MHC class II associations with autoantibody and T cell immune responses to the scleroderma autoantigen topoisomerase I

Topoisomerase I (topo I) is a major autoantigen recognized by autoantibodies in about 30% of sera from patients with systemic sclerosis (SSc). Certain HLA-DRB1 and HLA-DQB1 alleles have been reported to be associated with autoantibody and T-cell responses to topo I suggesting a T-cell dependent process. We have examined the MHC class II allele associations with anti-topo I antibodies in 16 patients with SSc compared to 250 healthy controls. Furthermore, we have studied the T cell responses to a recombinant full-length topo I molecule purified from a baculovirus expression system in eight patients with SSc and eight controls (five healthy and three with autoimmune disease). HLA-DR5 was significantly increased in patients with anti-topo I antibodies (P< 0.02). Proliferative peripheral blood mononuclear cell (PBMC) responses to soluble topo I were present in nine of 16 individuals (four of eight with SSc and five of eight controls), including the three SSc patients with anti-topo I antibodies. Homozygosity for HLA DQB1:30:Y alleles was present in five of nine responders (P< 0.03) compared to none of the non-responders. Our findings support the notion that the MHC class II background influences the ability to generate an autoimmune response to intracellular autoantigens to which the immune system may not have been tolerized. Additional factors associated with the generation of autoantibodies appear to be more intimately associated with the development of SSc.

Class II MHC antigens in early rheumatoid arthritis in Bath (UK) and Madrid (Spain)

OBJECTIVE

A number of studies have indicated that rheumatoid arthritis (RA) is a less severe disease in Mediterranean countries than in Northern Europe. We investigated whether differences in the frequency of class II MHC antigens might contribute to this variation in disease severity.

METHODS

Typing at HLA-DR and -DQ loci was carried out at low and high resolutions by polymerase chain reaction amplification in patients with early RA of less than 6 months' duration (68 patients in Madrid and 68 in Bath) and in control subjects (929 in Madrid and 226 in Bath). Only ethnic Spanish and British individuals were included as patients and controls.

RESULTS

Shared epitope (SE) alleles represented 19.8 and 28.9% of the total number of class II MHC alleles in controls from Madrid and Bath respectively (P: = 0.00001), this difference being largely due to increased numbers of DRB1*0401 individuals in the British subjects (P: = 0.0000001). Analysis of the patients showed the expected increase in SE alleles when compared with their respective control groups (Madrid, 31.6 vs 19.8%; Bath, 42.6 vs 28. 9%). In Bath the SE was mainly encoded by HLA-DR4 alleles (74.1%), while in Madrid it was encoded almost equally by DR4 (51.1%) and DR1 (44.7%) alleles. The risk of developing RA in carriers of SE alleles was similar in the two cities (Bath, odds ratio 1.83, 95% confidence interval 1.23-2.78; Madrid, odds ratio 1.87, 95% confidence interval 1.25-2.77), and was largely accounted for by HLA-DRB1*0401 alleles.

CONCLUSION

We conclude that rheumatoid patients in Bath differ from their Spanish counterparts in class II antigen expression and allele frequency. This may be explained partly by genetic differences between the control populations in the two centres, and may help to explain the greater incidence of more severe rheumatoid disease expression seen in RA patients in the UK.

Lack of activation induced cell death in human T blasts despite CD95L up-regulation: protection from apoptosis by MEK signalling

The generation of effective immunity requires that antigen-specific T cells are activated, clonally expanded and ultimately eliminated by apoptosis. The involvement of CD95-mediated apoptosis in T-cell elimination is well established, but the conditions which regulate the death pathway under normal circumstances are still emerging. Using superantigen-activated human T cells, we found that whilst T-cell receptor (TCR) signalling triggered up-regulation of CD95 ligand (CD95L), the majority of T cells were resistant to apoptosis induction, despite co-expressing high levels of CD95. Resistance was maintained following direct antibody-mediated cross-linking of CD95 and was not confined to early time periods following activation. Our data implicate TCR-derived signals in protection from apoptosis and reveal a role for the mitogen-activated protein (MAP) kinase pathway by use of a MAP kinase kinase (MEK) inhibitor. Collectively these data demonstrate that resistance to activation-induced cell death in human T cells is prolonged rather than transient, is not attributable to a lack of CD95L up-regulation and is due, at least in part, to signalling via the MEK pathway.

Down-regulation of CD28 via Fas (CD95): influence of CD28 on T-cell apoptosis

Following antigen engagement of the T-cell receptor (TCR), T-cell survival is largely dictated by the provision of additional signals, such as those from costimulatory receptors and cytokine receptors. Whilst CD28-mediated signalling is increasingly associated with survival, ligation of alternative T-cell antigens, such as Fas (CD95), can trigger apoptosis. The T-cell response following antigen engagement may therefore be influenced by the relative expression levels of these coreceptors as well as by the availability of their ligands (CD80/86 and Fas-L). In this study we demonstrate functional interplay between the death receptor Fas and the costimulatory receptor CD28 in human T cells. In Jurkat T cells, we show that Fas signalling leads to rapid and selective CD28 down-regulation, and that this is associated with a specific decrease in mRNA for CD28, indicating that mechanisms exist which target CD28 at a transcriptional level. Moreover, cells that down-regulate CD28 also undergo apoptosis. Studies on activated human peripheral blood T cells demonstrate that cells expressing high levels of CD28 are resistant to Fas-mediated apoptosis whereas cells expressing low levels are more susceptible, implicating CD28 in the provision of anti-apoptotic signals. Consistent with this hypothesis, direct ligation of CD28 using B7 transfectants concomitant with anti-Fas challenge protects from apoptosis. Since antigen-presenting cells may express Fas-L under certain circumstances, the maintenance of T-cell CD28 expression may be crucial for the prevention of Fas-mediated apoptosis during the course of antigen engagement.

Expression of the cutaneous lymphocyte antigen and its counter-receptor E-selectin in the skin and joints of patients with psoriatic arthritis

We have investigated whether the skin-homing T lymphocytes identified by the cutaneous lymphocyte antigen (CLA) are increased in the synovial membrane of patients with psoriatic arthritis. Twenty-six synovial samples (13 psoriatic arthritis, seven rheumatoid arthritis, six osteoarthritis) were obtained from involved knees. Lesional skin biopsies were taken from nine of the patients with psoriatic arthritis and six patients with psoriasis alone. All samples were single- and dual-stained for CLA and CD3 (to identify T lymphocytes) using HECA-452 (anti-CLA) and anti-CD3 monoclonal antibodies. E-selectin expression was also determined. The percentage of dual-stained lymphocytes was significantly greater in psoriatic skin than in synovium (P < 0.001) and similar between psoriatic and rheumatoid synovium. There was no significant difference in the percentages of CLA-positive cells in psoriatic skin in patients with psoriatic arthritis compared with psoriasis alone. The intensity of endothelial E-selectin expression was significantly greater in skin psoriasis than in synovium (P < 2 x 10(-5)), and rheumatoid synovium had significantly greater expression than psoriatic synovium (P < 0.05). However, there was no significant correlation between E-selectin expression and the percentages of CLA-positive lymphocytes. This study provides further evidence that the CLA antigen is enriched on skin-homing lymphocytes. Conversely, the link between skin and joint inflammation in psoriatic arthritis does not seem to be explained by increased trafficking of CLA T cells to psoriatic synovium.

Modulation of cytokine production by human mononuclear cells following impairment of Na, K-ATPase activity

Cytokines, including TNF alpha and IL-l beta, are central to the chronic inflammatory process and tissue damage that characterises diseases such as rheumatoid arthritis. The mechanisms responsible for long-term generation of these molecules are poorly understood. We have previously demonstrated impaired activity of Na, K-ATPase, a key enzyme regulating intracellular cation levels, on rheumatoid mononuclear cells. Mimicking this 'defect' on normal mononuclear cells with ouabain has been shown to induce TNF alpha and, in particular, IL-l beta production, whereas IL-6 synthesis was suppressed. A similar pattern of cytokine generation was noted when mononuclear cells were treated with the sodium ionophore, monensin. Induction of cytokine production was related to up-regulation of the appropriate mRNA, although enhanced secretion of processed IL-l beta was also observed. The mechanism underlying these cellular responses appears to involve sodium/calcium exchange across the cell membrane. Impaired Na,K-ATPase activity might promote pro-inflammatory cytokine secretion in patients with rheumatoid arthritis.

Quantitation of IL-2Rp75 (CD122) expression on mononuclear cells in rheumatic disease

OBJECTIVE

To compare expression of the p75 chain of the interleukin-2 receptor (IL-2Rp75, CD122) on peripheral and synovial mononuclear cells in rheumatoid and non-rheumatoid inflammatory arthritis.

METHODS

Peripheral blood (PBMC) and synovial (SFMC) mononuclear cells were isolated from subjects with rheumatoid arthritis (n = 16) and non-rheumatoid inflammatory arthritis (n = 12). PBMC were isolated from six healthy controls. Expression of CD122 was examined using indirect immunofluorescence and quantitative flow cytometry.

RESULTS

There was no difference in IL-2Rp75 expression on PBMC from rheumatoid arthritis patients, non-rheumatoid arthritis patients, and controls. In subjects with rheumatoid arthritis there was no difference in IL-2Rp75 expression on PBMC and SFMC. However, in the non-rheumatoid arthritis group there was an increase in IL-2Rp75 expression on SFMC compared with PBMC (P = 0.0032). On SFMC there was a greater expression of IL-2Rp75 in non-rheumatoid arthritis than in rheumatoid arthritis (P = 0.0007). Expression was greater on CD8 positive cells and in subjects with shorter duration of disease.

CONCLUSIONS

The p75 chain of the IL-2 receptor, an important T cell activation antigen, is not upregulated in synovial fluid. This appears to be a disease specific defect and provides further support for the concept of "frustrated" or incomplete T cell activation in this disease.

Induction of activator protein (AP)-1 and nuclear factor-kappaB by CD28 stimulation involves both phosphatidylinositol 3-kinase and acidic sphingomyelinase signals

A major obstacle in understanding the signaling events that follow CD28 receptor ligation arises from the fact that CD28 acts as a costimulus to TCR engagement, making it difficult to assess the relative contribution of CD28 signals as distinct from those of the TCR. To overcome this problem, we have exploited the observation that activated human T cell blasts can be stimulated via the CD28 surface molecule in the absence of antigenic challenge; thus, we have been able to observe the response of normal T cells to CD28 activation in isolation. Using this system, we observed that CD28 stimulation by B7-transfected CHO cells induced a proliferative response in T cells that was not accompanied by measurable IL-2 production. However, subsequent analysis of transcription factor generation revealed that B7 stimulation induced both activator protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB) complexes, but not NF-AT. In contrast, engagement of the TCR by class II MHC/superantigen, either with or without CD28 ligation, resulted in the induction of NF-AT, AP-1, and NF-kappaB as well as IL-2 production. Using selective inhibitors, we investigated the signaling pathways involved in the CD28-mediated induction of AP-1 and NF-kappaB. This revealed that NF-kappaB generation was sensitive to chloroquine, an inhibitor of acidic sphingomyelinase, but not to the phosphatidylinositol 3-kinase inhibitor, wortmannin. In contrast, AP-1 generation was inhibited by wortmannin and was also variably sensitive to chloroquine. These data suggest that in activated normal T cells, CD28-derived signals can stimulate proliferation at least in part via NF-kappaB and AP-1 generation, and that this response uses both acidic sphingomyelinase and phosphatidylinositol 3-kinase-linked pathways.

Induction of activator protein (AP)-1 and nuclear factor-kappaB by CD28 stimulation involves both phosphatidylinositol 3-kinase and acidic sphingomyelinase signals

A major obstacle in understanding the signaling events that follow CD28 receptor ligation arises from the fact that CD28 acts as a costimulus to TCR engagement, making it difficult to assess the relative contribution of CD28 signals as distinct from those of the TCR. To overcome this problem, we have exploited the observation that activated human T cell blasts can be stimulated via the CD28 surface molecule in the absence of antigenic challenge; thus, we have been able to observe the response of normal T cells to CD28 activation in isolation. Using this system, we observed that CD28 stimulation by B7-transfected CHO cells induced a proliferative response in T cells that was not accompanied by measurable IL-2 production. However, subsequent analysis of transcription factor generation revealed that B7 stimulation induced both activator protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB) complexes, but not NF-AT. In contrast, engagement of the TCR by class II MHC/superantigen, either with or without CD28 ligation, resulted in the induction of NF-AT, AP-1, and NF-kappaB as well as IL-2 production. Using selective inhibitors, we investigated the signaling pathways involved in the CD28-mediated induction of AP-1 and NF-kappaB. This revealed that NF-kappaB generation was sensitive to chloroquine, an inhibitor of acidic sphingomyelinase, but not to the phosphatidylinositol 3-kinase inhibitor, wortmannin. In contrast, AP-1 generation was inhibited by wortmannin and was also variably sensitive to chloroquine. These data suggest that in activated normal T cells, CD28-derived signals can stimulate proliferation at least in part via NF-kappaB and AP-1 generation, and that this response uses both acidic sphingomyelinase and phosphatidylinositol 3-kinase-linked pathways.

Differential expression of the costimulatory molecules B7.1 (CD80) and B7.2 (CD86) in rheumatoid synovial tissue

CD4+ T-lymphocytes require two signals to become activated--antigen receptor (TcR) occupancy and an antigen-presenting cell (APC)-derived costimulus. The latter may be provided by B7.1 (CD80) or B7.2 (CD86) on APC interacting with CD28 on T-cells. We have studied the expression of these costimulatory molecules in rheumatoid and osteoarthritic synovial membrane. Very few B7.1-positive cells were seen in synovial tissue from either established or early rheumatoid disease, or in rheumatoid arthritis (RA) or osteoarthritis (OA) synovia at arthroplasty. In contrast, B7.2 was readily detected in rheumatoid synovia, predominantly in the lining layer, in a pattern of expression that corresponded to the presence of CD68-positive macrophages. Only occasional B7.2-positive cells were seen in OA synovia. The presence of B7.2 but the relative lack of expression of B7.1 may be partly responsible for the observations of 'frustrated' T-cell activation or T-cell hyporesponsiveness in the rheumatoid synovium.

Detection of anti-topoisomerase I antibodies using a full length human topoisomerase I recombinant protein purified from a baculovirus expression system

Topoisomerase I (topo I) is a major systemic sclerosis (SSc)-associated autoantigen. A cDNA construct encoding full length human topo I in a recombinant baculovirus transfer vector was used to infect insect cells in culture from which recombinant protein was purified. An ELISA using recombinant protein was evaluated in 340 sera including sera from 134 patients with SSc, of whom 33 had anti-topo I antibodies detected by immunodiffusion. A high yield of pure topo I of expected molecular mass and catalytic activity was obtained. The recombinant topo I ELISA was 92% sensitive and 98% specific in detecting anti-topo I antibodies which were present almost exclusively in patients with SSc. Therefore, the potential advantages of expressing human autoantigens in eukaryotic systems for diagnostic purposes were confirmed.

Elevated serum interleukin-6 levels associated with active disease in systemic connective tissue disorders

OBJECTIVE

It is well established that connective tissue diseases such as systemic lupus erythematosus (SLE) are associated with a weak or absent acute phase response, although elevated serum interleukin 6 levels have been described. In this study, we have sought to correlate serum levels of IL-6 with standard laboratory and clinical assessments of disease activity in two connective tissue diseases, namely SLE and systemic sclerosis (SSc), and, for comparative purposes, rheumatoid arthritis (RA).

METHODS

Serum IL-6 levels were determined by bioassay and also, in some sera, by immunoradiometric assay. They were compared with two inflammatory parameters, serum C-reactive protein (CRP) and plasma viscosity (PV), and with appropriate clinical measurements in the various patient groups, including BILAG in SLE, the skin score in SSc, and the Ritchie index in RA.

RESULTS

Serum IL-6 (SeIL-6) levels were elevated in active SLE, SSc, and RA. This was poorly correlated with the acute phase response in SLE and SSc, but there was a strong relationship of SeIL-6 to disease activity in these conditions. In SLE, the BILAG disease activity index correlated best with SeIL-6 levels while there was only a weak relationship between CRP and IL-6, and no relationship between CRP and disease activity. In SSc there was a relationship of disease activity to SeIL-6 but not between SeIL-6 and either CRP or PV. In a small RA group there was a much stronger relationship of SeIL-6 to CRP and PV, as has been previously described.

CONCLUSION

The determination of SeIL-6 may be a useful indicator of disease activity in those patients groups, including SLE and SSc, in which a normal acute phase response by the liver is often lacking. The mechanism underlying this hepatic impairment requires further investigation, but is clearly not due to a failure to generate the appropriate cytokine signal. Excessive local or systemic production of IL-6 in connective tissue diseases could play an important pathogenic role in these conditions, for example through stimulating autoantibody synthesis.

Ligation of CD28 receptor by B7 induces formation of D-3 phosphoinositides in T lymphocytes independently of T cell receptor/CD3 activation

The co-stimulatory role of B7/CD28 interactions is important in promoting T cell activation. Very little is known about the intracellular events that follow CD28 engagement although recent evidence has implicated coupling of CD28 to a protein tyrosine kinase signal transduction pathway. In this study we have investigated the putative role of D-3 phosphoinositides as mediators of CD28 receptor signaling, since phosphoinositide (PI) 3-kinase, the enzyme responsible for D-3 phosphoinositide formation, is a known substrate for protein tyrosine kinases associated with certain T cell surface receptors such as CD4 and interleukin-2 receptor. The lipid products of PI 3-kinase activity have been suggested to play a role in mitogenic signaling and growth regulation in other cells. Chinese hamster ovary cells (CHO) previously transfected with B7 cDNA, induced time-dependent elevation above basal levels of phosphatidylinositol(3,4)-bisphosphate (PtdIns(3,4)P2) and PtdIns(3,4,5)P3, while parental CHO cells that did not express B7 had no effect on these lipids. Moreover, the elevation of these same lipids by CD3 ligation was potentiated in an additive manner by CHO-B7+ but not by CHO-B7- cells. CHO-B7+ and CHO-B7- cells did not activate phospholipase C as evidenced by their inability to modulate basal or CD3-induced changes in the levels of phosphatidic acid or D-4 and D-5 phosphoinositides. These data imply that PI 3-kinase but not phospholipase C, may be an important signal transduction molecule with respect to CD28-mediated co-stimulation and T cell activation following ligation by B7.

B7/CD28 but not LFA-3/CD2 interactions can provide 'third-party' co-stimulation for human T-cell activation

The requirement for co-stimulation in T-cell activation has become firmly established, whilst the precise identity of the molecules involved remains uncertain. Some of the major co-stimulatory molecules include ICAM-1, LFA-3 and B7. We have investigated the abilities of both LFA-3 and B7 to co-stimulate T-cell proliferation under a number of conditions using transfected Chinese hamster ovary cells. Using anti-CD3 antibodies we observed that B7 but not LFA-3 transfectants were capable of co-stimulating proliferation in purified peripheral blood T cells. In addition, both LFA-3 and B7 could induce proliferation in response to phytohaemagglutinin (PHA) and we obtained additive effects using both B7 and LFA-3 together. Using the superantigen staphylococcal enterotoxin B (SEB), we observed that presentation to purified T cells required the presence of class II-positive transfectants and that sensitivity to antigen was increased approximately 100-fold by the co-transfection of either B7 or LFA-3. However, when co-stimulatory molecules were provided by cells separate from those engaging the T-cell receptor (TcR), only B7 was capable of enhancing proliferation. Kinetic studies which investigated the time dependence for co-stimulation revealed that T cells responding to anti-CD3 antibodies required the B7 co-stimulation within the first few hours, for proliferation to be effective. Our data differentiate between the co-stimulatory abilities of B7 and LFA-3 and support the concept of a pivotal role for B7 in T-cell proliferation.

Suppressive effects of a novel antioxidant compound on human T cell functions in vitro

The use of antioxidant compounds with differing modes of action has clearly demonstrated involvement of oxidative processes in the activation of T lymphocytes. In this paper, we show that a novel antioxidant (lazaroid U75412E, a free radical scavenger) suppressed mitogen-induced T cell proliferation in vitro. Similar results were obtained with diphenylene iodonium (DPI), a known inhibitor of NADPH oxidase. The lazaroid was further shown to inhibit IL 2 production but to be less potent in suppressing IL 2 receptor expression. Thus, scavenger-type antioxidants act on T cells primarily by blocking a signal necessary for the induction of IL 2 synthesis such as the activation of NF kappa B. Furthermore, the potent inhibition of lymphocyte responses caused by the specific enzyme inhibitor DPI provides direct proof of the source of the oxidants involved in these processes.

Impaired activity of thiol-dependent ATPases in rheumatoid mononuclear cell membranes

Ion-motive ATPase play an essential role in many aspects of cell biology, including mononuclear cell (MNC) functions relevant to chronic inflammation. For example, ouabain, a specific inhibitor of Na+, K+ ATPase, suppresses both T and B cell proliferation but induces synthesis of IL-1. Using a cytochemical assay quantified by microdensitometry, total and ouabain-sensitive ATPase activities have been compared in MNC from rheumatoid and control subjects. The sensitivity of these enzymes to inactivation by thiol-blocking reagents has been studied by preincubation with an impermeant SH blocker p-hydroxymercuriphenylsulphonate (pHMPSA). The results show that rheumatoid MNC have significantly impaired ATPase activity compared to healthy cells and that both total and ouabain-sensitive ATPase activities are readily inhibited by pHMPSA. The depressed ATPase activity in rheumatoid MNC could thus be due to blockade/oxidation of a reactive surface thiol, and could contribute to perpetuation of the chronic inflammatory process in these patients.

B7/BB1, the ligand for CD28, is expressed on repeatedly activated human T cells in vitro

The activation of T cells is now thought to require at least two distinct signals. One signal is delivered through the interaction of the antigen-specific T cell receptor with major histocompatibility complex (MHC) molecules and peptide, while the other is received from interactions with less precisely defined accessory or costimulatory molecules. In the absence of this second costimulatory signal, some T cells subsequently become unresponsive to antigenic stimulation. One of the major candidates for providing such a second signal to T cells is the molecule B7 interacting with the T cell glycoprotein CD28. In the present study we have investigated whether B7 is expressed on human T cell lines and clones, since these cells have the capacity to present antigen to each other by expressing MHC class II molecules. Our results demonstrate that B7 can be detected on T cell clones and on repeatedly activated but not freshly isolated peripheral blood T cells. The expression of B7 is dependent on the state of activation of the cells, being maximally expressed shortly after restimulation and becoming undetectable as the cells quiesce. Together, these results suggest that B7 expression may be of importance to T cells, perhaps in the avoidance of anergy.

Rhythms in the immune system

This report reviews the evidence that cells within the immune system are subject to rhythmic influences that affect numbers of circulating cells and their function both in vitro and in vivo. It is concluded that, although periodicity has clearly been demonstrated for numbers of immunocompetent cells in the circulation, significant functional changes have not been consistently observed. A number of neuroendocrine hormones, which modulate immune responsiveness in vitro and which are released in a rhythmic manner, are considered as mediators of the observed effects on the immune system and this is related to changes in expression and activity of immune-mediated diseases such as rheumatoid arthritis.

Autoantibodies to lipocortin-1 are associated with impaired glucocorticoid responsiveness in rheumatoid arthritis

Autoantibodies to the antiinflammatory protein lipocortin-1 have been found in patients with rheumatoid arthritis (RA) receiving oral glucocorticoids. The highest antibody titers correlated with a requirement for high maintenance doses of steroid (> 7.5 mg/day prednisolone). Forty-two patients with RA were grouped according to high or low autoantibody titer. In 18 patients, peripheral blood leukocyte counts and phenotypic analysis were performed before and 4 h after a single intravenous (iv) dose of 100 mg hydrocortisone. The group with low titer antibody exhibited a normal poststeroid peripheral blood lymphopenia, but the response in the group with high antibody titer was considerably blunted. In a 2nd study, 24 patients received 3 separate doses of 1000 mg iv methylprednisolone. After 8 weeks the group with the high titer antibody had shown no improvements in clinical or laboratory variables observed in the group with low titer antibody. Thus, the presence of high titer antilipocortin-1 antibody is associated with impaired responses to glucocorticoid therapy both in terms of clinical efficacy and effects on the immune system. This could explain the relative glucocorticoid resistance reported in a proportion of patients with RA.

Impaired suppressor cell activity due to surface sulphydryl oxidation in rheumatoid arthritis

Rheumatoid arthritis is a chronic inflammatory disorder with considerable evidence of impaired regulation of the immune response, including defective suppressor cell function, especially in the synovial membrane. We have investigated whether oxidation of cell surface thiols might be responsible for these defects and whether such cell function may be modulated towards normal by treatment with a sulphydryl-reactive drug, D-penicillamine. Using healthy mononuclear cells treated with an impermeant thiol blocker, induction of suppressor activity by incubation with the lectin Con A was not dependent on surface sulphydryl groups but suppressor activity was abolished by thiol blockade after Con A stimulation. Peripheral blood mononuclear cells from patients with active rheumatoid disease showed impaired Con A-induced suppressor activity which was enhanced to near-normal levels by incubating the rheumatoid cells with a sulphydryl reducing agent, 2-mercaptoethanol, or D-penicillamine. Con A-stimulation of cells from patients treated with intramuscular gold or D-penicillamine generated more active suppression than those from patients receiving non-steroidal drugs only. Mononuclear cells from patients with other chronic inflammatory joint diseases showed normal Con A-induced suppressor activity. These data support the conclusion that surface thiols on mononuclear cells in rheumatoid arthritis are reversibly oxidized by the disease process. This gives rise to aberrant cell function including impaired suppressor activity. Such a mechanism may be at least partly responsible for the defective immunoregulation seen in rheumatoid patients and thus be a relevant target for thiol containing antirheumatic drugs.

Modulation of human T cell functions by surface sulphydryl groups: differential effects on IL-2 production and responsiveness

An impermeable thiol blocker has been used to investigate the role of sulphydryl (SH) groups in the production of and responsiveness to IL-2 by normal human T lymphocytes. Surface SH blockade of mononuclear cells prior to incubation with mitogen (phytohaemagglutinin, concanavalin A, CD3 MoAb) had no effect on production of IL-2 but markedly impaired cellular responsiveness to exogenous IL-2. Studies using MoAbs indicated that this effect was accompanied by decreased expression of both the CD25 and p75 subunits of the IL-2 receptor. Blocking surface SH groups did not affect binding of IL-2 to p75 on unstimulated mononuclear cells, but inhibited binding to high-affinity receptors on a T lymphoma cell line. The data are consistent with the hypothesis that sulphydryl groups on the IL-2 receptor are required for its function and may be involved in the interaction of the CD25 and p75 subunits leading to generation of the high-affinity binding site. The surface thiol identified on the IL-2 receptor may be a candidate for oxidation on cells from patients with chronic inflammatory diseases such as rheumatoid arthritis and thus contribute to the aberrant function of T cells in these patients.

Predictors of the long-term outcome of early synovitis: a 5-year follow-up study

One hundred patients who presented to an Early Synovitis Clinic in 1979-81 were called for review after a minimum of 5 years. Sufficient data for analysis were obtained in 88 cases, of whom 36 had a final diagnosis of rheumatoid arthritis (19 seropositive, 17 seronegative) and 16 human parvovirus B19 arthropathy. Outcome was assessed by persistence of symptoms greater than 24 months and functional disability by Health Assessment Questionnaire. Sixty-two patients had persistent disease, with 26 showing some functional impairment (positive HAQ FDI). A number of presenting features were assessed for their ability to predict outcome at 5 years. Polyarticular onset of disease was associated with a poor prognosis but lacked both specificity and sensitivity. Certain laboratory tests at presentation, including positive rheumatoid factor and low serum sulphydryl levels, also indicated a poor outcome. Combining these serological abnormalities gave 100% specificity for detecting persistent, disabling disease but with rather low sensitivity. Thus, other test systems are required to increase further the successful prediction of clinical outcome in patients with early synovitis.

Radiological progression in rheumatoid arthritis: do D-penicillamine and hydroxychloroquine have different effects?

We studied 43 patients with active rheumatoid disease of less than 4 years' duration: 23 were given hydroxychloroquine and 20 penicillamine. Efficacy was assessed using clinical and laboratory variables. Radiological progression was measured using Larsen's method for scoring plain radiographs of the hands and feet. Twenty-four patients received 2 years' continuous therapy. Clinically both drugs were effective with falls in articular index and C-reactive protein. Initial radiological damage was less with penicillamine (P less than 0.05 by Wilcoxon rank sum test). By 2 years there were no significant differences between the two drugs; mean increases in Larsen score were 20.3 with penicillamine and 27.5 with hydroxychloroquine. Both groups progressed at a rate likely to give severe joint destruction over 10-20 years.

Factor VIII related antigen in connective tissue disease patients and relatives

This study assayed serum levels of FVIII Rag as a marker of endothelial injury in patients not only with frank connective tissue disease but also in those presenting with Raynaud's phenomenon and in families of those with systemic sclerosis. Elevated levels of FVIII Rag were found in 62% of patients with systemic sclerosis (SS), 38% with systemic lupus erythematosus (SLE), 67% with mixed connective tissue disease (MCTD) and in 17% with primary Raynaud's phenomenon. Twenty per cent of first degree relatives of patients with SS also demonstrated high levels of FVIII Rag and certain antibodies, namely those reacting with U1RNP and the centromere. The association between elevated FVIII Rag and antibodies linked to Raynaud's and vasculitis lends support to antibody involvement in pathogenesis. High levels of FVIII Rag in family members may reflect an increased susceptibility of endothelium to injury particularly since relatives also have a higher frequency of clinical features such as Raynaud's phenomenon.

HLA-DO-related restriction fragment length polymorphisms in rheumatoid arthritis: evidence for a link with disease expression

Eighty-three patients with rheumatoid arthritis (RA) were investigated for HLA-DQ and DR locus restriction fragment length polymorphisms (RFLP). Of the 83 patients, 61 (73%) possessed the DR4 allele and within this group we have investigated the relative frequencies of two DQ beta gene variants of DQw3, DQw7 and DQw8, one of which we had previously found to be raised in Felty's syndrome. This analysis revealed a significantly higher frequency of DQw7 containing haplotypes in DR4 positive rheumatoid patients (64%) than in DR-matched healthy controls (42%). Furthermore, the distribution of DQw7 was biased towards those patients with greater disability indicated by the HAQ score, more systemic disease and higher titres of rheumatoid factor, suggesting that DQw7 may contribute to disease expression.

Autoantibodies to recombinant lipocortin-1 in rheumatoid arthritis and systemic lupus erythematosus

Corticosteroids may mediate some of their anti-inflammatory effects via induction of a specific 38 kD protein, lipocortin-1. Autoantibodies to lipocortin-1 were measured by enzyme linked immunosorbent assay (ELISA) in 90 healthy subjects and in 63 patients with rheumatoid arthritis (RA), 36 with systemic lupus erythematosus (SLE), 26 with polymyalgia rheumatica, and 13 with chronic airways disease. Sixteen patients with RA receiving prolonged, high steroid doses (prednisolone greater than 7.5 mg/day) had raised IgM antilipocortin-1 levels, while 19 patients with RA untreated with steroids had normal levels. This association was independent of disease activity. In SLE, raised antilipocortin-1 levels were associated with active disease and were independent of steroid treatment. Antilipocortin-1 antibody levels were not raised in patients with polymyalgia rheumatica and chronic airways disease. Thus steroid treatment alone appears insufficient to induce antilipocortin-1 antibodies, unless an underlying autoimmune state is also present. In RA, antilipocortin-1 antibodies may impair anti-inflammatory actions of steroids and render some patients 'steroid resistant'.

Thymopentin (TP-5) in the treatment of rheumatoid arthritis

A randomized control trial of TP-5 in rheumatoid arthritis is reported. In a multicentre study, 76 patients were treated with TP-5 50 mg or placebo three times a week for 3 weeks as a slow intravenous injection, and followed for 7 weeks. Clinical parameters such as the Ritchie index and sum score of swollen joints improved significantly on TP-5 compared to placebo. Laboratory parameters did not change but an increased skin test score to common recall antigens was observed. Toxicity was minimal. TP-5 is a potentially useful agent in the treatment of rheumatoid arthritis, although further studies are required to determine the optimal treatment regimen.

The generation of lipid peroxides by stimulated human neutrophils. Detection using phenol red oxidation

When activated, phagocytic cells undergo a burst of oxidative metabolism, consuming oxygen and converting it to several products including superoxide anion and hydrogen peroxide. The latter may be quantified using an assay based on the oxidation of phenol red catalysed by horseradish peroxidase. This method has been employed to evaluate peroxide formation by human neutrophils activated in vitro with a variety of stimuli. Evidence is presented to show that neutrophils secrete different major peroxides depending upon the stimulus, its concentration and the incubation time. Based on inhibition studies using enzymes and drugs these may be identified as hydrogen peroxide and a lipoxygenase product, probably 5-hydroperoxyeicosatetraenoic acid (5-HPETE). Thus, phenol red oxidation may, under certain circumstances, represent a simple assay of lipoxygenase activity in stimulated human neutrophils.

Enhanced oxidative metabolism of neutrophils from patients with systemic sclerosis

Pathological features of systemic sclerosis (SS) such as endothelial cell injury may be associated with damage caused by active oxygen species, especially peroxides. Neutrophils from SS patients express more Fc(IgG) receptors and generate significantly more peroxide than control cells when cultured alone or with heat-aggregated IgG, but not with F-Met-Leu-Phe. We suggest that circulating neutrophils are activated in SS and may, through secretion of toxic peroxides, contribute to the early vascular pathology of this disease.

Lymphocytes bearing Fc gamma receptors in rheumatoid arthritis. IV. Increased numbers and activation of Facb-R+ cells after immunisation of healthy individuals

Mononuclear cells expressing Fc gamma receptors that form Facb rosettes are increased in the peripheral blood of patients with rheumatoid arthritis compared with controls. Healthy individuals with a positive skin response to tuberculin showed a marked increase in numbers of circulating Facb-R+ cells three days after challenge, returning to baseline after seven days. No response was observed in subjects showing a negative skin test. A similar increase in Facb-R+ cell numbers was measured after intramuscular injection of another specific antigen, tetanus toxoid. In addition to this enhancement of Facb-R+ cell numbers, evidence has been obtained that these cells are in an activated state postimmunisation as judged by acquisition of low density and increased expression of class II MHC antigens. Apparently identical changes in Facb-R+ cell numbers and activation may be induced in vitro either by culturing sensitised mononuclear cells with specific antigen for three days or by an overnight incubation of normal cells with gamma-interferon (gamma-IFN). By analogy, therefore, the increased numbers of Facb-R+ cells in patients with rheumatoid arthritis are probably induced by gamma-interferon generated as part of an antigen driven immune response. In this context it is interesting that patients with Felty's syndrome, in whom neutropenia increases susceptibility to infections leading to the possibility of further stimulation of the immune system by micro-organisms, have particularly high levels of circulating Facb-R+ cells.

Clinical and laboratory effects of nifedipine in Raynaud's phenomenon

The calcium channel blocking drug nifedipine was shown to be more effective than placebo as a treatment for Raynaud's phenomenon. Given in a dose of 10 mg four times a day it was well tolerated and reduced both the frequency and the severity of vasospastic attacks. There was, however, a large individual variation in response and while approximately half the patients showed marked improvement others showed no improvement at all. Patients with idiopathic Raynaud's phenomenon responded more favourably than those with systemic sclerosis. Nifedipine was shown to inhibit mitogen-induced lymphocyte proliferation but only in patients who responded to the drug clinically. Calcium channel blocking drugs may therefore have potential as immunoregulatory agents.

Lymphocytes bearing Fc gamma receptors in rheumatoid arthritis. III. Immunoregulatory function associated with Facb rosette-forming cells

A subpopulation of mononuclear cells (PBMNC) that expresses Fc receptors with specificity for the C gamma 2 region of IgG may be detected by rosette formation with calf erythrocytes coated with the Facb fragment of rabbit IgG. These Facb-R+ cells are found in increased numbers in the peripheral blood of patients with rheumatoid arthritis (RA). Studies have been carried out to identify the functional properties of these cells in healthy and rheumatoid subjects. Facb-R+ cells were shown to lack both natural killer and antibody-dependent cytotoxic activity. Depletion of Facb-R+ cells from both healthy and rheumatoid PBMNC resulted in a marked suppression of pokeweed mitogen (PWM) stimulated IgG synthesis but had no effect on T cell proliferation induced by phytohaemagglutinin, concanavalin A, or PWM. The addition of Facb fragments to PBMNC cultures also caused inhibition of PWM-driven IgG production. In this assay rheumatoid PBMNC were significantly less sensitive to Facb-mediated suppression than healthy control cells. Our results suggest that Facb-R+ cells are involved in the antibody-mediated feedback regulation of immunoglobulin synthesis and that this mechanism is impaired in patients with RA.

Lymphocytes bearing Fc gamma receptors in rheumatoid arthritis. II. Phenotypic characterisation of mononuclear cells forming Facb rosettes in RA

We have previously reported an increased proportion of Facb-rosette forming cells in the peripheral blood of patients with rheumatoid arthritis in comparison with healthy controls. The present study investigates the surface phenotype of these cells by means of monoclonal antibodies and a variety of rosetting and lymphocyte fractionation techniques. Facb-R+ cells were found to lack surface markers characteristic of T and B lymphocytes. Studies with monoclonal reagents showed a positive reaction with OKIa1, OKM1, and another monocyte-specific antibody. Fac-R+ cells were recognised by anti-HLA-DR reagents but did not bind the monoclonal antibody 17.15 that recognises a determinant on HLA-DR antigens expressed by lymphocytes but not monocytes. These results show that Facb-R+ cells share certain surface characteristics with monocytes, though they are not phagocytic. These observations are consistent with an accessory role for Facb-R+ cells in the immune response.

Defective monocyte accessory function due to surface sulphydryl (SH) oxidation in rheumatoid arthritis

Low serum sulphydryl (SH) levels are a feature of active rheumatoid arthritis (RA). We have investigated whether a similar blockade of membrane SH groups on mononuclear cells modifies the function of these cells in this disease. Using pokeweed mitogen stimulated IgG synthesis as the assay system, we have found that the accessory cell function of peripheral blood monocytes is totally dependent on free SH groups on the cell surface. Monocytes from patients with active RA display poor accessory cell function when compared with healthy monocytes or with cells from patients treated with D-penicillamine. The poor function of the rheumatoid accessory cells may be corrected in vitro by 2-mercaptoethanol (2-ME). Addition of 2-ME to the culture system also enhances IgG synthesis by rheumatoid mononuclear cells to normal levels. We suggest that surface SH-dependent mechanisms are responsible, at least in part, for the depressed mononuclear cell functions of rheumatoid cells in vitro and may explain some effects of D-penicillamine therapy in rheumatoid patients.

Facb rosette-forming cells in mice: studies on their functional significance

Lymphocytes bearing receptors for the Facb fragment of IgG have been shown previously to be elevated in the peripheral blood of patients with rheumatoid arthritis. The generation of these cells and their possible functional role in immune regulation have been investigated in mice. Facb rosette-forming (Facb-R+) lymphocytes were found to be elevated in the spleens of mice mounting a secondary plaque-forming cell (PFC) response to sheep erythrocytes but not during the primary response. Splenic Facb-R+ lymphocytes were also elevated when a cross-reacting antigen (goat erythrocytes) was used for the secondary immunization but not when a non-cross-reacting antigen (chicken erythrocytes) was used. Both primary and secondary immunization with bacterial lipopolysaccharide resulted in elevation of splenic Facb-R+ lymphocytes. Administration of antigen-specific Facb fragment in conjunction with antigen (calf erythrocytes) produced a suppression of the secondary PFC response. However, F(ab')2 fragments produced no such effect. This suppressive effect was shown to be antigen-specific since administration of Facb fragment of anti-calf erythrocyte IgG had no suppressive effect on the secondary PFC response to sheep erythrocytes. No change in splenic Facb-R+ lymphocytes was observed during delayed hypersensitivity responses to either sheep erythrocytes or the contact-sensitizing agent oxazolone. These results indicate that Facb-R+ lymphocytes are generated during secondary humoral responses but not cell-mediated immune responses, and suggest that these cells may exert a suppressive influence on antibody production. These findings are discussed in relation to the occurrence of these cells in patients with rheumatoid arthritis.

D-penicillamine withdrawal in rheumatoid arthritis

Thirty-eight patients with rheumatoid arthritis in remission on penicillamine were entered into a prospective, randomised, placebo controlled study to determine the effects of gradual penicillamine withdrawal, to find a serological marker capable of predicting relapse, and to assess the effects of reintroduction of penicillamine. 80% of patients attempting gradual penicillamine withdrawal flared. There was no single serological marker capable of predicting outcome consistently. Decreasing SH levels were highly specific for recurrence of active synovitis but were insensitive. Reintroduction of penicillamine was successful. The implications of these findings, particularly concerning duration of therapy with disease modifying drugs, are discussed.

Low density lymphocytes: their relationship to disease activity and to antirheumatic therapy

The acquisition of low density by lymphocytes is the earliest detectable marker of their activation and may be utilized for the separation and quantification of these cells. Low density lymphocytes (LDL) are found in increased numbers in patients with rheumatoid arthritis compared with healthy controls (p less than 0.05). The number of LDL is raised in patients who failed to respond clinically to gold or D-penicillamine when compared with those who did respond (p less than 0.05), the latter group having LDL values in the normal range. Sequential studies have shown that successful antirheumatic therapy is associated with a return to normal LDL levels (p less than 0.01) and that any alteration occurs by three months. LDL are particularly associated with synovitis and there was a close correlation (p less than 0.01) with the Compound Thermographic Index in the sequential study, as well as with other markers of synovitis, but not with systemic disease. LDL thus appear to be important markers of the synovitis of rheumatoid arthritis and they may represent a population of lymphocytes closely involved in the maintenance of synovial inflammation.

The oxidation of serum sulph-hydryl groups by hydrogen peroxide secreted by stimulated phagocytic cells in rheumatoid arthritis

Levels of free sulph-hydryl (SH) groups are depressed in the sera of patients with rheumatoid arthritis, especially during active disease. However, the mechanism underlying this effect is not known. We have investigated several oxidative species generated during the inflammatory process for their ability to react with serum SH in vitro. Our results show that serum oxidase enzymes (e.g. caeruloplasmin) do not have this activity but that "active oxygen species" generated either by an enzymatic reaction (xanthine plus xanthine oxidase) or by neutrophils stimulated with heat-aggregated IgG cause rapid oxidation of serum SH groups. The use of selective inhibitors of active oxygen species has demonstrated that this reaction is mediated by hydrogen peroxide. This compound is secreted in considerable amounts by activated phagocytic cells, especially neutrophils. Thus, serum SH levels may reflect phagocytic activity in patients with rheumatoid arthritis. We suggest that serum SH groups act as important extracellular scavengers of peroxides and so help to protect cells from damage by these molecules.

Effect of a specific iron chelating agent on animal models of inflammation

Iron is an important catalyst of oxidative radical reactions and promotes the formation of the hydroxyl radical from the superoxide anion radical and hydrogen peroxide. The stimulatory effect of the hydroxyl radical on lipid peroxidation prompted the speculation that free iron may directly promote inflammation and that iron chelating agents may have useful anti-inflammatory properties. This hypothesis is tested in animal models of inflammation with a specific iron chelating agent, desferrioxamine. At low doses (6 . 6 mg/kg) intraperitoneal desferrioxamine stimulated the induction of acute foot pad swelling in rats by monosodium urate but at higher doses (above 200 mg/kg) it suppressed this inflammatory reaction. A similar anti-inflammatory effect was observed in carrageenan-induced foot pad swelling. In guinea-pigs in which a Glynn-Dumonde synovitis was induced with bovine gammaglobulin, desferrioxamine (100 mg/kg) stimulated the acute inflammatory induction phase of this chronic allergic monoarthritis model. Repeated administration of desferrioxamine (100 mg/kg) from the seventh to the twelfth day after intra-articular challenge with bovine gammaglobulin markedly depressed the chronic inflammatory phase. In-vitro experiments suggest that desferrioxamine inhibits iron-catalysed lipid peroxidation when it is poorly saturated with iron, but loses this effect when it is iron saturated. Such an effect may explain our results with desferrioxamine in the animal studies and suggests that effective iron chelation and its removal may modify the inflammatory process in man.