HLA polymorphisms and T cells in rheumatoid arthritis

A dense infiltrate of activated T cells, macrophages, and B cells in the synovial membrane is the cardinal pathological feature of rheumatoid arthritis (RA). Frequently, tissue infiltrating cells acquire a morphological organization reminiscent of secondary lymphoid tissue. The composition of the inflammatory lesions, the production of autoantibodies, and the association of disease risk with genes related to the HLA-D region have all been cited as evidence for a critical role of T cells in disease pathogenesis. Investigations on the precise role of HLA genes in RA have confirmed the importance of this genetic risk factor and have identified a consensus sequence within the HLA-DRBI genes. The observation that HLA polymorphisms are mostly associated with disease progression and severity and that a gene dose effect for HLA-DR genes is operational has challenged the simple model that HLA molecules select and present an arthritogenic antigen. Studies analyzing the repertoire of tissue infiltrating T cells have not been able to identify a dominant and common disease relevant T cell. The infiltrate is diverse in terms of T cell receptor gene usage but consistently includes clonally expanded populations. Recent evidence indicates that RA patients carry expanded CD4 clonotypes which are characterized by deficient CD28 expression and autoreactivity. These autoreactive CD4 T cells are not restricted to the joint, raising the possibility that rheumatoid synovitis is a manifestation of a systemic autoimmune disease. Support for this model has come from studies in T cell receptor (TCR) transgenic animals which develop inflammation of the synovial membrane stimulated by a T cell response to ubiquitously expressed self-MHC molecules. Antigens driving the chronic persistent immune response in RA may not be restricted to the joint but rather may be widely distributed, providing an explanation for the difficulties in identifying arthritogenic antigens directly or indirectly through the selection of joint infiltrating T cells.     

The role of T cells in rheumatoid arthritis

In rheumatoid arthritis (RA), T cells infiltrate into the synovial membrane where they initiate and maintain activation of macrophages and synovial fibroblasts, transforming them into tissue-destructive effector cells. The diversity of the disease process and the formation of complex lymphoid microstructures indicate that multiple T cell activation pathways are involved. This model is supported by the association of distinct disease patterns with different variants and combinations of HLA class II molecules. T cell pathology in RA, however, is not limited to the joint. Affected patients have major abnormalities in the T cell pool, with a marked contraction in T cell receptor diversity and an outgrowth of large clonal populations. Clonally expanded CD4+ T cells lose expression of the CD28 molecule and gain expression of perforin and granzyme. Consequently, the functional profile of expanded CD4(+)CD28null T cells is fundamentally changed and is shifted towards tissue-injurious capabilities. CD4(+)CD28null T cells are particularly important in patients with extra-articular manifestations of RA, where they may have a direct role in vascular injury. Understanding the mechanisms underlying the loss of T cell diversity and the emergence of pro-inflammatory CD4(+)CD28null T cell clonotypes may have implications for other autoimmune syndromes.     

T cell receptor gene in synovial tissues of rheumatoid arthritis

Rheumatoid arthritis is a chronic and destructive autoimmune joint disease characterized by inflammation of synovial tissue of unknown aetiology. Studies on TCR genes expressed by infiltrating T cells in synovial tissues have attempted to identify mechanism and specificity of the recruitment. T cell infiltrate in rheumatoid arthritis appears to be an association of a polyclonal non specific infiltrate with dominant clones or clonotypes. T cell repertoire in synovial tissue is biased compared to peripheral blood but no TCR V gene can be identified as commonly over-used. Comparison of motifs found in the CDR3 region of dominant clones from different studies has currently failed to identified a commonly motif. The fact that a number of dominant clones or clonotypes is present in different joints and at different times of the disease suggests a selective expansion of T lymphocytes in rheumatoid arthritis synovial membrane. Further investigations are needed to characterize the specificity of these dominant clonotypes.     

T Cell Receptor Gene in Synovial Tissues of Rheumatoid Arthritis

Rheumatoid arthritis is a chronic and destructive autoimmune joint disease characterized by inflammation of synovial tissue of unknown aetiology. Studies on TCR genes expressed by infiltrating T cells in synovial tissues have attempted to identify mechanism and specificity of the recruitment. T cell infiltrate in rheumatoid arthritis appears to be an association of a polyclonal non specific infiltrate with dominant clones or clonotypes. T cell repertoire in synovial tissue is biased compared to peripheral blood but no TCR V gene can be identified as commonly over-used. Comparison of motifs found in the CDR3 region of dominant clones from different studies has currently failed to identified a commonly motif. The fact that a number of dominant clones or clonotypes is present in different joints and at different times of the disease suggests a selective expansion of T lymphocytes in rheumatoid arthritis synovial membrane. Further investigations are needed to characterize the specificity of these dominant clonotypes.

Synovial T cell infiltrate in rheumatoid arthritis appears to be polyclonal and the majority of T cells are non-specifically recruited into sites of inflammation following tissue injury. But almost all the studies show the presence of a large number of dominant clones in the synovial tissue, using different TCR V genes, which certainly play an important role in the perpetuation of the disease. This, and the fact that a number of dominant clones or clonotypes is present in different joints and at different times of the disease, strongly suggest a selective expansion of T lymphocytes in synovial membrane. Comparison of motifs found in the CDR3 region of dominant clones from different studies is difficult as of the number of TCRs analysed is generally low and the HLA-DR differs from patient to other. To further investigate TCR in RA, identification of the pathogenic clonotypes would be the first step before characterization of CDR3 regions of dominant clonotypes. Although the target or the auto-antigens involved in the disease have not yet been identified, sequence analyses of the CDR3 regions of dominant clonotypes could, in the future, give important informations about peptides that are the targets of auto-reactive T cells.     

Clonality of T lymphocytes expanded with IL-2 from rheumatoid arthritis peripheral blood,synovial fluid and synovial membrane

The association of rheumatoid arthritis (RA) with particular MHC class II genes suggests that autoantigen-spccific T cell clones present in joints could be central to the pathogenesis of the disease. Previous investigations on the clonal diversity of T cells infiltrating the rheumatoid synovial membrane have yielded conflicting results. With the use of Southern blot analysis, we investigated the clonalily of rheumatoid T cell lines expanded from peripheral blood, synovial fluid and synovial tissue. From peripheral blood lymphocyte (PBL) of RA patients and healthy normal controls, we also checked the consequences of two different culture conditions on the clonality of these cell lines. From control PBL, we found that in vitro non-specific expansion of non-clonal T cell populations does not create artefactual clonal selection. However, growing T cells in ritro with IL-2 seems to be able to lead to preferential expansion of cells bearing IL-2 receptor (IL-2R). We identified such in vivo activated IL-2-sensitive T cell clones frequently in RA synovial tissue (8/13) and more rarely in synovial fluid and peripheral blood (3/12). One patient presents the same T cell receptor gene rearrangements in synovial membrane of two affected joints. In RA synovial tissue, the frequency of these IL-2-responsive T cells is most prevalent among actively inflamed membranes removed early in the disease process. The role and the relevance to the disease of these I L-2-responsivc T cells remain to be elucidated.     

T Cell Receptor Repertoire in Rheumatoid Arthritis

CD4⁺ T cells are a major component of the inflammatory infiltrate in rheumatoid synovitis. Within synovial lesions, clonal CD4⁺ T cell populations are detectable, supporting the notion of an antigen specific recognition event in the joint. In general, the clonal size of individual T cell clones is small and does not lead to a marked distortion of the synovial T cell receptor (TCR) repertoire. Comparison of TCR sequences derived from different patients has not provided evidence for common sequences. Either multiple antigens are recognized or the TCR repertoire is sufficiently plastic with a multitude of different TCR structures responding to the same antigen(s). However, within one individual, the repertoire of clonal T cell populations is restricted. Identical T cell clones can be identified in different joints and at different timepoints of the disease, emphasizing that the spectrum of antigens recognized is conserved over time and that the T cell response pattern is not subject to evolution. Characterization of antigens involved in the latter stages of the disease may thus provide critical information on disease-initiating events.

Recent data have led to the new concept that the role of T cells in rheumatoid arthritis (RA) is not limited to synovial inflammation. Evidence has been provided that the premorbid TCR repertoires of RA patients and normal controls can be distinguished. The T cell repertoire in RA patients is prone to recognize certain microbial products and autoantigens. The selection of this response pattern can only partially be attributed to the disease associated HLA-DRB1 alleles. Additional factors common in RA patients but not in HLA-DR matched control individuals seem to be important in shaping the TCR repertoire. Furthermore, the repertoire of mature T cells in RA patients is characterized by oligoclonality which involves T cells in the peripheral blood compartment. Possibly, these clonal T cell populations react to widespread autoantigens, raising the possibility that RA patients have a defect in controlling peripheral tolerance and an anomaly of lymphoproliferation. In contrast to joint residing CD4⁺T cells, expanded clonotypes isolated from the blood of different patients have been described to share TCRβ chain structures. How these characteristic features of the global TCR repertoire in RA patients translate into mechanisms of disease remains to be elucidated.     

T cell receptor repertoire in rheumatoid arthritis

CD4+ T cells are a major component of the inflammatory infiltrate in rheumatoid synovitis. Within synovial lesions, clonal CD4+ T cell populations are detectable, supporting the notion of an antigen specific recognition even in the joint. In general, the clonal size of individual T cell clones is small and does not lead to a marked distortion of the synovial T cell receptor (TCR) repertoire. Comparison of TCR sequences derived from different patients has not provided evidence for common sequences. Either multiple antigens are recognized or the TCR repertoire is sufficiently plastic with a multitude of different TCR structures responding to the same antigen(s). However, within one individual, the repertoire of clonal T cell populations is restricted. Identical T cell clones can be identified in different joints and at different timepoints of the disease, emphasizing that the spectrum of antigens recognized is conserved over time and that the T cell response pattern is not subject to evolution. Characterization of antigens involved in the latter stages of the disease may thus provide critical information on disease-initiating events. Recent data have led to the new concept that the role of T cells in rheumatoid arthritis (RA) is not limited to synovial inflammation. Evidence has been provided that the premorbid TCR repertoires of RA patients and normal controls can be distinguished. The T cell repertoire in RA patients is prone to recognize certain microbial products and autoantigens. The selection of this response pattern can only partially be attributed to the disease associated HLA-DRB1 alleles. Additional factors common in RA patients but not in HLA-DR matched control individuals seem to be important in shaping the TCR repertoire. Furthermore, the repertoire of mature T cells in RA patients is characterized by oligoclonality which involves T cells in the peripheral blood compartment. Possibly, these clonal T cell populations react to widespread autoantigens, raising the possibility that RA patients have a defect in controlling peripheral tolerance and an anomaly of lymphoproliferation. In contrast to joint residing CD4+ T cells, expanded clonotypes isolated from the blood of different patients have been described to share TCR beta chain structures. How these characteristic features of the global TCR repertoire in RA patients translate into mechanisms of disease remains to be elucidated.     

The molecular basis of rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disease targeting the synovial membrane and extra-articular tissues. The most feared consequences are significant levels of pain, functional disability, and rheumatoid organ involvement. Molecular investigations of RA have markedly changed the understanding of the pathogenesis although the etiology remains unresolved. Despite the failure of intense efforts to confirm the presence of an infectious micro-organism in rheumatoid synovium, the concept that RA is infectious in origin has continued to be attractive. Theories on the autoimmune nature of RA have benefited from the enormous progress made in understanding the cellular and molecular components of normal immune responses. However, convincing experimental evidence of a joint-specific endogenous antigen in the synovial lesions is still lacking. The viewpoint that RA represents the sequelae of systemic lymphoproliferation has recently been supported by the finding of autoreactive T cells with atypical growth and differentiation behavior. Significant cross-fertilization for the understanding of RA can be expected by studies elucidating cell cycle control and the role of proto-oncogenes. The realization that RA is a genetic disease has had and will have a major impact on investigating pathological events. As in other common genetic disorders, multiple genetic determinants contribute to the risk of an individual developing chronic inflammatory rheumatoid synovitis. Individual genetic elements are seldom mutated or abnormal, but a risk threshold is reached by their accumulation and combination. Genes encoded in the HLA region are recognized as RA risk genes. Recent studies have emphasized that a gene dosing effect for RA-associated HLA alleles is functional, and that HLA polymorphisms act as progression factors rather than as initiation factors in the disease process. These data have challenged the traditional paradigm that disease-associated HLA molecules function solely through their capability to select, bind, and present an arthritogenic antigen. Current efforts focus on identifying the spectrum and nature of genes associated with various RA phenotypes. The future will likely see a broadening of biological systems involved in the pathogenesis of RA with anomalies other than immunoresponsiveness contributing to mechanisms driving articular and extra-articular RA.     

Morphological and molecular pathology of the B cell response in synovitis of rheumatoid arthritis

The synovitis of rheumatoid arthritis (RA) was long regarded merely as an unspecific chronic inflammatory process of minor diagnostic value and therefore did not play a major role in the understanding of the pathogenesis of RA. It is only in recent years, along with the observation that T and B cells are expanded oligoclonally in synovial tissue and that B cells are able to undergo a local germinal center (GC) reaction, that the synovial tissue has come to be regarded as a site of specific immune processes. The analysis of the immunoglobulin (Ig) gene repertoire had great impact on the understanding of B cell response in lymphatic organs and was subsequently applied to B cells from RA patients. The analyses of the variable (V) regions of the Ig heavy (H) and light (lambda) chains suggested that an antigen specific activation and differentiation of B cells into plasma cells (Plc) takes place in the chronically inflamed synovial tissue of patients with RA. It seems that in a subset of RA patients the synovial tissue develops into an ectopic lymphoid tissue that supports a local GC reaction. Ectopic GC are characteristic of RA; however, they are in general absent from synovitis of osteoarthritis (OA). Here the accumulation of Plc follows a different mechanism. Highly mutated VH genes suggest that in OA memory B cells migrate into the synovial tissue with subsequent differentiation into Plc but without further V gene diversification. Therefore in synovitis two patterns of B cell activation can be differentiated: the maturative and the accumulative type. These two patterns are not definitely disease linked. The maturative type is only found in RA whereas the accumulative type occurs in both diseases. Clinically RA is defined via serum antibodies to the constant region of Ig, so-called rheumatoid factor. However, the spectrum of autoreactive B cells in RA patients is wide and is based on the study of antibody specificities in serum, in synovial fluid and B cell lines derived from peripheral blood, bone marrow, synovial fluid and synovial tissue. These analyses defined non-organ-specific and organ-specific antigens. One can reasonably assume that the disease is far too complex to be explained by only a single antigen. There is a whole combination of antigens acting in a multistep manner that is responsible for RA pathogenesis. It can be hypothesized that chronic synovitis, which is the underlying mechanism of joint destruction, follows a three-step process: (a) initiation, (b) destruction, and (c) perpetuation. The characterization of antigens driving the local synovial B cell maturation and accumulation could lead to an understanding of the process perpetuating the disease. Identification of arthritogenic antigens may yield new avenues for diagnostics and immunotherapy but also a new approach for prevention by vaccines with antigens probably defined by synovial B cell reactivity.     

Characterization of tissue outgrowth developed in vitro in patients with rheumatoid arthritis: involvement of T cells in the development of tissue outgrowth

BACKGROUND: The aim of this study was to analyze cellular and cytokine interactions governing the development of synovial tissue outgrowth in patients with rheumatoid arthritis (RA). METHODS: A single-cell suspension of dissociated synovial tissues of RA patients was cultured for a long period to develop tissue outgrowth. The resulting tissue outgrowth was characterized by immunohistochemical staining and ELISA. RESULTS: The tissue outgrowth developed in vitro included various cell types, such as macrophage-like synovial cells, fibroblast-like synovial cells and lymphocytes. Even after prolonged cultivation, synovial cells devoid of infiltrating T lymphocytes did not form tissue outgrowth. The outgrowth contained CD3+ cells, LeuM3 (CD14)+ cells and HLA-DR+ cells. The T cells expressed lymphocyte function-associated antigen (LFA)-1 and CD2, and the synovial cells expressed intracellular adhesion molecule (ICAM)-1 and LFA-3, suggesting possible interactions via LFA-1/ICAM-1 and CD2/LFA-3. Production of T-cell derived IFN-gamma and IL-17 and synovial-cell-derived fibroblast growth factor (FGF)-1 and IL-15 was confirmed in the tissue outgrowth as well as in RA synovial tissue. These cell types stimulate each other by secreting cytokines, leading to the secretion of proinflammatory cytokines and matrix metalloproteinase (MMP)-1 by the tissue outgrowth and proliferation of both lymphocytes and synovial cells. CONCLUSION: This study emphasizes the importance of cellular interactions between T cells and synovial cells, via adhesion molecules and the secretion of cytokines with stimulatory activity towards other cell types, for the hyperactivity of RA synovial cells.     

Immunoglobulin heavy chain variable region gene utilization by B cell hybridomas derived from rheumatoid synovial tissue.

Rheumatoid arthritis (RA) is a chronic inflammatory disease that primarily affects synovial joints. Activated B lymphocytes and plasma cells are present in the synovial tissue and are thought to contribute to the immunopathology of the rheumatoid joint. To investigate rheumatoid synovial B lymphocytes, we have generated B cell hybridomas from synovial tissue of an RA patient. Here we describe the immunoglobulin VH gene repertoire of eight IgM- and 10 IgG-secreting synovial-derived hybridomas. The VH4 gene family is highly represented (38.5%) in this panel of hybridomas compared with the frequency of VH4 gene expression in circulating B lymphocytes reported previously (19-22%) and with the VH4 gene frequency we observed in a panel of hybridomas derived in the same manner from the spleen and tonsil of normal individuals (19%). The increased frequency of VH4 gene expression was not due to the expansion of a single B cell clone in vivo as none of these hybridomas was clonally related. Two synovial-derived hybridomas secreted autoantibodies; one (VH3+) secreted an IgM-rheumatoid factor (RF) and the other (VH4+) secreted IgM with polyreactive binding to cytoskeletal proteins and cardiolipin. The antibodies secreted by the remaining synovial-derived hybridomas were not reactive with the autoantigens tested. The VH gene usage in a proportion (5/17) of synovial-derived hybridomas that expressed CD5 antigen provided preliminary evidence that CD5+ B cells in RA synovium have a similar increase of VH4 gene expression reported for CD5+ B cells from normal individuals and patients with chronic lymphocytic leukaemia.     

Skewed T-cell receptor BV14 and BV16 expression and shared CDR3 sequence and common sequence motifs in synovial T cells of rheumatoid arthritis

T-lymphocytes play an important role in rheumatoid arthritis (RA). In this study, we evaluated the hypothesis that common T-cell receptor (TCR) structural features may exist among infiltrating T cells of different RA patients, if the TCR repertoire is shaped by interaction with common self or microbial antigens in the context of susceptible HLA genes in RA. Synovial lesion tissue (ST), synovial fluid (SF) and blood specimens from RA patients and controls were analyzed for TCR V gene repertoire by real-time PCR. There was highly skewed BV14 and BV16 usage in synovial T cells of RA as opposed to those of controls, which was accompanied with a trend for correlation between skewed BV16 and DRB1(*)0405. Immunoscope analysis of the V-D-J region of ST-derived T cells demonstrated oligoclonal and polyclonal expansion of BV14(+) and BV16(+) T cells. Detailed characterization using specific BV and BJ primers further revealed common clonotypes combining the same BV14/BV16, BJ and CDR3 length. DNA cloning and sequence analysis of the clonotypes confirmed identical CDR3 sequences and common CDR3 sequence motifs among different RA patients. The findings are important in the understanding of BV gene skewing and CDR3 structural characteristics among synovial infiltrating T cells of RA.     

Interleukin-15 induces interleukin-17 production by synovial T cell lines from patients with rheumatoid arthritis

IL-17-producing T cells (Th17 cells) are believed to contribute to local inflammation and joint damage in rheumatoid arthritis (RA). Limited data exist on Th17 cells located within the inflamed synovial tissue (ST) of patients with RA. Here, we aimed to generate polyclonal T cell lines (TCLs) from the RA ST and assess their cytokine production, including the effects of exogenous IL-15 on IL-17 production in vitro. For five patients with RA, polyclonal TCLs were established from ST obtained by joint surgery. Synovial TCLs were expanded and stimulated by anti-CD3/CD28 microbeads and exogenous cytokines. Cytokine production was assessed by culture supernatant analyses and intracellular flow cytometry, and TCLs were sorted based on their surface expression of CCR6. In addition to IL-17, we detected IL-6, IL-10, IFN-γ and TNF-α in the synovial TCL culture supernatants. Exogenous IL-15 increased the production of IL-17 as well as the other cytokines except IFN-γ. For IL-17, this effect was more pronounced after prolonged culture times. Intracellular flow cytometry confirmed the presence of IL-17+ and IL-17+ IFN-γ+ CD4+ T cells in the TCLs. IL-17+ and IL-17+ IFN-γ+ T cells were enriched in the CD4+ CCR6+ population. In conclusion, Th17 cells can be detected after polyclonal expansion and stimulation of RA synovial TCLs generated by joint surgery. The Th17 cells from the RA ST were enriched in the CD4+ CCR6+ population, and they were sensitive to exogenous IL-15. Th17 cells present within the synovial compartment may contribute to the RA pathogenesis and local joint damage.     

Synovial biology and T cells in rheumatoid arthritis.

Events that occur in rheumatoid arthritis synovial tissues are responsible for the signs and symptoms of joint inflammation and for the eventual destruction of articular and periarticular structures that lead to joint dysfunction and disability. The three most abundant cell populations in RA synovium are synovial macrophages (type A synoviocytes), synovial fibroblasts (type B synoviocytes) and infiltrating T lymphocytes. Other important cell populations include B lymphocytes, dendritic cells, plasma cells, mast cells and osteoclasts. Our current understanding of rheumatoid arthritis is moving beyond previous concepts that view this disease as the consequence of a specific and focused humoral or cellular autoimmune response to a single autoantigen. Rather, a new view of rheumatoid arthritis is emerging, which seeks to understand this disease as the product of pathologic cell-cell interactions occurring within a unique and defined environment, the synovium. T lymphocytes in rheumatoid arthritis synovium interact closely with dendritic cells, the most potent antigen-presenting cell population in the immune system. T cells also interact with monocytes and macrophages and cytokine-activated T cells may be, especially, suited to trigger production of the important cytokine TNFalpha by synovial macrophages. Recent evidence also suggests a potent bidirectional interaction between synovial T cells and synovial fibroblasts, which can lead to activation of both cell types. An important role for synovial B lymphocytes has been emphasized recently, both by experimental data and by results of clinical interventions. B cells in synovium can interact with fibroblasts as well as with other cells of the immune system and their potential role as antigen-presenting cells in the joint is as yet underexplored. Rheumatoid arthritis synovium may be one of the most striking examples of pathologic, organ-specific interactions between immune system cells and resident tissue cell populations. This view of rheumatoid arthritis also leads to the prediction that novel approaches to treatment will more logically target the intercellular communication systems that maintain such interactions, rather than attempt to ablate a single cell population.     

Heterogeneity of rheumatoid arthritis: from phenotypes to genotypes

Rheumatoid arthritis (RA) is now recognized as a multigene disorder with a number of genetic polymorphisms contributing to disease pathogenesis. Here, we propose that the diagnostic category of RA includes multiple subtypes of disease and that the different phenotypes of RA correlate to different genotypes. Support for this concept has come from a reappraisal of the clinical heterogeneity of RA and the observation that HLA-DRB 1 polymorphisms are useful in describing genetic heterogeneity of RA phenotypes. A series of HLA-DRB 1 genes has been identified as RA associated, and in recent years emphasis has been put on the sequence similarities of these alleles. An alternative view focuses on the amino acid variations found in RA-associated HLA-DRB 1 alleles with different alleles being enriched in distinct subtypes of RA. Rheumatoid factor-positive destructive joint disease is predominantly associated with the HLA-DRB1*0401 allele, while HLA-DRB 1*0404 and B1*0101 predispose for milder and often seronegative disease. Expression of disease-associated alleles on both haplotypes carries a high risk for extra-articular manifestations. In particular, patients homozygous for HLA-DRB1*0401 frequently develop rheumatoid vasculitis on follow-up. Besides HLA gene polymorphisms, abnormalities in the generation and function of CD4 T cells and in inflammatory pathways established in synovial lesions can be used to dissect patient subsets with different variants of RA. Emergence of CD28-deficient CD4 T cells identifies RA patients with extra-articular manifestations. These cells undergo clonal expansion in vivo, produce high amounts of IFN-, and exhibit autoreactivity. Concordance of monozygotic twins for the expression of CD4⁺ CD28^– T cells suggests a role for genetic factors in the generation of these unusual T cells. Evidence for heterogeneity of the synovial component of RA comes from studies describing three distinct patterns of lymphoid organization in the synovium. Based upon the topography of tissue-infiltrating mononuclear cells, diffuse, follicular, and granulomatous variants of rheumatoid synovitis can be distinguished. Each pattern of lymphoid organization correlates with a unique profile of tissue cytokines, demonstrating that several pathways of immune deviation modulate disease expression in RA. A dissection of RA variants would have major implications on how the disease is studied, treated, and managed. Identifying combinations of RA risk genes that correlate with disease variants could, therefore, become an important diagnostic tool.     

L-Selectin Expression on the Surface of Peripheral Blood Leucocytes from Rheumatoid Arthritis Patients is Linked to Disease Activity

Recruitment of mononuclear cells from the circulation to sites of inflammation relies on migration across vessel endothelium. T and B cells, macrophages and neutrophils infiltrate synovial tissue of rheumatoid arthritis (RA) patients. The authors have analysed the numbers of circulating CD3⁺, CD19⁺ lymphocytes, monocytes, and granulocytes expressing adhesion molecules (L-selectin, CD44 and CD11a), together with levels of expression in RA patients compared to healthy individuals. Numbers of leucocytes expressing the adhesion molecules detected were similar in RA and control groups. Lower levels of expression of L-selectin on all cells were found in RA patients compared to controls. Expression of L-selectin on T and B cells was found to correlate with disease activity in RA. The authors have observed a characteristic pattern of adhesion molecule expression in RA patients, particularly when analysing the relationships between cells. The close regulation of these molecules between RA patients and healthy individuals is discussed.     

Collagen Arthritis in Rats,Arthritogenic Lymphokines and Other Aspects

This review will mainly highlight data from selected, independent studies which collectively implicate a primary role for T cells in the pathogenesis of collagen arthritis in rats. Conferring insusceptibility to this experimental disease with the use of polyclonal, T cell specific antiserum provided direct initial evidence for this conclusion. Substantiation for the theory of a dominant T cell role in collagen arthritis was afforded by T cell line vaccination; scrutiny showed that the mechanism accounting for this protection was a specific down-regulation of the cellular response to collagen. Additional support came from experiments which showed that as few as 10³ type II collagen specific T line cells were capable of provoking a sustained proliferative synovitis when instilled into the knee joint cavity of syngeneic naive rats. Further analysis of this phenomenon revealed that the arthritogenic capacity of various collagen-reactive line cells correlated with their ability to release a 65-Kd, collagen-binding lymphokine. This antigen-specific lymphokine was designated arthritogenic factor, based on an arthritogenic activity in the knee joint bioassay similar to that of the cells. A functional and physicochemically identical rat arthritogenic factor has also been identified in the adjuvant model of arthritis. These data support the premise that a major effector mechanism in experimental rat arthritis is the release of arthritogenic factor by expanded clones of autoreactive T cells; they also indicate that substantive efforts should be undertaken to seek to identify arthritogenic factor-like lymphokines in patients with chronic inflammatory synovial disease. As an equally plausible alternative hypothesis, the review will close with a brief discussion of recent findings supporting the possible involvement of cartilage-binding, complement-fixing anti-type II collagen antibodies in the pathogenesis of rheumatoid arthritis.     

Evidence for the presence of activated CD4 T cells with naive phenotype in the peripheral blood of patients with rheumatoid arthritis.

We have investigated whether T cell activation in rheumatoid arthritis (RA) preferentially engages distinct T cell subpopulations in the peripheral blood (PB) and in the synovial fluid. We found that CD25 expression was enhanced among PB CD4 T cells of RA patients as compared with CD4 cells of patients with reactive arthritis, degenerative joint disease or of healthy controls. Within the CD4 T lymphocytes subset we found that the CD45RO- (naive) cells selectively in RA displayed higher levels of CD25 protein and of interferon-gamma mRNA expression when compared with the respective subset of all other investigated groups. These results show that in the PB of RA, but not in the PB of the other arthropathies or healthy controls, CD45RO-CD4 T lymphocytes exist which display well-defined signs of activation.     

Collagen arthritis in rats, arthritogenic lymphokines and other aspects

This review will mainly highlight data from selected, independent studies which collectively implicate a primary role for T cells in the pathogenesis of collagen arthritis in rats. Conferring insusceptibility to this experimental disease with the use of polyclonal, T cell specific antiserum provided direct initial evidence for this conclusion. Substantiation for the theory of a dominant T cell role in collagen arthritis was afforded by T cell line vaccination; scrutiny showed that the mechanism accounting for this protection was a specific down-regulation of the cellular response to collagen. Additional support came from experiments which showed that as few as 10(3) type II collagen specific T line cells were capable of provoking a sustained proliferative synovitis when instilled into the knee joint cavity of syngeneic naive rats. Further analysis of this phenomenon revealed that the arthritogenic capacity of various collagen-reactive line cells correlated with their ability to release a 65-Kd, collagen-binding lymphokine. This antigen-specific lymphokine was designated arthritogenic factor, based on an arthritogenic activity in the knee joint bioassay similar to that of the cells. A functional and physicochemically identical rat arthritogenic factor has also been identified in the adjuvant model of arthritis. These data support the premise that a major effector mechanism in experimental rat arthritis is the release of arthritogenic factor by expanded clones of autoreactive T cells; they also indicate that substantive efforts should be undertaken to seek to identify arthritogenic factor-like lymphokines in patients with chronic inflammatory synovial disease. As an equally plausible alternative hypothesis, the review will close with a brief discussion of recent findings supporting the possible involvement of cartilage-binding, complement-fixing anti-type II collagen antibodies in the pathogenesis of rheumatoid arthritis.