs. These studies demonstrate that the method used for immortalizing IgM, RF-producing B cells from RA patients does not influence the specificity of the RFs obtained. Furthermore, some RFs expressed in RA have distinct and unique specificities, and may therefore represent disease-specific autoantibodies.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Hepatitis C virus infection, mixed cryoglobulinemia, and non-Hodgkin's lymphoma: an emerging picture

Hepatitis C virus (HCV) is a single-stranded RNA agent which expresses its genetic informations in the form of a single, large polyprotein encoded by an open reading frame (ORF) that extends through most of its genomic RNA. Proteolytic cleavage of the ORF product is essential for the virogenesis and the production of viral progeny. HCV is responsible for chronic liver disease, cirrhosis and possibly hepatocellular carcinoma. Viral persistence is considered the greatest problem in the management of HCV infection. It may result from several mechanisms, two of which are established. In the first, the high rate of genetic variations during viral replication results in the production of mutants capable of escaping the immune attack. In the second, the virus infects cells of the immune system itself, which represent a privileged site that cannot be reached by virus-specific T cell response. Involvement of lymphoid cells in the early stages of HCV infection may provide insight into the pathobiologic patterns of extrahepatic dissemination (lymph nodes, major salivary glands, kidneys, blood vessels). Dissemination of HCV-infected lymphoid cells throughout the organism is likely to maintain a mobile and extensive reservoir of the virus. In this respect, extrahepatic sites may act as a source of continuous reinfection of hepatocytes. Studies of intrahepatic B lymphocytes indicate that they are infected with HCV, clonally expanded and activated to secrete IgM molecules with rheumatoid factor activity. This strongly suggests that HCV directly stimulates B cell expansion, which may result in an indolent stage of lymphoproliferation (i.e., mixed cryoglobulinemia) or in frank B cell non-Hodgkin's lymphoma (NHL). The frequency of NHL, however, is much lower than that of HCV infection, suggesting that HCV alone is not able to induce tumors and that cellular events, in addition to the presence of virus and virus-encoded products, are necessary in order to obtain a malignant B cell phenotype. The demonstration of HCV productive infection in bone marrow-recruited and circulating pluripotent hematopoietic CD34+ stem cells indicates that HCV replication occurs in the early differentiation stages of hematopoietic progenitors. These are stable cell populations and are likely to represent the initial site of infection and a continuous source of virus production.

Does smoking stimulate rheumatoid factor production in non-rheumatic individuals?

Smoking has been associated with increased incidence of rheumatoid arthritis (RA), joint damage and positive rheumatoid factor (RF). Here we report an analysis of the association between smoking and IgM, IgG and IgA RF in a cohort of non-rheumatic individuals participating in a prospective longitudinal study of the incidence and significance of elevated RF. From the initial cohort of nearly 14,000 randomly selected individuals aged 52-80 years, 109 RF-positive and 187 RF-negative non-rheumatic participants were recruited. All participants were tested for RF at least twice at an interval ranging from 4 to 13 years. Of the RF-negative participants 21.9% were active smokers compared to 34.1% of IgM RF-positive (p=0.035), 20.8% of IgG RF-positive (N.S.) and 34.4% of IgA RF-positive participants (p=0.047). Smoking was most prevalent (44.8%) amongst participants with elevation of both IgM and IgA RF (p=0.008), and smokers were also significantly more likely to have a persistent elevation of RF than non-smokers (p=0.024). These findings indicate that smoking may influence the immune system, leading to increased production of IgM and IgA RF.

Induction of IgG rheumatoid factor (RF) production by antibody-antibody (RF-like) immune complexes: the role of T cells, complement and Fc gamma receptors

Rheumatoid factors (RF) are autoantibodies with specificity for the constant regions of IgG molecules. They are found in several immunopathological diseases. The mechanism(s) by which these autoantibodies are produced is largely unknown. We have previously shown that a single injection of RF-like immune complexes (ICs) into mice selectively induced an intense IgG1-antibody production with RF activity. This response was sustained for several months and did not resemble a conventional immune response to an antigen or other immune complexes. In the present study, we sought to elucidate the mechanism for the IgG1 RF response to RF-like ICs. Therefore, the roles of CD4+ T cells, complement and Fc gamma receptors were analysed. In order to characterize the role of CD4+ T cells, RF-like induced IgG1-RF production was analysed in NZB mice treated with a monoclonal antibody (mAb) against the CD4 molecule, which resulted in complete abrogation of IgG1 RF production. To evaluate the importance of Fc gamma Rs, the effect of RF-like ICs was tested in mice deficient for RF gamma RI/III. A significant decrease in the numbers of IgG1 antibody secreting cells, as well as in serum IgG1 RF levels, was found in the deficient mice, as compared with their normal outbred littermates. The role of complement in RF-like ICs mediated IgG1 RF was tested in complement depleted NZB mice, using Cobra venom factor. The IgG1 RF response in complement depleted and intact mice was comparable. Thus, our results demonstrate that RF-like immune complexes selectively induce an Fc gamma R-dependent, complement independent antibody response in mice.

Do chickens immunized with bacterial immunoglobulin G-binding proteins produce rheumatoid factor-like antibodies?

An association between the production of rheumatoid factor (RF)-like antibodies in animals immunized with bacterial immunoglobulin (Ig)G-binding proteins has been noted. Three potential explanations have been proposed: (1) altered host IgG due to binding of the immunogen; (2) B-cell superantigenic properties of the binding proteins; and (3) idiotype-anti-idiotype response leading to an antibody which acts as an antigen mimic. In order to distinguish among these possibilities, it is necessary to carry out studies in animals whose IgG does not react with the IgG-binding protein immunogen. Consequently, we have determined the effects of immunizing chickens with a purified group C streptococcal IgG-binding protein, FcRc, a bacterium expressing this protein, and appropriate control immunogens. The results of these studies provided evidence for production of specific antibodies to FcRc in groups of chickens immunized with either the pure protein or bacteria expressing the protein. No significant association with production of RF-like antibodies was noted, favouring the altered IgG-binding explanation for the association between RF-like antibodies and immunization with the bacterial IgG-binding proteins.

Maternal Ig mediates neonatal tolerance in rheumatoid factor transgenic mice but tolerance breaks down in adult mice

We have recently demonstrated that B cell deletion occurs in the bone marrow of IgHa high affinity anti-IgG2a(a) (RF) transgenic mice. Here we demonstrate via genetic crosses that the source of IgG2a is the mother, thus establishing a transplacental mechanism that ensures tolerance to developmentally expressed Ags. Since maternal IgG can mediate tolerance in young mice, whether tolerance is maintained or, instead, autoimmunity ensues after weaning was investigated. We find that deletion remits abruptly in these RF transgenic mice beginning at 2 to 3 wk postweaning, and some degree of autoreactivity can be observed thereafter for weeks to months. The mechanism of sustained expression of autoreactive RF B cells in normal mice is unclear as yet, but a plausible mechanism is that once self-reactive cells are present, the antibody they secrete markedly reduces the autoantigen levels, presumably allowing further development, rather than deletion, of newly arising B lineage cells. The phenotype of these RF transgenic mice suggests a positive feedback mechanism that tends to perpetuate autoimmunity once it has been established. If such a mechanism were to exist in autoimmune animals, it could have important implications for the establishment and maintenance of B and T cell tolerance in chronic autoimmune diseases.

Mapping IgG epitopes bound by rheumatoid factors from immunized controls identifies disease-specific rheumatoid factors produced by patients with rheumatoid arthritis

We have mapped the specificity of 28 monoclonal IgM rheumatoid factors (RFs) produced by heterohybridomas derived from five healthy blood donors immunized with mismatched human red blood cells (HID). The HID-RFs did not differ in their binding specificity for IgG epitopes from RFs that we previously analyzed from patients with Waldenström's macroglobulinemia. However, IgM RFs produced by HID differed in their specificity for IgG compared with RFs expressed by patients with rheumatoid arthritis (RA-RFs). Only 1 of 28 HID-RFs bound all IgG subclasses (pan binding pattern) compared with 7 of 19 RA-RFs (p = 0.006). Three HID-RFs bound IgG3 compared with 9 RA-RFs (p = 0.007). Fine specificity differences were also identified between HID- and RA-RFs. Therefore, some RA-RFs show novel specificities for IgG not found among RFs from HID or individuals with Waldenström's macroglobulinemia who do not have joint disease. These Abs with unique specificities may represent disease-specific autoantibodies in patients with RA. Nine of the HID-RFs from the same individual were clonally related, and several contained somatic mutations. Even when the clonally related HID-RFs were considered as one RF for comparison, the reactivity of the HID-RFs differed significantly from RA-RFs in their inability to recognize all IgG subclasses (p = 0.044) and recognize IgG3 (p = 0.041). Interestingly, among the clonally related RFs, considerable differences in the specificity for IgG were also observed, with the RF containing the most somatic mutations in VH and VL showing the most distinctive specificity changes. Therefore, these studies also demonstrate a correlation between somatic mutation and binding specificity.

Autoantibodies in mice lacking terminal deoxynucleotidyl transferase: evidence for a role of N region addition in the polyreactivity and in the affinities of anti-DNA antibodies

The generation of terminal deoxynucleotidyl transferase knockout mice (TdT0) has demonstrated that TdT is the only major activity involved in N region addition. This enzyme generates diversity by adding random nucleotides at the V-D-J junctions and by disrupting the formation of repetitive "homology-directed" junctions. Several studies have demonstrated that the Ig heavy chain third complementarity-determining region (H-CDR3) and the N region play a critical role: 1) in distinguishing between polyreactive and monospecific combining sites in natural and Ag-induced Abs; and 2) in the specificity and polyreactivity of natural autoantibodies (autoAbs) and in particular of anti-DNA Abs. To examine the impact of the lack of TdT on the natural autoAb repertoire in adult mice, we have stimulated TdT0 and TdT+ littermates with LPS. Serum studies demonstrate that TdT is not critical for the generation of B cells expressing autoAbs including anti-DNA Abs and rheumatoid factors. However, the generation of a large collection of hybridomas indicates that the frequencies of these cells are reduced in TdT0 mice mainly due to a lower incidence of polyreactivity; also, the lack of N region diversity seems to negatively affect the affinity of anti-DNA Abs. The physiologic relevance of these data is discussed.

HLA-DR/DQ/DP interactions in rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with the presence of particular HLA-DRB1 alleles. In order to characterize HLA-DQB1 and/or-DPB1 alleles that contribute to disease susceptibility besides HLA-DRB1 alleles, we have analysed the HLA-DRB1, -DQB1 and -DPB1 polymorphism in 84 RA patients and 135 controls. HLA typing for HLA-DRB1 and -DQB1 alleles was performed using sequence-specific primers in combination with sequence-based typing. HLA-DPB1 alleles were characterized by reverse dot-blot hybridization. Our data confirm the predominant role of the (Q)R/KRAA sequence from AA position 70-74 of the HLA-DRB chain for disease susceptibility. In particular, the lysine (K) substitution at position 71 was highly significantly associated with RA. Analysis of the DQB1 locus revealed no association with RA when linkage disequilibrium between HLA-DRB1 and -DQB1 alleles was considered. In contrast, we observed an increased frequency of HLA-DPB1*0401 among (Q)R/KRAA-positive patients. (Q)R/KRAA-negative RA patients exhibited an overrepresentation of HLA-DPB1*0201 and HLA-DPB1*0601. Rheumatoid factor (RF) production correlated with the presence of the disease-associated (Q)R/KRAA amino acid cassette of the HLA-DRB chain. When HLA-DPB1 allele frequencies were compared between RF-positive and RF-negative RA patients, we observed an increased frequency of HLA-DPB1*0401 among RF-positive RA patients and HLA-DPB1*0201 among RF-negative patients. These results suggest that besides the predominent role of HLA-DR molecules in RA, HLA-DP molecules may have an influence on disease susceptibility and could modulate disease progression. HLA-DPB1*0401 may function in addition to HLA-DRB1*04, whereas HLA-DPB1*0201 and -DPB1*0601 may represent additional risk factors among (Q)R/KRAA-negative RA patients.

Effect of treatment with methotrexate, hydroxychloroquine, and prednisone on lymphocyte polyamine levels in rheumatoid arthritis: correlation with the clinical response and rheumatoid factor synthesis

OBJECTIVE

Polyamines are increased in activated lymphocytes, including peripheral blood lymphocytes (PBL) from patients with rheumatoid arthritis (RA), and are important in modulating immune-mediated cellular responses. In vitro studies have suggested that methotrexate (MTX) interferes with polyamine synthesis. This study evaluated the in vivo polyamine response to MTX compared to other anti-arthritic agents, and correlated it with the clinical and immunological response.

METHODS

The polyamine content of PBL was determined in 14 RA patients at initiation of treatment with MTX (n = 8), hydroxychloroquine (HCQ) (n = 3), or prednisone (n = 3), and then monthly for four months. IgM rheumatoid factor (RF) synthesis by PBL in vitro was assessed and tender joints were counted monthly.

RESULTS

Polyamines (spermine and spermidine) decreased by 55% at three months in the MTX group compared to 4% and 9% in the HCQ and prednisone groups, respectively (p < 0.01). However, group differences in the clinical and immunological response were not significant. In the MTX group there was a positive correlation between polyamine levels and the joint count. Such a correlation was not observed in the other groups.

CONCLUSION

These data suggest that MTX interference with the polyamine pathway is not shared by prednisone and HCQ, and is associated with its beneficial effect in RA.