Characterization of haemorrhagic pulmonary capillaritis: another manifestation of Pristane-induced lupus.

OBJECTIVES: Pristane-induced lupus is a well-established model of murine lupus. Mice injected with Pristane develop lupus-specific autoantibodies and glomerulonephritis. A chance observation led us to identify and characterize haemorrhagic pulmonary capillaritis in Pristane-injected mice. METHODS: Eight-week-old C57Bl/10 (B10, H-2(b)) mice received a single intraperitoneal injection of 0.5 ml of Pristane. Control mice received phosphate-buffered saline (PBS) injection. Mice were bled at 2 weeks after Pristane injection and monthly thereafter for serology and for antinuclear antibody (ANA). To characterize pulmonary disease, bronchoalveolar lavage (BAL) was carried out for total and differential cell count. Cytokines levels were checked for IL-2, IL-4, TNF-alpha, IFN-gamma, IL-6 and IL-10. Lungs were examined by histopathology and electron microscopy. RESULTS: All mice injected with Pristane developed a pulmonary capillaritis with perivascular infiltration with macrophages, neutrophils, lymphocytes and eosinophils. In addition, alveoli showed macrophage and neutrophil infiltration. The degree of perivascular and alveolar inflammation was moderate to severe. BAL was inflammatory with cell composition of macrophages, neutrophils, lymphocyte and eosinophils. There was evidence of endothelial injury on electron microscopy but no evidence of immune complex deposition. IL-6 and IL-10 were increased in BAL but levels of TNF-alpha, IFN-gamma, IL-2 and IL-4 were not. Anti-neutrophil cytoplasm antibody (ANCA) was negative. Kidneys demonstrated an increase in mesangial matrix and cellularity compatible with WHO Class II lupus lesion. There were immune complexes and complement deposition in the kidney. There were oil granulomas in peritoneum, spleen and liver but no evidence of vasculitis in these organs was seen. CONCLUSION: The relative ease and high penetrability of lesion makes it an attractive model to study pulmonary vasculitis.

HLA-DR modulates autoantibody repertoire, but not mortality, in a humanized mouse model of systemic lupus erythematosus.

To evaluate the disease-modulating role of HLA-DR2 and DR3 molecules, which have been associated with systemic lupus erythematosus, a humanized mouse model was examined. HLA-DR2 (DRB1*1502)- and DR3 (DRB1*0301)-transgenic mice were backcrossed to the New Zealand Mixed 2410 (NZM 2410, H2(z)) strain. Seventh generation DR2 and DR3 transgene-positive animals along with their transgene-negative littermates and the parental strain NZM2410 were monitored for proteinuria, azotemia, autoantibody production, development of nephritis, and mortality. The results showed no significant differences in proteinuria, azotemia, or mortality between the backcrosses with and without HLA-DR2 or HLA-DR3. However, the genetic analysis of different backcrosses showed that heterozygosity at the endogenous H2-E locus (E(z)/E(b)) was strongly linked with acceleration of lupus nephritis in both HLA-DR2 and HLA-DR3 transgenics. More importantly, the presence of the HLA-DR2, but not the HLA-DR3, transgene significantly enhanced the production of anti-dsDNA, but not anti-ssDNA, anti-histone-dsDNA complex, or anti-histone, Abs. In contrast, neither HLA-DR2 nor HLA-DR3 influenced the development of glomerulonephritis or the degree of immune complex deposition. Moreover, nephritic kidneys from mice with and without HLA-DR2 or HLA-DR3 transgenes showed similar patterns of cytokine expression. Collectively, these findings provide molecular evidence that the association of HLA-DR2 or HLA-DR3 with lupus susceptibility is related to the type of autoantibody rather than to disease mortality. The use of a humanized mouse model provides a way of dissecting the roles of human MHC genes in systemic lupus erythematosus pathogenesis.

Is rheumatoid arthritis care more costly when provided by rheumatologists compared with generalists?

OBJECTIVE: Controversy surrounds the cost-effectiveness of rheumatologist care compared with generalist care for patients with rheumatoid arthritis (RA). Rheumatologists can provide 2 distinct types of care for RA patients: primary care and specialist care. We sought to examine the relationship between cost and type of care in a population-based cohort of patients with RA. METHODS: Data regarding specialty of care and use of health services (i.e., total direct medical costs, surgeries, radiographs, laboratory tests, hospital days) were collected from a community sample of 249 patients with RA (defined using the 1987 American College of Rheumatology diagnostic criteria) among Rochester, Minnesota residents > or =35 years of age. In a randomly selected subset of 99 of these RA patients, detailed information on all physician encounters was collected and categorized according to whether or not the care received constituted "primary care" according to the Institute of Medicine definition. Using these data, we evaluated the influence of type of care as well as specialty of provider on utilization. For these analyses, total direct costs included all inpatient and outpatient health care costs incurred by all local providers (excluding outpatient prescription drugs). RESULTS: The 249 patients with RA (mean age 64 years, 75% women) were followed up for a median of 5.4 years, while the subset of 99 RA patients (mean age 64 years, 77% women) were followed up for a median of 4.7 years. The overall median direct medical costs per person per year were $2,749 and $2,929 for the total cohort and for the subset of 99 patients, respectively. Generalized linear regression analyses (considering all visits of the 249 RA patients) revealed that after adjusting for demographics and disease characteristics, rheumatologist care (compared with nonrheumatologist care) was not associated with higher total direct medical costs (P = 0.85) or more hospital days (P = 0.35), but was associated with slightly more radiographs (P = 0.037) and significantly more laboratory tests (P < 0.0001). When considering only primary care, such care by rheumatologists was, again, not associated with higher total direct medical costs (P = 0.11) or more hospital days (P = 0.69) or more laboratory tests (P = 0.54), but was associated with slightly more radiographs (P = 0.035). CONCLUSION: Rheumatologist care is not more costly than generalist care for patients with RA. Important differences (especially in the use of laboratory tests) become apparent when the type of care provided as well as the specialty of the provider are considered in the analyses.

Spontaneous inflammatory disease in HLA-B27 transgenic mice does not require transporter of antigenic peptides.

HLA-B27 is strongly linked with a group of human diseases called spondyloarthropathies. Even though HLA-B27 as an MHC class I molecule would be expected to present endogenously processed peptides such as cytosolic or viral proteins, many of the B27-linked diseases begin after an infection with an enterobacteria, an exogenous antigen. In our previous studies, we have described development of spontaneous inflammatory disease in HLA-B27 transgenic mice expressing beta(2)m free heavy chains on the cell surface. In order to address the role of endogenous versus exogenous antigens and a role for Tap genes in the development of spontaneous diseases, mice lacking Tap-1 (knockout) were mated to HLA-B27/human beta(2)m transgenic mice. B27(+)/human beta(2)m(+) double-transgenic mice (without mouse beta(2)m) lacking the Tap-1 gene developed spontaneous inflammatory disease similar to wild-type Tap-1 gene-expressing counterparts. Our data demonstrate that peptide transporters (Tap) were not involved in the development of spontaneous inflammatory disease in B27(+)/human beta(2)m transgenic animals.

HLA-B27 transgenic mice are susceptible to collagen-induced arthritis: type II collagen as a potential target in human disease.

HLA-B27 is highly linked with a group of human diseases called spondyloarthropathies (SpA). Many of these disorders begin after an infection with an enterobacteria. The symptoms seen in patients with spondyloarthropathies are inflammatory pain in the spine and asymmetrical arthritis of lower limbs. Additional symptoms related to SpA include inflammation in the eyes, bowel, and skin. The autoantigen(s) in SpA are not known. Proteins such as collagen and proteoglycans have been thought to be potent autoantigens in arthritidis including B27-associated human diseases. Type II collagen is a common denominator among eyes and joints, affected tissues in B27-linked diseases. Moreover, a few reports indicated CII specific T cells and antibodies in patients with spondyloarthropathies. We and others have previously described development of spontaneous arthritis and nail disease in HLA-B27 transgenic animals. To determine whether CII may be a target antigen in the B27-linked diseases, B27 + m beta 2 m% (HLA-B27) transgenic mice lacking mouse beta 2m with and without human beta 2m) mice were immunized with type II collagen inside the barrier facility. Male HLA-B27 transgenic mice developed collagen-induced arthritis compared to transgene negative littermates or female counterparts. There was no difference in the incidence of arthritis in HLA-B27 transgenic mice with and without human beta 2m. Our data suggest that beta 2m free heavy chain of HLA-B27 may present soluble antigens such as type II collagen to trigger specific T cells contributing in the development of arthritis. Our data also suggest that CII may be a potential target antigen in the cartilage during the disease process.

Lymphomas in patients with connective tissue disease. Comparison of p53 protein expression and latent EBV infection in patients immunosuppressed and not immunosuppressed with methotrexate.

Cell cycle dysregulation as measured by p53 protein expression and latent Epstein-Barr (EBV) infection are important in the pathogenesis of lymphoma, particularly in immunosuppressed patients. Although latent EBV commonly is detected in lymphomas arising in patients with connective tissue disease who are immunosuppressed with methotrexate, p53 protein expression has not been reported. We compared the immunohistologic expression of p53 protein and the incidence of latent EBV infection in lymphomas arising in patients with connective tissue disease treated and not treated with methotrexate. Increased p53 staining was detected in 10 of 11 lymphomas arising in patients after methotrexate therapy vs 5 of 11 in patients not treated with methotrexate. Latent EBV was detected in 7 of 13 lymphomas arising in patients after methotrexate therapy vs 2 of 11 in patients not treated with methotrexate. Concordant p53 expression and latent EBV were detected in 5 of 7 lymphomas arising after treatment with methotrexate, including 1 that regressed after methotrexate therapy was withdrawn. These findings suggest that cell cycle dysregulation and EBV-related transformation are important in the pathogenesis of lymphomas arising in patients with connective tissue disease who are immunosuppressed with methotrexate.

Complementation between HLA-DR4 (DRB1*0401) and specific H2-A molecule in transgenic mice leads to collagen-induced arthritis.

We generated transgenic mice with DRB1*0401 gene with mutation in the beta2 domain (aa 110 and 139) for better interaction with mCD4. The DR4 transgene was introduced into H2-Aq (B10RQB3) and H2-Af (B10RFB3) to examine the role of DR4 in collagen arthritis. The HLA-DR molecules in these mice were found to be functional on the basis of their positive/negative selection of the Vbeta T cell repertoire. H2-Aq mice are resistant to porcine CII-induced arthritis. The RQB3/DR4 mice (H2Aq/DR4) developed severe collagen induced arthritis (CIA) when immunized with Porcine type II collagen while the negative littermates were resistant. RQB3.DR4 mice were also highly susceptible to CIA induced by Human CII while negative littermates got only mild disease. However, RFB3/DR4 mice (H2Af/ DR4) did not get CIA with any type II collagen. Therefore, the DR4 gene in the context of H2-Aq predisposes to severe arthritis but not in the context of H2-Af. Antibodies to renatured cyanogen bromide (CB) cleaved fragments of PII in RQB3/DR4 mice and negative littermates suggest that the presence of DR4 does not result in any differences in specificity of antibody response to CB fragments. These results indicate that a specific gene complementation occurring between DR4 and H2.Aq but not DR4 and H2Af promotes the induction of arthritis with PII and HII in these mice. A similar interaction may be involved between DR and DQ molecules in human RA.

Identification of T cell determinants on human type II collagen recognized by HLA-DQ8 and HLA-DQ6 transgenic mice.

HLA-DQA1*0301 and HLA-DQB1*0302 genes encoding the HLA-DQ8 molecule and HLA-DQA1*0103 and HLA-DQB1*0601 genes encoding the HLA-DQ6 molecule were introduced into H-2Abetao knockout mice. Three lines of transgenic mice were established: HLA-DQ8, HLA-DQ6, and HLA-DQ8beta6alpha. HLA-DQ8 mice are susceptible to collagen-induced arthritis, while HLA-DQ6 mice are resistant. HLA-DQ8beta6alpha mice develop polychrondritis in addition to arthritis. Transgenic mice were primed and challenged with individual synthetic peptides representing human type II collagen. A total of 101 synthetic peptides were tested in each transgenic line of mice. HLA-DQ8 mice responded to 15 synthetic peptides representing all cyanogen bromide fragments. In contrast, HLA-DQ6 mice responded to a subset of the peptides recognized by HLA-DQ8 T cells. HLA-DQ8beta6alpha mice, although exhibiting diminished responses to the majority of HLA-DQ8-restricted determinants, elicited enhanced responses to two peptides. In addition, HLA-DQ8beta6alpha mice respond to two unique peptide determinants contained within cyanogen bromide fragments CB10 and CB11 showing the significance of mixed isotype dimers in the immune response. The determinants recognized by the HLA-DQ transgenic mice are distinct from those previously identified using conventional laboratory mice. These results suggest that human class II transgenic mice offer a means of identifying human class II-restricted epitopes associated with potential human autoantigens.

An HLA-DRB1*0402 derived peptide (HV3 65-79) prevents collagen-induced arthritis in HLA-DQ8 transgenic mice.

On the basis of our studies with HLA class II transgenic mice, we had proposed that complementation of HLA-DQ and HLA-DR alleles may determine both disease susceptibility and severity in rheumatoid arthritis (RA). According to our model, certain HLA-DQ alleles, such as HLA-DQ8, predispose individuals to RA, while a self-peptide derived from the third hypervariable region (HV3 65-79) of HLA-DR alleles, such as DRB 1*0402, can protect from disease if presented by the DQ molecule. To test this hypothesis, we examined the immunomodulatory effects of the DRB1*0402 derived peptide (HV3 65-79) on collagen-induced arthritis (CIA) in HLA-DQ8 mice. Co-immunization of the DRB 1*0402 peptide significantly reduced the severity of arthritis (mean score = 1.5+/-0.6 vs 5.2+/-1.4 in controls), whereas multiple doses of the peptide reduced the incidence of disease (3.5% vs 35-60% in controls). Subsequent analysis revealed that the DRB1*0402 peptide mediated protection may be due to the generation of a subset of regulatory cells, which down-regulate collagen-specific pro-inflammatory responses. These results provide additional insights towards understanding the role of MHC class II molecules in RA predisposition.

Modeling the lifetime costs of rheumatoid arthritis.

OBJECTIVE: To develop an analytical approach for estimating the lifetime costs of rheumatoid arthritis (RA) using existing population based cross sectional data, and to use this estimate to describe the potential cost-effectiveness of bone marrow transplantation for RA. METHODS: Estimates of arthritis related costs (direct, indirect, and nonmedical) and mortality were obtained from previously assembled population based cohorts. A mathematical model was designed defining 25 hypothetical ratios (RA/NA) representing the proportionate excess cost of RA each year for the 25 years following a diagnosis of RA. Using age and sex-specific cost estimates, we then simulated a vector of 25 ratios 1000 times. Each age and sex-specific randomly generated variable was converted to an estimated dollar amount (in 1995 dollars US) of excess cost attributable to RA. All dollar amounts were discounted by 3% per year. Finally, each vector of 25 discounted dollar amounts was summed to yield an estimate of the total excess medical costs in 1995 dollars for the first 25 years of a person's lifetime following a diagnosis of RA. Because not every one of these hypothetical individuals would be expected to live all 25 years, we used the standardized mortality ratio for an individual with RA (from our inception cohort) and multiplied it by the age-specific 1990 mortality rates for Minnesota whites to estimate how many of the 1000 randomly generated hypothetical individuals could be expected to die during each of the 25 years. For these, the summation of estimated cost was truncated at the death year. This process yielded, for each age and sex, a sample of 1000 sums of 25 (or fewer) excess costs all in terms of 1995 dollars that correspond to the excess cost during the first 25 years after an RA diagnosis, adjusted for differential survival among patients with RA compared to nonarthritic controls. The distribution of these sums thus represented a distribution of the 1995 dollars that could be saved if RA could be "cured" soon after incidence. RESULTS: Our simulation analyses indicated that the median lifetime incremental costs of RA range roughly from ,$61,000 to $ 122,000. Incremental costs were higher for younger individuals compared to older individuals and were consistent over all percentiles and age groups. No systematic relationship between the incremental costs of females with RA compared to males was identified. CONCLUSION: These data suggest that interventions such as autologous bone marrow transplantation, which has recently been estimated to cost roughly $60,000, may be cost saving if they eliminate the downstream incremental costs of RA.

Peptide binding alpha1alpha2 domain of HLA-B27 contributes to the disease pathogenesis in transgenic mice.

Human spondyloarthropathies are strongly associated with a major histocompatibility complex (MHC) class I allele, HLA-B27. HLA-B27 transgenic mice and rats demonstrate many features of these diseases further confirming the role of HLA-B27 in disease. Yet the exact role of this molecule in disease pathogenesis is not clearly understood. We have previously reported spontaneous arthritis and nail disease in HLA-B27 transgenic mice lacking beta2-microglobulin (B27+beta2m(o)). These observations along with binding studies of B27 derived peptides to HLA-B27 molecule itself led to two hypotheses: (i) HLA-B27 derived peptide as a source of autoantigen; and (ii) HLA-B27 functions as an antigen presenting molecule. In this report, we confirm spontaneous disease in transgenic mice expressing a hybrid B27 molecule with alpha1alpha2 domain of B27 and alpha3 domain of mouse H-2Kd. These mice developed spontaneous arthritis and nail disease when transferred from specific pathogen free barrier facility to the conventional area. Other control mice with MHC class I transgene (e.g., HLA-B7, HLA-Cw3, and H2-Dd) did not develop such disease. In a MHC reassembly assay, binding of similar peptides to both wild type and hybrid B27 molecules was observed. In addition, the hybrid B27 molecule lacks at least one of the 3 proposed peptides from the third hypervariable (HV3) region of HLA-B27. These data strongly suggest that HLA-B27 molecule is an antigen presenting molecule rather than a peptide donor in the disease pathogenesis.

HLA-DQ6/8 double transgenic mice develop auricular chondritis following type II collagen immunization: a model for human relapsing polychondritis.

We have generated transgenic (tg) mice expressing HLA-DQ8alphabeta (DQA1*0301/DQB*0302) or HLA-DQ6alphabeta (DQA1*0103/DQB1*0601) molecules lacking endogenous murine class II expression (A beta0) to investigate the ability of these HLA class II to present type II collagen (CII) and induce collagen-induced arthritis. The DQ8alphabeta tg mice responded strongly to CII, developing severe arthritis, while DQ6alphabeta tg mice were nonresponsive to CII. The addition of the mixed haplotype DQ8alpha6beta molecule did not significantly influence CII reactivity. To examine the interaction of DQ6alphabeta and DQ8alphabeta molecules in vivo, we generated double tg DQ6alphabeta/8alphabeta (A beta0) mice expressing both the alpha- and beta-chains of DQ6 and DQ8 molecules by mating DQ6alphabeta (A beta0) and DQ8alphabeta (A beta0) tg mice. CII-immunized DQ6alphabeta/8alphabeta tg mice developed severe experimental polychondritis, exhibiting both polyarthritis and auricular chondritis. The clinical, serologic, and histologic manifestations of experimental polychondritis are similar to those symptoms in human relapsing polychondritis. The susceptibility of DQ6alphabeta/8alphabeta tg mice compared with resistance in the parental strains suggests that expression of both the DQ6alphabeta and DQ8alphabeta tgs, unique to the DQ6alphabeta8alphabeta tg strain, is important in susceptibility to experimental polychondritis. The DQ6alphabeta/8alphabeta tg mice provide a model to investigate putative autoantigens and the mechanisms of pathogenesis involved in relapsing polychondritis as well as the influence of the expression of multiple HLA class II molecules on the disease process.

Modulation of HLA-DQ-restricted collagen-induced arthritis by HLA-DRB1 polymorphism.

Mouse class II-deficient HLA-DQB1*0302, DQA1*0301 (DQ8) transgenic mice are susceptible to severe collagen-induced arthritis (CIA), an animal model for rheumatoid arthritis. To examine whether polymorphism at the DRB1 locus can modulate DQ-restricted arthritis, we generated double-transgenic (DR/DQ) mice. HLA-DRB1*1502 (DR2) and DRB1*0301 (DR3) were introduced separately into CIA susceptible DQ8.Abeta transgenic mice to generate DQ8/DR2.Abeta and DQ8/ DR3.AbetaO mice. The HLA-DR molecules in these mice were found to be functional on the basis of their positive/negative selection of the Vbeta T cell repertoire. Introduction of the DR2 gene led to a significant decrease in disease incidence in DQ8.Abeta mice, while the DR3 transgene had no effect. In vitro T cell proliferative responses against bovine Cll collagen in primed mice were higher in DQ8/DR3 mice compared with DQ8/DR2 mice. Cytokine analysis showed a Th2 profile in DQ8/DR2 mice, while DQ8/DR3 mice showed a Th1 profile. These results suggest that DRB1 polymorphism can modulate the disease.

HLA-B27 and other predisposing factors in spondyloarthropathies.

Studies from around the world have confirmed the association between HLA-B27 and human spondyloarthropathies. The onset of many HLA-B27-linked arthritides follows an infection with enterobacteria. How bacteria interact with HLA-B27 and modify the immune system to give rise to the clinical disease is currently unclear. The roles of other genetic factors, including major histocompatibility complex class II genes and other genes located within this region (Tap/Lmp), have been postulated in certain spondyloarthropathies. We are using transgenic and knockout mice to answer some of these unsolved issues. This review discusses recent findings from our laboratories.

Spontaneous inflammatory disease in HLA-B27 transgenic mice is independent of MHC class II molecules: a direct role for B27 heavy chains and not B27-derived peptides.

Although association of HLA-B27 with human spondyloarthropathies has been known for several years, its role in disease pathogenesis is not understood. Recently, a few investigators have proposed that presentation of B27-derived peptides by MHC class II molecules may be the underlying mechanism. HLA-B27 transgenic rat and mouse models have provided a new tool for understanding the exact role of B27 in disease pathogenesis. HLA-B27 mice lacking endogenous beta2-microglobulin (B27+ beta2m(o)) develop disease after they are transferred from the barrier facility to the conventional colony. This model was utilized to test the hypothesis that B27-derived peptide presented by MHC class II molecules is the cause of the disease. The MHC class II knockout gene, A beta(o), was bred into our B27+ beta2m(o) mice, and disease manifestation was monitored. These mice develop spontaneous disease, demonstrating that MHC class II molecules do not play a major role in B27-related disease. Thus, the disease is not manifested by presentation of B27-derived peptides by class II molecules, since these mice are devoid of H2-A and H2-E molecules. Furthermore, in vivo treatment with mAb against the heavy chain of B27 reduced the incidence of disease in B27+ beta2m(o) mice. Our results clearly demonstrate that B27 heavy chains are directly involved in the disease process.

Unraveling the mystery of HLA-B27 association with human spondyloarthropathies using transgenic and knock out mice.

Human spondyloarthropathies have a strong association with the presence of MHC class I allele, HLA-B27. Spondyloarthropathies occur predominantly in males and are usually triggered by an infection with an enterobacteria. Similar to human disease, experimental animals with HLA-B27 transgene also develop spontaneous inflammatory disease. In addition to HLA-B27, the role of environmental antigens has also been implicated in the animal models. How bacteria interact with HLA-B27 is not yet clearly understood. By breeding HLA-B27 transgenic mice with various transgenic and knock out mice, we investigated the immune mechanism in this inflammatory disease. In this review, we will summarize our recent findings and propose a hypothesis.

Animal models of human leukocyte antigen B27-linked arthritides.

The major histocompatibility complex class I allele human leukocyte antigen (HLA) B27 is strongly associated with human spondyloarthropathies. To date, 12 subtypes of HLA-B27 are known and most of them are linked with human spondyloarthropathies in different ethnic populations. Although these subtypes differ from each other by a few amino acids, the have an identical B pocket in the base of the antigen-binding groove. Considering the structure of HLA-B27 subtypes and their peptide binding specificity, it is important to consider their role as antigen-presenting molecules. Many B27-linked diseases begin after an infection with an enterobacteria, suggesting a role for environmental antigens in addition to an HLA-B27 molecule. To delineate the role of infection, studies have been carried out in animal models of reactive arthritidis. More recently, transgenic animal models have been used to understand the handling of environmental antigens by HLA-B27 molecule. This article discusses some of these transgenic and nontransgenic animal models of human diseases.

HLA-DQB1 polymorphism determines incidence, onset, and severity of collagen-induced arthritis in transgenic mice. Implications in human rheumatoid arthritis.

Certain HLA-DR alleles have been associated with predisposition to human rheumatoid arthritis (RA). There is also evidence that certain HLA-DQ alleles may also be important in determining susceptibility to RA. We have previously demonstrated that mice transgenic for HLA-DQ8, a DQ allele associated with susceptibility to RA, develop severe arthritis after type II collagen immunization. To investigate the influence of polymorphic difference at the DQ loci on susceptibility to arthritis, we generated mice transgenic for HLA-DQ6, an allele associated with a nonsusceptible haplotype. The DQ6 mice were found to be resistant to collagen-induced arthritis. We also assessed the combined effect of an RA-susceptible and an RA nonassociated DQ allele by producing double-transgenic mice expressing DQ6 and DQ8 molecules, representing the more prevalent condition found in humans where heterozygosity at the DQ allele is common. The double-transgenic mice developed moderate CIA when immunized with CII when compared with the severe arthritis observed in DQ8 transgenic mice, much like RA patients bearing both susceptible and nonsusceptible HLA haplotypes. These studies support a role for HLA-DQ polymorphism in human RA.

Expression of the H2-E molecule mediates protection to collagen-induced arthritis in HLA-DQ8 transgenic mice: role of cytokines.

Transgenic mice expressing DQA1*0301 and DQB1*0302 (HLA-DQ8) molecules in class II-deficient Ab degree mice are susceptible to collagen-induced arthritis (CIA). To evaluate the role of the H2-E molecule (a homolog of HLA-DR) in DQ-restricted arthritis, the H2-E gene was introduced into DQ8.Ab degree mice to generate DQ8/E+.Ab degree mice. Expression of the E molecule protects DQ8.Ab degree mice against arthritis. In vitro studies using draining lymph nodes from mice primed with bovine type II collagen (BII) showed that the response to BII in both transgenics is DQ and CD4 restricted. Challenge with BII in vitro leads to production of high levels of IFN-gamma in DQ8 and IL-4 in DQ8/E+ mice. We have hypothesized that the H2-E molecule modulates the T cell repertoire and changes the cytokine balance, resulting in protection of disease.