Collagen-induced arthritis development requires alpha beta T cells but not gamma delta T cells: studies with T cell-deficient (TCR mutant) mice

Efficient promotion of collagen antibody induced arthritis (CAIA) using four monoclonal antibodies specific for the major epitopes recognized in both collagen induced arthritis and rheumatoid arthritis

An antibody response to defined epitopes located on the triple helical portion of type II collagen (CII) is associated with the development of collagen-induced arthritis (CIA) and rheumatoid arthritis (RA). Monoclonal antibodies to epitopes associated with arthritis, but not antibodies specific for epitopes not associated with arthritis, induce arthritis in mice, the so-called collagen antibody induced arthritis (CAIA) model. We have selected monoclonal IgG antibodies specific for four well-defined major epitopes on triple helical CII, the C1, J1, D3 and U1 epitopes. These antibodies bind the epitopes specifically as determined using recombinant or synthetic triple helical epitopes. They are encoded from somatically mutated V genes. They all bind cartilage in vivo in normal mice. All of the antibodies induce mild arthritis after injection intravenously and if injected as a cocktail they induce severe clinical arthritis. Intravenous injection of a total of 4 mg antibodies (0.5 mg antibodies per clone) induced arthritis in several different mouse strains without any secondary immune stimulus and intraperitoneal injection of LPS 7 days later dramatically raised the severity. Thus, this method is recommended as a new protocol for the induction of CAIA.

Intrinsic Tolerance in Autologous Collagen-Induced Arthritis Is Generated by CD152-Dependent CD4+ Suppressor Cells

Collagen-induced arthritis is a mouse model of rheumatoid arthritis (RA) and is commonly induced after immunization with type II collagen (CII) of a non-mouse origin. T cell recognition of heterologous CII epitopes has been shown to be critical in development of arthritis, as mice with cartilage-restricted transgenic expression of the heterologous T cell epitope (MMC mice) are partially tolerized to CII. However, the mechanism responsible for tolerance and arthritis resistance in these mice is unclear. The present study investigated the regulatory mechanisms in naturally occurring self-tolerance in MMC mice. We found that expression of heterologous rat CII sequence in the cartilage of mice positively selects autoreactive CD4(+) T cells with suppressive capacity. Although CD4(+)CD25(+) cells did not play a prominent role in this suppression, CD152-expressing T cells played a crucial role in this tolerance. MMC CD4(+) T cells were able to suppress proliferation of wild-type cells in vitro where this suppression required cell-to-cell contact. The suppressive capability of MMC cells was also demonstrated in vivo, as transfer of such cells into wild-type arthritis susceptible mice delayed arthritis onset. This study also determined that both tolerance and disease resistance were CD152-dependent as demonstrated by Ab treatment experiments. These findings could have relevance for RA because the transgenic mice used express the same CII epitope in cartilage as humans and because autoreactive T cells, specific for this epitope, are present in transgenic mice as well as in patients with RA.

The plasminogen activator/plasmin system is essential for development of the joint inflammatory phase of collagen type II-induced arthritis

The plasminogen activator (PA) system has been proposed to have important roles in rheumatoid arthritis. Here we have used the autoimmune collagen type II (CII)-induced arthritis (CIA) model and mice deficient for urokinase-type PA (uPA) or plasminogen to investigate the role of the PA system for development of arthritis. Our data revealed that uPA-deficient mice have a lower severity and incidence of CIA than wild-type mice. Furthermore, although >80% of wild-type control mice developed CIA, we found that none of the 50 plasminogen-deficient littermates that were tested developed CIA within a 40-day period. Antibody generation after CII immunization as well as the binding of labeled anti-CII antibodies to the surface of cartilage were similar in wild-type and plasminogen-deficient mice. No sign of inflammation was seen when plasminogen-deficient mice were injected with a mixture of monoclonal antibodies against CII. However, after daily injections of human plasminogen, these mice developed arthritis within 5 days. Our finding that infiltration of inflammatory cells into the synovial joints was impaired in plasminogen-deficient mice suggests that uPA and plasminogen are important mediators of joint inflammation. Active plasmin is therefore essential for the induction of pathological inflammatory joint destruction in CIA.

Contrasting roles of plasminogen deficiency in different rheumatoid arthritis models

OBJECTIVE

To investigate the contrasting roles of plasminogen deficiency between models of collagen-induced arthritis (CIA) and antigen-induced arthritis (AIA).

METHODS

We developed a new animal model of arthritis, which we have called local injection-induced arthritis (LIA). In this model, we replaced methylated bovine serum albumin, which is normally used as an immunogen and is injected intraarticularly into the knee joint, with type II collagen (CII) to induce AIA. The severity of CIA, LIA, and AIA in wild-type and plasminogen-deficient mice was evaluated by clinical scoring or histologic grading. Necrosis was determined by histology and immunohistochemistry.

RESULTS

After CII immunization alone, wild-type mice developed arthritis in most of the paws as well as in the knee joints, whereas plasminogen-deficient mice were totally resistant to the disease. Local knee injections of CII or saline slightly enhanced the severity of the knee arthritis in wild-type mice during a 60-day experimental period. Unexpectedly, the plasminogen-deficient mice also developed arthritis in joints that were injected with CII or saline. However, the arthritis was milder than that in their wild-type littermates. Sustained tissue necrosis was found only in the plasminogen-deficient mice after the local injection.

CONCLUSION

Our data show that both the antigen and the joint trauma caused by the local injection are critical to explaining the contrasting roles of plasminogen deficiency in CIA and AIA. This further indicates that CIA and AIA have distinct pathogenic mechanisms. The data also suggest that plasmin may be required for the induction of these arthritis models that are critically dependent on complement activation.

Regulation of arthritis by p53: Critical role of adaptive immunity

OBJECTIVE

The p53 tumor-suppressor protein is expressed in rheumatoid arthritis synovium, and loss of p53 function through somatic mutation can occur in longstanding disease. Previous studies demonstrated that p53 is protective in murine collagen-induced arthritis (CIA). To determine if adaptive immune responses or synovial effector functions are responsible for this effect, passive models of arthritis were studied in p53 wild-type and knockout mice.

METHODS

Models of passive CIA, passive K/BxN serum transfer arthritis, and active CIA were induced in DBA/1 p53(-/-) or p53(+) mice. Hind paws were evaluated for histologic evidence of inflammation and joint destruction. Synovial interleukin-6 and matrix metalloproteinases 3 and 13 gene expression was analyzed by real-time quantitative polymerase chain reaction. To evaluate T cell function in p53(-/-) mice, draining lymph node (LN) cells from mice immunized with type II collagen (CII) were evaluated in vitro.

RESULTS

Increased disease severity in p53(-/-) mice was confirmed in the standard CIA model. However, clinical arthritis, joint destruction, and synovial gene expression in the passive CIA and K/BxN serum transfer arthritis models were similar in p53(-/-) and p53(+) mice. To determine if the p53 effect was related to T cell function, LN cells from CII-immunized mice were isolated and stimulated with antigen in vitro. CII-stimulated T cell proliferation and interferon-gamma production were significantly higher in p53(-/-) mice. An independent assessment of Th1 function using the cutaneous delayed-type hypersensitivity model confirmed that p53(-/-) mice have enhanced T cell responses in vivo.

CONCLUSION

Adaptive immune responses, rather than antibody-mediated responses, in p53(-/-) mice account for increased disease severity in the active CIA model.

Genetic Interactions in Eae2 Control Collagen-Induced Arthritis and the CD4+/CD8+ T Cell Ratio

The Eae2 locus on mouse chromosome 15 controls the development of experimental autoimmune encephalomyelitis (EAE); however, in this study we show that it also controls collagen-induced arthritis (CIA). To find the smallest disease-controlling locus/loci within Eae2, we have studied development of CIA in 676 mice from a partially advanced intercross. Eae2 congenic mice were bred with mice congenic for the Eae3/Cia5 locus on chromosome 3, previously shown to interact with Eae2. To create a large number of genetic recombinations within the congenic fragments, the offspring were intercrossed, and the eight subsequent generations were analyzed for CIA. We found that Eae2 consists of four Cia subloci (Cia26, Cia30, Cia31, and Cia32), of which two interacted with each other, conferring severe CIA. Genes within the other two loci independently interacted with genes in Eae3/Cia5. Investigation of the CD4/CD8 T cell ratio in mice from the partially advanced intercross shows that this trait is linked to one of the Eae2 subloci through interactions with Eae3/Cia5. Furthermore, the expression of CD86 on stimulated macrophages is linked to Eae2.

Collagen type II (CII)-specific antibodies induce arthritis in the absence of T or B cells but the arthritis progression is enhanced by CII-reactive T cells

Antibodies against type II collagen (anti-CII) are arthritogenic and have a crucial role in the initiation of collagen-induced arthritis. Here, we have determined the dependence of T and B cells in collagen-antibody-induced arthritis (CAIA) during different phases of arthritis. Mice deficient for B and/or T cells were susceptible to the CAIA, showing that the antibodies induce arthritis even in the absence of an adaptive immune system. To determine whether CII-reactive T cells could have a role in enhancing arthritis development at the effector level of arthritis pathogenesis, we established a T cell line reactive with CII. This T cell line was oligoclonal and responded to different post-translational forms of the major CII epitope at position 260-270 bound to the Aq class II molecule. Importantly, it cross-reacted with the mouse peptide although it is bound with lower affinity to the Aq molecule than the corresponding rat peptide. The T cell line could not induce clinical arthritis per se in Aq-expressing mice even if these mice expressed the major heterologous CII epitope in cartilage, as in the transgenic MMC (mutated mouse collagen) mouse. However, a combined treatment with anti-CII monoclonal antibodies and CII-reactive T cells enhanced the progression of severe arthritis.

Collagen type II-specific monoclonal antibody-induced arthritis in mice: description of the disease and the influence of age, sex, and genes

Transfer of collagen type II (CII)-specific monoclonal antibodies induces an acute form of arthritis (collagen type II antibody-induced arthritis, CAIA) in naïve mice. Arthritis was induced using a pair of monoclonal antibodies M2139 and CIIC1, binding to J1 and C1(I) epitopes of CII, respectively. Thereafter, lipopolysaccharide injection was used to increase the incidence and severity of the disease. This model was used to investigate the effect of genes, age, and sex as well as effector cells in the end-stage effector phase of arthritis pathogenesis. Injection of a single monoclonal antibody induced arthritis only after lipopolysaccharide stimulation. CAIA showed differences in disease penetration among the susceptible strains indicating the importance of non-major histocompatibility complex genes on the antibody effector pathway. B-cell-deficient mice were susceptible to CAIA and in some genetic backgrounds B-cell deficiency leads to enhanced arthritis. Histology of the affected paws revealed massive infiltrations of neutrophils along with bone and cartilage erosion, pannus formation, and fibrin deposition. Depletion of neutrophils significantly reduced the incidence and severity of the disease. CAIA susceptibility increased with age. Males were more susceptible than females and estrogen treatment decreased the development of arthritis. We conclude that CAIA is an acute arthritis triggered by antibody binding and neutrophils bypassing immune activation but with many characteristics in common with collagen-induced arthritis.

Glycosylation of type II collagen is of major importance for T cell tolerance and pathology in collagen-induced arthritis

Type II collagen (CII) is a candidate cartilage-specific autoantigen, which can become post-translationally modified by hydroxylation and glycosylation. T cell recognition of CII is essential for the development of murine collagen-induced arthritis (CIA) and also occurs in rheumatoid arthritis (RA). The common denominator of murine CIA and human RA is the presentation of an immunodominant CII-derived glycosylated peptide on murine Aq and human DR4 molecules, respectively. To investigate the importance of T cell recognition of glycosylated CII in CIA development after immunization with heterologous CII, we treated neonatal mice with different heterologous CII-peptides (non-modified, hydroxylated and galactosylated). Treatment with the galactosylated peptide (galactose at position 264) was superior in protecting mice from CIA. Protection was accompanied by a reduced antibody response to CII and by an impaired T cell response to the glycopeptide. To investigate the importance of glycopeptide recognition in an autologous CIA model, we treated MMC-transgenic mice, which express the heterologous CII epitope with a glutamic acid in position 266 in cartilage, with CII-peptides. Again, a strong vaccination potential of the glycopeptide was seen. Hence CII-glycopeptides may be the optimal choice of vaccination target in RA, since humans share the same epitope as the MMC mouse.

The importance of IL-1 beta and TNF-alpha, and the noninvolvement of IL-6, in the development of monoclonal antibody-induced arthritis

Injection of anti-type II collagen Ab and LPS induces arthritis in mice. The levels of IL-1 beta, IL-6, and chemokines (macrophage inflammatory protein (MIP)-1 alpha, MIP-2, and monocyte chemoattractant protein-1) in the hind paws increased with the onset of arthritis and correlated highly with arthritis scores. The level of TNF-alpha was also elevated, but only transiently. Quantitative real-time PCR analysis revealed increases in cytokine and chemokine mRNA. To elucidate the contribution of inflammatory cytokines and chemokines in arthritis development more directly, recombinant proteins, neutralizing Abs, and knockout mice were used. The injection of rIL-1 beta or TNF-alpha, but not IL-6 or chemokines, induced arthritis when mice were i.v. preinjected with anti-type II collagen Ab. However, a single injection of recombinant cytokines or chemokines into the hind paws did not induce swelling. Arthritis development was inhibited by neutralizing Ab against IL-1 beta, TNF-alpha, or MIP-1 alpha. In contrast, the inhibitory effect by anti-MIP-2 Ab was partial and, surprisingly, Abs to IL-6 and monocyte chemoattractant protein-1 showed no inhibitory effect. Furthermore, arthritis development in IL-1R(-/-) mice and TNFR(-/-) mice was not observed at all, but severe arthritis was developed in IL-6(-/-) mice. These results suggest that IL-1 beta and TNF-alpha play more crucial roles than IL-6 or chemokines in this model. Because arthritis was also developed in SCID mice, the development of arthritis in the Ab-induced mice model is due to a mechanism that does not involve T or B cells.

Syngeneic fibroblasts transfected with a plasmid encoding interleukin-4 as non-viral vectors for anti-inflammatory gene therapy in collagen-induced arthritis

BACKGROUND

No effective long-term treatment is available for rheumatoid arthritis. Recent advances in gene therapy and cell therapy have demonstrated efficiency in collagen-induced arthritis (CIA). Interleukin-4 (IL-4) is already known to be efficient in CIA in systemic injection or administered by gene therapy. This study was designed to evaluate the effect of a non-viral gene therapy of CIA, involving injection of syngeneic fibroblasts transfected with a plasmid encoding for IL-4.

METHODS

Immortalised fibroblasts from DBA/1 mice (DBA/1/0 cells) were transfected with a plasmid expressing IL-4 cDNA (DBA/1/IL-4 cells). Xenogeneic fibroblasts from Chinese hamster ovary (CHO) transfected with a plasmid expressing IL-4 cDNA (CHO/IL-4) were studied also. The cells were engrafted in mice developing CIA by subcutaneous injection of 3 x 10(6) DBA/1/0 or DBA/1/IL-4 or CHO/IL-4 cells.

RESULTS

Injection of DBA/1/IL-4 cells, on days 10 and 25 after immunisation, was associated with a significant and lasting improvement in the clinical and histological evidence of joint inflammation and destruction as compared with DBA/1/0 and CHO/IL-4 cells. DBA/1/IL-4 cell treatment decreased also the production of IgG2a antibody to CII and the proliferation of CIIB-specific nodal T cells. Later treatments (engraftments on days 23 and 35 after immunisation) exerted also an anti-inflammatory effect, as evaluated on clinical and histological signs of CIA.

CONCLUSIONS

Taken together, these findings indicate that systemic administration of syngeneic cells transfected with an anti-inflammatory cytokine gene, namely IL-4, with a non-viral method is effective in CIA and may attenuate the cytokine imbalance seen in this disease.

Gammadelta T cells: functional plasticity and heterogeneity

Gammadelta T cells remain an enigma. They are capable of generating more unique antigen receptors than alphabeta T cells and B cells combined, yet their repertoire of antigen receptors is dominated by specific subsets that recognize a limited number of antigens. A variety of sometimes conflicting effector functions have been ascribed to them, yet their biological function(s) remains unclear. On the basis of studies of gammadelta T cells in infectious and autoimmune diseases, we argue that gammadelta T cells perform different functions according to their tissue distribution, antigen-receptor structure and local microenvironment; we also discuss how and at what stage of the immune response they become activated.

Primed B cells present type-II collagen to T cells

Development of type-II collagen (CII)-induced arthritis (CIA) is dependent on a T-cell mediated activation of autoreactive B cells. However, it is still unclear if B cells can present CII to T cells. To investigate the role of B cells as antigen-presenting cells (APCs) for CII, we purified B cells from lymph nodes of immunized and nonimmunized mice. These B cells were used as APC for antigen-specific T-cell hybridomas. B cells from naïve mice did present native, triple-helical, CII (nCII) but also ovalbumin (OVA) and denatured CII (dCII) to antigen-specific T-cell hybridomas. In addition, B cells primed with nCII or OVA, but not dCII, activated the antigen-specific T-cell hybridomas two to three times better than naïve B cells. We conclude that antigen-primed B cells have the capacity to process and present CII to primed T cells, and antigen-primed antigen-specific B cells are more efficient as APC than naïve B cells. We further conclude that B cells have the potential to play an important role as APC in the development of CIA.

Differing roles for urokinase and tissue-type plasminogen activator in collagen-induced arthritis

The plasminogen activators, urokinase PA (u-PA) and tissue-type PA (t-PA), are believed to play important roles in inflammatory cell infiltration, fibrin deposition, and joint destruction associated with rheumatoid arthritis; however, their precise roles in such processes, particularly u-PA, have yet to be defined. Using gene-deficient mice we examined the relative contribution of the PAs to the chronic systemic collagen-induced arthritis model. Based on clinical and histological assessments, u-PA-/- mice developed significantly milder disease and t-PA-/- mice more severe disease compared with the relevant wild-type mice. Fibrin deposition within joints paralleled disease severity and was particularly pronounced in t-PA-/- mice. Likewise, cytokine levels in the synovium reflected the severity of disease, with interleukin-1beta levels in particular being lower in u-PA-/- mice and increased in t-PA-/- mice. The antibody response to type II collagen was normal in both knockouts; however, T cells from u-PA-/- mice had a reduced proliferative response and produced less interferon-gamma on antigen stimulation in vitro. These results indicate that the major effect of u-PA in the collagen-induced arthritis model is deleterious, whereas that of t-PA is protective. Our data highlight the complexities of PA function, and suggest that approaches either to target u-PA or to enhance local t-PA activity in joints may be of therapeutic benefit in rheumatoid arthritis.

Role of glycopeptide-specific T cells in collagen-induced arthritis: an example how post-translational modification of proteins may be involved in autoimmune disease

Immunization of mice with type II collagen (CII), a cartilage-restricted protein, leads to collagen-induced arthritis (CIA), a model for rheumatoid arthritis (RA). CIA symptoms consist of an erosive joint inflammation caused by an autoimmune attack, mediated by both T and B lymphocytes. CD4+ alphabeta T cells play a central role in CIA, both by helping B cells to produce anti-CII antibodies, and by interacting with other cells in the joints, eg macrophages. In H-2q mice, most CII-specific CD4+ T cells recognize the CII(256-270) peptide presented on the major histocompatibility complex (MHC) class II Aq molecule. Post-translational modifications (hydroxylation and variable glycosylation) of the lysine residue at position 264 of CII generate at least four different T-cell determinants that are specifically recognized by distinct T-cell subsets. Most T cells recognize CII(256-270) glycosylated with the monosaccharide galactose, which is consequently immunodominant in CIA. Recent studies indicate that the arthritogenic T cells in CIA are glycopeptide-specific, suggesting that induction of self-tolerance may be rendered more difficult by glycosylation of CII. These data open the possibility that outoimmune disease may be caused by the creation of new epitopes by posttranslational modification of proteins under circumstances such as trauma, inflammation or ageing.

Enhancement of collagen-induced arthritis in female mice by estrogen receptor blockage

OBJECTIVE

To determine whether estrogen-mediated suppression of collagen-induced arthritis (CIA) in mice acts via the nuclear estrogen receptors (ERs).

METHODS

CIA was induced in noncastrated normal (B10.Q x DBA/1)F1 (QD) female mice. The mice were treated with the ER antagonist ICI 182,780, which binds to both ERalpha and ERbeta, either on days 2, 6, 10, and 14 or on days 14, 18, 22, and 26 after type II collagen (CII) immunization. The effects of treatment and development of arthritis were correlated with the estrus cycle by inspection of vaginal smears (VS). By a combination of treatments with both estriol (E3) and ICI 182,780 during the time of expected onset of CIA in castrated QD female mice, the protective effect of E3 in CIA was analyzed.

RESULTS

Treatment with ICI 182,780 of QD female mice immunized with CII triggered an earlier onset of arthritis during the period when the estrus cycle was blocked. The arthritis-modulating effect of ICI 182,780 was even obtained at doses that were insufficient to block estrus cycling, as observed in the VS response. E3 is an estrogen with low estrogenic potency but with a relatively potent antiarthritis effect. Doses of ICI 182,780 that were suboptimal for blocking estrus cycling blocked the E3-mediated suppression of CIA in castrated female mice.

CONCLUSION

These findings show that estrogen-induced suppression of CIA is mediated via the nuclear ERs and is operating at physiologic, possibly even subphysiologic, levels of estrogens.

Interference with CD28, CD80, CD86 or CD152 in collagen-induced arthritis. Limited role of IFN-gamma in anti-B7-mediated suppression of disease

We have investigated interference with co-stimulation by administering mAbs towards CD28, CD80, CD86, and CD152 in mice immunized for the development of collagen-induced arthritis (CIA). Anti-CD80 and anti-CD86 treatment inhibited disease score and incidence, whereas anti-CD28 treatment led only to a delayed disease onset. Administration of anti-CD152 had no effect. The CII-specific Ab-response was suppressed by the co-stimulatory blockade, with a stronger effect on IgG1 than on IgG2a. The CII-driven T cell proliferation, on the other hand, was not affected. Furthermore, T cells primed in the presence of either anti-B7 or anti-CD28 produced markedly increased amounts of IFN-gamma in response to CII. To investigate whether this increase in IFN-gamma was related to disease suppression, IFN-gamma-deficient mice were immunized with CII, treated with anti-B7 and followed for the development of arthritis. As in the wild-type mice, administration of anti-B7 to IFN-gamma-deficient mice led to a reduced disease incidence and severity as well as reduced anti-CII IgG titers. Collectively, these data stress the importance of co-stimulation for the delivery of B cell help rather than for production of Th1 cytokines. We also demonstrate that the enhanced production of IFN-gamma observed after B7-blockade is not accountable for the anti-B7 mediated inhibition of CIA.

Influence of CD4 or CD8 deficiency on collagen-induced arthritis

The role of T cells in the mouse collagen-induced arthritis (CIA) model for rheumatoid arthritis is not clarified, and different results have been reported concerning the role of CD4 and CD8 T cells. To address this issue, we have investigated B10.Q mice deficient for CD4 or CD8. The mice lacking CD4 were found to be less susceptible to disease, but not completely resistant, whereas the CD8 deficiency had no significant impact on the disease. No difference in the development of late occurring relapses was noted. Interestingly, the CD4-deficient mice had a severely reduced response to the glycosylated form of the immunodominant type II collagen (CII) 256-270 peptide whereas the response to the non-glycosylated peptide was not significantly different. Furthermore, CD4-deficient mice had lower antibody responses to CII, explaining the lower disease susceptibility. In comparison with previously reported results, it is apparent that the lack of CD4 molecules has a different impact on CIA if present on different genetic backgrounds, findings that could possibly be related to the occurrence of different disease pathways of CIA in different mouse strains.

Evaluation of the percentage of peripheral T cells with two different T cell receptor alpha-chains and of their potential role in autoimmunity

Approximately 25% of mature T cells possess two distinct cytoplasmic T cell receptor (TCR) alpha-chains, due to productive gene rearrangements of both alleles. Expression of two different alpha-chains at the cell surface is a potential risk factor for development of autoimmunity. However, it has been difficult to determine the frequency of peripheral T cells with two different alpha-chains at the surface. Our new approach is based on comparing by flow cytometry the percentage of cells that express a given Valpha-chain between wild-type mice and mice that are hemizygous for a disrupted Tcra locus (Tcra+/-) and consequently unable to express two rearranged Tcra genes. We consistently found that approximately 8% of total peripheral T cells express two surface alpha-chains. The importance of dual alpha-T cells in autoimmunity was examined in a mouse model for rheumatoid arthritis, namely collagen-induced arthritis (CIA). No significant difference was observed between Tcra+/- mice and wild-type littermates, considering arthritis incidence, day of disease onset, and maximum arthritic score. We therefore conclude that there is incomplete phenotypic allelic exclusion in TCRalpha, and that the presence of a significant number of potentially multireactive T cells does not increase the susceptibility to develop autoimmune arthritis.

Genetic control of collagen-induced arthritis in a cross with NOD and C57BL/10 mice is dependent on gene regions encoding complement factor 5 and FcgammaRIIb and is not associated with loci controlling diabetes

The nonobese diabetic (NOD) mouse spontaneously develops autoimmune-mediated diseases such as diabetes and Sjögren's syndrome. To investigate whether NOD genes also promote autoimmune-mediated arthritis we established a NOD strain with an MHC class II fragment containing the A(q) class II gene predisposing for collagen induced arthritis (NOD.Q). However, this mouse was resistant to arthritis in contrast to other A(q) expressing strains such as B10.Q and DBA/1. To determine the major resistance factor/s, a genetic analysis was performed. (NOD.Q x B10.Q)F1 mice were resistant, whereas 27% of the (NOD.Q x B10.Q)F2 mice developed severe arthritis. Genetic mapping of 353 F2 mice revealed two loci associated with arthritis. One locus was found on chromosome 2 (LOD score 9.8), at the location of the complement factor 5 (C5) gene. The susceptibility allele was from B10.Q, which contains a productive C5 encoding gene in contrast to NOD.Q. The other significant locus was found on chromosome 1 (LOD score 5.6) close to the Fc-gamma receptor IIb gene, where NOD carried the susceptible allele. An interaction between the two loci was observed, indicating that they operate on the same or on interacting pathways. The genetic control of arthritis is unique in comparison to diabetes, since none of these loci have been identified in analysis of diabetes susceptibility.