The frequency of remission and low disease activity in patients with rheumatoid arthritis, and their ability to identify people with low disability and normal quality of life

OBJECTIVE

Treat-to-target in rheumatoid arthritis (RA) recommends targeting remission, with low disease activity (LDA) being an alternative goal. When deciding to target remission or LDA, important considerations are the likelihood of attaining them, and their impacts on function and health-related quality of life (HRQoL). We have addressed this by studying: (a) the frequency of remission and LDA/remission; (b) DAS28-ESR trends after remission; (c) ability of remission vs. LDA to identify patients with normal function (HAQ ≤ 0.5) and HRQoL (EQ-5D ≥ the normal population).

METHODS

We studied 571 patients in two clinical trials, and 1693 patients in a 10-year routine care cohort. We assessed the frequency and sustainability of remission and LDA/remission, variability in DAS28-ESR after remission, and sensitivity/specificity of remission and LDA/remission at identifying patients with low disability levels and normal HRQoL using Receiver Operator Characteristic (ROC) curves.

RESULTS

Point remission and remission/LDA were common (achieved by 35-58% and 49-74% of patients, respectively), but were rarely sustained (sustained remission and remission/LDA achieved by 5-9% and 9-16% of patients, respectively). Following attaining remission, DAS28-ESR levels varied substantially. Despite this, of those patients attaining point remission, the majority (53-61%) were in remission at study end-points. Whilst remission was highly specific at identifying patients with low disability (85-91%) it lacked sensitivity (51-57%); similar findings were seen for normal HRQoL (specificity 78-86%; sensitivity 52-59%). The optimal DAS28-cut-off to identify individuals with low disability and normal HRQoL was around the LDA threshold.

CONCLUSIONS

Our findings support both the treat-to-target goals. Attaining remission is highly specific for attaining low disability and normal HRQoL, although many patients with more active disease also have good function and HRQoL. Attaining a DAS28-ESR ≤ 3.2 has a better balance of specificity and sensitivity for attaining these outcomes, with the benefit of being more readily achievable. Although sustaining these targets over time is rare, even attaining them on a one-off basis leads to better function and HRQoL outcomes for patients.

Infliximab improves vascular stiffness in patients with rheumatoid arthritis

Objectives:

Patients with rheumatoid arthritis (RA) have increased cardiovascular mortality. Tumour necrosis factor α (TNFα)-blocking therapy has been shown to reduce RA disease activity measures and joint damage progression. Some observational studies suggest that TNFα blockade reduces mortality and incidence of first cardiovascular events. The mechanisms contributing to these outcomes are unclear. This study assessed the effects of infliximab treatment on vascular stiffness and structure in patients with RA.

Methods:

A post hoc analysis of longitudinal data from a randomised placebo controlled study evaluated the effect of infliximab on vascular assessments. 26 patients received intravenous infliximab (3 mg/kg) at weeks 0, 2, 6 and every 8 weeks thereafter to week 54. Patients were followed up to 56 weeks of infliximab therapy with assessments of RA disease activity, cardiovascular risk factors, vascular stiffness (pulse wave velocity (PWV)), carotid intima media thickness (CIMT) and carotid artery plaque (CAP). Univariate analyses of changes over time by repeated measures analysis of variance (ANOVA) were followed by multivariate time-series regression analysis (TSRA) if changes were seen.

Results:

PWV was significantly lower (better) after 56 weeks of treatment with infliximab (ANOVA p<0.01, TSRA p<0.01). However, CIMT (ANOVA p = 0.50) and CAP (χ² = 4.13, p = 0.88) did not change over the study period. Multiple cardiovascular risk measures did not change with treatment and did not correlate with changes in measures of vascular structure.

Conclusions:

Arterial stiffness improves with infliximab treatment in RA. This change may help explain the improved cardiovascular disease survival in patients with RA receiving TNFα-blocking therapy.

Adalimumab in clinical practice. Outcome in 70 rheumatoid arthritis patients, including comparison of patients with and without previous anti-TNF exposure

OBJECTIVE

To assess the efficacy and safety of the fully human recombinant monoclonal anti-TNF antibody adalimumab in routine clinical practice, including comparison of patients with and without previous anti-TNF exposure.

METHODS

We prospectively studied the outcome of 70 rheumatoid arthritis patients treated with adalimumab in normal clinical practice. The primary outcome measures were Disease Activity Score 28 (DAS28), EULAR (European League Against Rheumatism) response and Health Assessment Questionaire (HAQ).

RESULTS

Seventy-seven per cent achieved a EULAR response (26% good, 51% moderate) and 19% were in remission. The mean decrease in DAS28 was 2.1 (6.3-4.2; P<0.001). The mean decrease in HAQ score was 0.34 (2.07-1.73; P<0.001), 66% achieving a clinically significant decrease of greater than 0.22. Twenty-three per cent stopped treatment because of side-effects (7%) or failure to respond (16%). Of the 26 patients who had previously tried 29 biologicals, 65% responded to adalimumab. There was no significant difference in the change in mean DAS (P = 0.69) or HAQ (P = 0.88) between groups with and without previous anti-TNF exposure. Of the 13 patients with previous secondary failure to infliximab, 77% responded to adalimumab. Patients with previous secondary failure had significantly better improvement in DAS (P = 0.023) than patients with previous primary failure.

CONCLUSION

Our clinical experience confirms that adalimumab is effective and safe in the treatment of RA. It also shows adalimumab is effective in patients with previous biological failures, particularly patients with secondary failure to infliximab.

[Role of cell migration in the pathogenesis of rheumatoid arthritis: in vivo studies in SCID mice transplanted with human synovial membrane]

OBJECTIVE

Adhesion mechanisms play a central role in the recruitment of leukocytes which characteristically infiltrate rheumatoid synovium. Therefore, we adapted an animal model, in which human rheumatoid synovium was transplanted into severe combined immunodeficient (SCID) mice, to study the effects of Tumor Necrosis Factor-alpha (TNF-alpha) in modulatine leukocyte migration and to investigate the chemotactic potential of Stromal Derived Factor-1 alpha (SDF-1 alpha).

MATERIALS AND METHODS

Human synovium samples, obtained from patients undergoing joint replacement, were divided into two parts. One was analysed by immunohistology and the other was implanted subcutaneously into SCID mice under general anaesthesia. Four weeks post-transplantation, grafts were injected with optimal dose of SDF-1, TNF-alpha or saline (negative control). At the same time, animals were injected iv with fluorescently labelled cells. 48 hours later mice were sacrificed and grafts removed for cryo-hystology. The number of cells migrating to the grafts was determined by UV-microscopy and the results expressed as cells per high power field.

RESULTS AND CONCLUSIONS

In these studies we provide the evidence that: 1) the animal model, in which human tissues are grafted into SCID mice, can be used to study cell migration under controlled experimental conditions; 2) direct intragraft injection of TNF-alpha increases lymphocytes migration and up-regulates the expression of human adhesion molecules (CAMs) and 3) SDF-1 alphainjected intragraft increases the migration of the pro-myelo-monocytic U937 cells to synovial transplants, even more efficiently than TNF-alpha, but without modifications of CAMs' expression.

The glucocorticoid inhibition of LFA-1 and CD2 expression by human mononuclear cells is reversed by IL-2, IL-7 and IL-15

Glucocorticoids are agents endowed with powerful immunosuppressive and anti-inflammatory properties partially related to the inhibition of adhesion-related processes. We have previously demonstrated that glucocorticoids inhibit LFA-1 and CD2 expression in human peripheral blood mononuclear cells (PBMC) by down-regulating mRNA steady-state levels. In this study, we investigated whether glucocorticoids could also act indirectly by modulating the effect/function of cytokines whose expression are known to inhibit. To test this hypothesis, we replenished the following cytokines IL-2, IL-7, IL-15, TNF-alpha, IL-1beta, IL-4 and IL-10, in an in vitro PBMC culture system. Our results indicate that only the IL-2Rgamma-chain-dependent cytokines IL-2, IL-7 and IL-15, among the cytokines of this panel, could reverse the inhibition of glucocorticoids on PBMC adhesion molecule expression and the related functions of intercellular aggregation and proliferation. Furthermore, we also demonstrated that IL-2, IL-7 and IL-15 could induce de novo the synthesis of LFA-1 and CD2. Taken together, these data suggest that glucocorticoids inhibit PBMC LFA-1 and CD2 expression not only directly by modulating transcriptional events, but also indirectly through the inhibition of IL-2Rgamma-dependent cytokines.

Are differences in interleukin 10 production associated with joint damage?

OBJECTIVE

Constitutive differences between individuals in cytokine production may determine the variation in the course of inflammatory arthritis.

METHODS

The association between interleukin 10 (IL-10) production and joint destruction was studied by comparing IL-10 mRNA content in synovial biopsies from seven patients with destructive joint disease and six patients with non-destructive joint disease. The IL-10 mRNA content was 0.4 +/- 0.6 arbitrary units in erosive joints compared with 2.3 +/- 1.2 arbitrary units in non-erosive joints (P: < 0.03, Mann-Whitney U:-test). As this difference suggested that IL-10 production was associated with joint destruction, we tested whether the IL-10 locus determined the extent of joint damage.

RESULTS

Innate differences in IL-10 production are locus-dependent. In line with these data, we showed that innate differences in IL-10 protein production were also present as differences in IL-10 mRNA levels. We tested if polymorphisms in the promoter of IL-10 were associated with the extent of joint damage.

DISCUSSION

In a cohort study of female rheumatoid arthritis patients followed for 12 yr, the extent of joint destruction differed significantly between patients with different IL-10 genotypes. In patients with the -1082AA genotype who were studied prospectively, the mean increase in radiographic damage score (modified Sharp score of X-rays of hands and feet) during the first 6 yr was 9 +/- 9 per yr vs 19 +/- 16 per yr for patients with the genotype -1082GG (P: < 0.02). In line with these data, cultures of endotoxin-stimulated whole blood from 158 donors showed that the presence of the allele associated with less joint destruction correlated with slightly higher IL-10 production.

CONCLUSIONS

Both the immunogenetic and the synovial biopsies suggest that a variation in IL-10 production is associated with joint destruction.

Mechanisms of action of second-line agents and choice of drugs in combination therapy

Second-line agents are used commonly for the treatment of rheumatoid arthritis (RA). They suppress inflammation and ameliorate symptoms but often fail to substantially improve long-term disease outcome. Their use in RA was discovered serendipitously and their modes of action were largely unknown. Recent researches have identified some of their mechanisms of action. Most of them have antiinflammatory properties and some are immunomodulators. Traditionally, second-line agents are used as monotherapy, but recent evidence suggests that combination treatment with two or more drugs may be more efficacious. However, the choice of agents in combination therapy is not based on their mechanisms of action. We review current knowledge on the modes of action of second-line agents and assess whether such understanding may offer a rational basis for combination therapy.

Corticosteroids inhibit lymphocyte binding to endothelium and intercellular adhesion: an additional mechanism for their anti-inflammatory and immunosuppressive effect

Glucocorticosteroids (GCS) are potent anti-inflammatory and immunosuppressive agents widely used in the treatment of many medical conditions, but their mechanism of action is not yet fully understood. Some of the anti-inflammatory effects of GCS have been attributed to the synthesis of lipocortins, whereas the immunosuppressive effects are thought to be mediated through the inhibition of several immune functions through a down-regulation of cytokine gene expression. Another important mechanism of action of GCS may relate to their ability to interfere with the phenomena of adhesion and migration of inflammatory cells. In this study, the direct effects of GCS on lymphocyte adhesion capacity in vitro were investigated. We demonstrate that GCS inhibit lymphocyte adhesion to endothelium through the down-modulation of lymphocyte adhesion molecules. We also provide evidence that GCS inhibit cell aggregate formation induced by TCR ligation, which directly correlates with the down-modulation of LFA-1 and CD2, but not LFA-3 or ICAM-1. Such down-modulation was paralleled by a decrease in the steady state mRNA level of LFA-1 and CD2 gene products, which suggests a direct GCS control of the expression of these genes. Finally, we show that GCS effects are mediated through the GCS receptor, since they can be completely reversed by the GCS-R antagonist RU-486. This study supports the concept that some of the immunosuppressive and anti-inflammatory effects of GCS are likely to be exerted by the inhibition of adhesion-dependent lymphocyte functions.

Corticosteroids inhibit lymphocyte binding to endothelium and intercellular adhesion: an additional mechanism for their anti-inflammatory and immunosuppressive effect

Glucocorticosteroids (GCS) are potent anti-inflammatory and immunosuppressive agents widely used in the treatment of many medical conditions, but their mechanism of action is not yet fully understood. Some of the anti-inflammatory effects of GCS have been attributed to the synthesis of lipocortins, whereas the immunosuppressive effects are thought to be mediated through the inhibition of several immune functions through a down-regulation of cytokine gene expression. Another important mechanism of action of GCS may relate to their ability to interfere with the phenomena of adhesion and migration of inflammatory cells. In this study, the direct effects of GCS on lymphocyte adhesion capacity in vitro were investigated. We demonstrate that GCS inhibit lymphocyte adhesion to endothelium through the down-modulation of lymphocyte adhesion molecules. We also provide evidence that GCS inhibit cell aggregate formation induced by TCR ligation, which directly correlates with the down-modulation of LFA-1 and CD2, but not LFA-3 or ICAM-1. Such down-modulation was paralleled by a decrease in the steady state mRNA level of LFA-1 and CD2 gene products, which suggests a direct GCS control of the expression of these genes. Finally, we show that GCS effects are mediated through the GCS receptor, since they can be completely reversed by the GCS-R antagonist RU-486. This study supports the concept that some of the immunosuppressive and anti-inflammatory effects of GCS are likely to be exerted by the inhibition of adhesion-dependent lymphocyte functions.

Adhesion molecules in rheumatoid arthritis: role in the pathogenesis and prospects for therapy

The essential role played by cell adhesion and migration in the generation of chronic synovitis is now beyond doubt. Some of the beneficial effects of currently used drugs may be related to their ability to interfere with these mechanisms. The complexity of the process, however, means that there are many potential targets for therapeutic intervention and therefore further studies of the basic mechanisms are necessary to identify those which are most important.

Adverse interaction between intramuscular methylprednisolone and sulphasalazine in patients with early rheumatoid arthritis. A pilot study

A defective hypothalamic-pituitary-adrenal axis has been associated with susceptibility to arthritis in rats and with rheumatoid arthritis in humans. The effect of corticosteroid supplementation in early RA has not been tested previously. We undertook a double-blind placebo-controlled study of sulphasalazine plus either corticosteroid or placebo. No early benefit was demonstrated as 7 of 11 of the corticosteroid supplemented group had withdrawn by 1 year. The addition of corticosteroids to sulphasalazine in patients with early disease did not appear to offer any benefit.

Systemic sclerosis occurring in a patient with Adamantiades-Behçet's disease

We report a patient who developed SS while being treated with azathioprine for ABD. This is a hitherto unreported association between the two conditions.

Cellular responses to human chondrocytes: absence of allogeneic responses in the presence of HLA-DR and ICAM-1

To assess the accessory cell function of human articular chondrocytes, we assessed the ability of human chondrocytes to stimulate allogeneic peripheral blood mononuclear cells (PBMC) and to support phytohaemagglutinin (PHA)-induced proliferation of highly purified T cells. We also examined the surface expression of HLA-DR and ICAM-1 on the chondrocytes both unstimulated and stimulated with cytokines in vitro. Chondrocytes failed to stimulate allogeneic PBMC despite the constitutive expression of MHC class I molecules and the cytokine-induced expression of class II molecules but were able to support T cell proliferation to PHA, IFN-gamma and to a limited extent, IL-1 beta, induced class II expression on chondrocytes. ICAM-1 was present on 94-99% of freshly isolated cells; this declined with culture (17-59%; P < 0.005) but was readily induced by IFN-gamma, IL-1 beta, and tumour necrosis factor-alpha. Alloreactivity and, presumably, autoreactivity to chondrocytes requires factors in addition to the surface expression of DR and ICAM-1. However the presence of these molecules suggests a capacity for cell-cell interactions in inflammatory sites such as the cartilage pannus junction.

Antigenic responses in reactive arthritis

In this article, the mechanisms by which infection at a distant site could lead to ReA and whether they could explain the association of ReA with HLA-B27 have been discussed. We propose that ReA synovitis is primarily due to specific synovial T-cell proliferation to fragments of the triggering bacterial found in the joint. Nonspecific T cells amplify synovitis with antibodies playing only a secondary role. First, we have shown that the triggering bacterial antigen is present in a nonviable form in ReA synovium and that this, not cross-reactive joint autoantigen, stimulates the specific synovial immune response. Second, the studies of the humoral immune response in ReA have been reviewed. Further evidence of bacterial persistence in the joint comes from work demonstrating intrasynovial bacteria-specific antibody synthesis. Continuing maturation of the antibody response also points to persisting antigen. In enteric but not genitourinary ReA, the humoral response is mainly IgA, implying chronic stimulation of the gut mucosa. Analysis of the molecules against which the humoral response is directed has shown no difference between yersinia arthritis and yersiniosis, but in CTA, the response to the 57kD and 59kD antigens differs from CT urethritis suggesting they may be arthritogenic. Finally, the antibody response may be absent in ReA patients rendering antibody titres diagnostically less useful and confirming their secondary role in the pathogenesis of synovitis. Third, studies of cellular response in ReA have been analyzed. We show there is a specific synovial MNC proliferative response to fragments of the triggering bacteria found in the joint, which is potentially of diagnostic use. The proliferation is due to CD4+ and CD8+ T cells and restricted by MHC class I and II antigens. This antigen-specific T-cell response is accompanied by an antigen-independent recruitment of nonspecific T cells, which may contribute to the amplification of synovitis. The importance of the synovial APC in determining the synovial immune response is unarguable but the exact mechanisms are unclear. Further details on the possible role of HLA-B27 in the presentation of arthritogenic peptides and on the exact identity of the antigenic epitopes recognized in ReA must await analysis of a large panel of T-cell clones. Finally, it is hoped that advances in this field will lead to specific and effective immunologic therapies or vaccines for this currently untreatable disease.

Serial estimation of interleukin 6 as a measure of systemic disease in rheumatoid arthritis

Disease activity in rheumatoid arthritis (RA) is frequently associated with a marked acute phase response, thrombocytosis, hypergammaglobulinemia and the presence of rheumatoid factors (RF). Interleukin 6 (IL-6) is a cytokine that stimulates hepatocytes to produce acute phase reactants and B lymphocytes to produce immunoglobulin. We measured serum IL-6 in patients with active RA during induction of intramuscular gold therapy. Levels of IL-6 correlated strongly with the erythrocyte sedimentation rate and RF titers and to a lesser degree with platelet counts. It may, therefore, be responsible for many of the systemic manifestations of RA and its measurement in the serum may be a convenient and reproducible variable for the assessment of disease activity in this very common disease.

The T-cell-receptor repertoire in the synovial fluid of a patient with rheumatoid arthritis is polyclonal

We have analyzed the T-cell-receptor repertoire expressed in the synovial fluid of a patient with rheumatoid arthritis by using an inverse polymerase chain reaction. Total RNA was isolated from Ficoll-purified mononuclear cells and converted into circularized double-stranded cDNA. Specific amplification of alpha- and beta-chain variable regions (V alpha and V beta) was achieved with inverted alpha- and beta-chain constant region (C alpha and C beta) primer pairs, and the amplification products were cloned into phage vectors. A total of 78 alpha and 76 beta clones were sequenced, and 67 and 72 productively rearranged alpha and beta genes were identified, respectively. Thirty-one V alpha, 33 alpha-chain joining region (J alpha), 29 V beta, and 12 beta-chain joining region (J beta) gene segments were found in the productively rearranged clones, indicating that the T-cell repertoire expressed in the synovial fluid of this RA patient is highly heterogenous and polyclonal. Comparison of peripheral blood and synovial fluid repertoires showed that the most abundant V beta sequences, V beta 2.1 and V beta 3.1, were enriched in the inflamed joint by a factor of 2 to 3. It is possible that T cells expressing these V beta gene segments, which recognize bacterial superantigens, play a role in the disease.

Immunotherapy of rheumatic diseases--practice and prospects

Present treatments for rheumatic diseases are both toxic to patients and largely ineffective in modifying the disease process. This report, based on a meeting recently held in London, investigates how far recent molecular and immunological advances can be converted into more effective, less toxic and, above all, more specific therapies.

The preferential accumulation of helper-inducer T lymphocytes in inflammatory lesions: evidence for regulation by selective endothelial and homotypic adhesion

The mechanisms which lead to the accumulation of T lymphocytes into inflammatory lesions are not clearly understood. We have previously shown that synovial CD4 T lymphocytes are mostly CDw29+UCHL1+ (helper-inducer cells) and very few carry the CD45R antigen which identifies the suppressor-inducer subset. Synovial CD8+ cells are also CDw29+UCHL1+CD45R-. In the present study, lymphocytes from pleural and peritoneal inflammatory infiltrates were shown to have a similar phenotypic pattern. Furthermore, it was demonstrated that the CDw29+UCHL1+ subset had a greater ability than CD45R+ cells to adhere to endothelial cells and to form homotypic clusters. Differential surface expression of LFA-1 on the two subsets was also shown, but this could not account for the demonstrated adhesion differences. Differences in adhesion between CDw29+/UCHL1+ and CD45R+ cells may explain the preferential accumulation of CDw29+/UCHL1+ cells in inflammatory infiltrates and underlie some of the functional differences between cells taken from sites of chronic inflammation and those from peripheral blood.

Abnormal distribution of the helper-inducer and suppressor-inducer T-lymphocyte subsets in the rheumatoid joint

T lymphocytes can be divided into two main phenotypic populations, CD4 and CD8. These can be further subdivided into 2H4, 4B4, or UCHL1 subsets by appropriate monoclonal antibodies. We have investigated these subsets in the synovial fluid of patients with rheumatoid arthritis and have found (i) a virtual absence of CD4+ 2H4+ and the marked reduction of CD8+ 2H4+ T cells; (ii) a marked increase of CD4+ 4B4+ and CD8+ 4B4+ T cells; and (iii) a marked increase of CD4+ UCHL1+ and CD8+ UCHL1+ T cells compared with peripheral blood. Although the functions of the CD8 subsets are not known, the virtual absence of CD4+ 2H4+ suppressor-inducer T cells and the marked increase of CD4+ 4B4+ helper-inducer T cells and of CD4+ UCHL1+ memory T cells may help to explain the many known functional immunological properties of synovial T cells.

Differential dosing study of pirazolac, a new non-steroidal anti-inflammatory agent, in patients with rheumatoid arthritis

Twenty-four patients with classical or definite rheumatoid arthritis participated in a 4-week double-blind crossover study to compare the effectiveness of two different dosage regimens of pirazolac. Patients were allocated at random to receive 2-weeks' treatment with either 300 mg pirazolac in the morning and 600 mg at night or 450 mg pirazolac given morning and evening, and were then crossed over to the alternative regimen for a further 2 weeks. Physician assessments of disease activity were carried out on entry and at the end of each treatment period, and patients kept a daily record of visual analogue scale scores for pain and stiffness. The results showed that both dosage regimens of pirazolac produced a significant improvement in the parameters assessed, but the difference between the two regimens was not significant. However, overall assessment at the end of the trial by the 23 patients who completed the study showed that 14 preferred the 300/600 mg regimen compared with 7 who preferred the 450/450 mg regimen: 2 patients considered both regimens equally effective. Pirazolac was relatively well tolerated, only a few patients reporting gastro-intestinal (2) and skin (3) side-effects during the trial period.

Mechanisms of depressed delayed-type hypersensitivity in rheumatoid arthritis: the role of protein energy malnutrition

The presence of anergy and its relationship to malnutrition was investigated in patients with rheumatoid arthritis (RA) and in controls. A generalised reduction in delayed cutaneous hypersensitivity to 7 recall antigens were found in 104 RA patients compared with 67 controls. No measured of the disease was capable of predicting cutaneous anergy, which was present in 36% of patients but none of the controls. A detailed dietary assessment in 30 RA patients and 30 controls revealed little evidence of clinically important malnutrition. It is therefore concluded that the cutaneous anergy of rheumatoid arthritis is not a consequence of nutritional factors.

HLA-B27 and the immune response to enterobacterial antigens in ankylosing spondylitis

Total serum immunoglobulins and class specific serum antibodies to Klebsiella pneumoniae, Salmonella typhimurium, Yersinia enterocolitica and Pseudomonas aeruginosa were measured in 107 patients with ankylosing spondylitis (AS) and 110 healthy tissue typed controls by enzyme linked immunosorbent assay (ELISA). The specificity of this technique was confirmed by the use of specific bacterial murine antisera and by cross-absorption of human sera by specific bacteria. Total serum IgA in AS patients correlated with both erythrocyte sedimentation rate (ESR) (P less than 0.001) and C-reactive protein (P less than 0.05) and was significantly elevated compared to healthy individuals (P less than 0.001). A significant elevation of IgA antibodies to K. pneumoniae was detected in the serum of AS patients with active disease when compared to healthy controls (P less than 0.01). These studies support the involvement of an enterobacterial micro-organism in the pathogenesis of AS and further relate to the role of HLA-B27 in this disease.

The involvement of interdigitating (antigen-presenting) cells in the pathogenesis of rheumatoid arthritis

Macrophage like cells expressing high concentrations of HLA-DR antigen have been identified in situ within the synovium of patients with rheumatoid arthritis. The characteristics of these cells have been determined using immunohistological analysis and combined cytochemical techniques. It was found that the majority (greater than 80%) of these cells were interspersed within the perivascular lymphocytic infiltrates occurring in the synovium. These cells did not stain with antisera against surface immunoglobulin or any Mc Abs to T lymphocyte markers. Further combined staining demonstrated that the HLA-DR + ve cells did stain with an anti-monocyte monoclonal (FMC-17), but could not be stained with a Mc Ab against C3b receptors. The interfacing of cytochemical reactions for acid phosphatase (ACP) and adenosine triphosphatase (ATPase) with immunofluorescence staining for HLA-DR demonstrated that these cells were ACP - ve ATPase + ve. This analysis led to the conclusion that the HLA-DR + ve cells found in abundance in the rheumatoid synovium expressed identical characteristics to the interdigitating cells of the normal lymph node paracortex. The possible significance of the presence of large numbers of such antigen presenting cells in the rheumatoid synovium is discussed.

T cell subset abnormalities in tissue lesions developing during autoimmune disorders, viral infection, and graft-vs.-host disease

The authors review a large body of contemporary immunohistologic findings on the tissue distribution of T lymphocytes in normal and pathological conditions. The suggestions for technological advances in this field are: signal amplification using mixtures of monoclonal antibodies directed against different epitopes on the same antigen (e.g. OKT4A+B+D), triple layer amplification systems using hapten-labelled antibodies, and informative double staining methods with combinations of antibodies labelled with different fluorochromes or enzymes. Review of histological observations in a series of human diseases suggests that imbalances of OKT4+ and OKT8+ subsets of T lymphocytes may represent different types of immunoregulatory disorders. Rheumatoid arthritis and sarcoidosis appear to involve a high level of OKT4+ subpopulation response coupled with an associated appearance of a special type of HLA-DR+ macrophages. It remains to be seen whether normal or self-limited immunological responses (early stages of bacterial infection or delayed-type hypersensitivity reactions) produce OKT4+ and macrophage responses that are characteristically different. Meanwhile, excessive levels of OKT8+ cells have been found in a wide range of recognized or presumed immunoregulatory disorders including: graft-vs.-host reaction and viral infections. These disorders, as well as primary biliary cirrhosis and lichen planus, appear to possess both overlapping and disparate clinical characteristics, and the immunohistological observations may reflect the functional heterogeneity of OKT8+ populations in these diseases. These studies show that histologically meaningful heterogeneity can already be demonstrated for the OKT8+ lymphocyte group.

Histochemical discrimination of HLA-DR positive cell populations in the normal and arthritic synovial lining

A combination of immunochemical staining for HLA-DR antigens and the histochemical demonstration of enzyme activity has been used to identify specific cell populations in the normal and arthritic synovial lining layers. Such combined staining has revealed that the normal synovial lining contains a proportion of HLA-DR + ve cells, all of which show strong lysosomal enzyme activity. This population is greatly expanded in biopsies from patients with osteoarthritis and these positive cells also express strong ATPase activity. In the rheumatoid synovium five distinct cell types can be identified; all of which are HLA-DR + ve but differ in their morphology and pattern of enzyme activity. Of special interest was the discovery that a small but significant proportion of these cells have the characteristics of the interdigitating cells of the lymph node paracortex. The relationship between the emergence of these heterogeneous populations and the immunological basis of this inflammatory response is discussed.

Rheumatoid arthritis: a disease of T-lymphocyte/macrophage immunoregulation

In rheumatoid arthritis the synovial membrane has many of the characteristics of a hyperactive, immunologically-stimulated lymphoid organ. The basis of this hyperactivity is poorly understood. Highly specific antisera to human Ia-like (HLA-DR) antigens and monoclonal antibodies (OKT series) to various T-lymphocyte subsets were used to analyse both the normal and the rheumatoid synovium and to compare it with normal lymph nodes. In rheumatoid arthritis the synovium acquires an infiltrate with microanatomical similarities to the paracortical area of the lymph node. Large, very strongly HLA-DR-positive macrophage-like interdigitating cells form close contacts with the OKT4+ (inducer-type) T-cells, while the OKT8+ population (T-cells of suppressor-cytotoxic type) between the macrophage-OKT4+ cell clusters is scanty (T4/T8 ratio = 9:1). By contrast, in the lymph node there are more OKT8 T-cells interspersed between the HLA-DR+ interdigitating cells and OKT4+ cells (T4/T8 ratio = 2:1). The large interdigitating cells and the OKT4+ T-cell population may be mutually stimulatory. In the absence of efficient suppression this stimulation may lead to activation of B-lymphocytes and oligoclonal or polyclonal immunoglobulin synthesis, as is found in the synovial membrane in rheumatoid arthritis.

Ankylosing spondylitis, HLA-B27 and Klebsiella. I. Cross-reactivity studies with rabbit antisera

Sera from rabbits immunized with HLA-B27 lymphocytes showed increased activity against klebsiellal enterobacter antigens using immunodiffusion, bacterial agglutination (P less than 0.025), haemagglutination (P less than 0.001) and radiobinding assays (P less than 0.001). Immunoprecipitin lines were also produced by these antilymphocyte sera against extracts from Yersinia enterocolitica and Shigella sonnci microorganisms. Rabbit anti-klebsiella sera had lymphocytotoxic activity against HLA-B27 lymphocytes obtained from patients with ankylosing spondylitis (P less than 0.001). These results suggest partial cross-reactivity between some antigens found in several Gram-negative microorganisms and HLA-B27 lymphocytes.

Cytology of rheumatoid synovial cells in culture. I. Composition and sequence of cell populations in cultures of rheumatoid synovial fluid

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