Regulation of interleukin-2 production in rheumatoid arthritis

The regulation of interleukin-2 (IL-2) production was investigated using mononuclear cells from synovial fluid (SF) and peripheral blood of 12 patients with classical and active rheumatoid arthritis. Decreased phytohemagglutinin (PHA) stimulated IL-2 production by lymphocytes was observed in rheumatoid peripheral blood (5.3 +/- 10.9 units/ml) and SF (3.8 +/- 5.2 units/ml) compared to peripheral blood from 12 normal donors (18.1 +/- 15.4 units/ml) and SF from 5 patients with other rheumatic diseases (11.9 +/- 10.9 units/ml). Indomethacin, phorbol myristate acetate and irradiation of suppressor cells increased IL-2 values in rheumatoid SF and peripheral blood but did not restore normal IL-2 production. IL-2 production did not correlate with clinical activity in patients with RA.     

Interleukin 2 and interleukin 2 inhibitors in human serum and synovial fluid. II. Mitogenic stimulation, interleukin 2 production and interleukin 2 receptor expression in rheumatoid arthritis, psoriatic arthritis and Reiter's syndrome

Peripheral blood and synovial fluid (SF) mononuclear cells from 30 patients with rheumatoid arthritis (RA) were hyporesponsive to mitogenic stimulation with plant lectins and CD3 antibodies, due to depressed interleukin 2 (IL-2) production and IL-2 receptor upregulation. In contrast, in the seronegative arthritis patient group only SF mononuclear cells were hyporesponsive to mitogenic stimulation and there were no significant differences in IL-2 production or IL-2 receptor upregulation as compared with control subjects. No significant correlations were observed between IL-2 inhibitor levels and mitogenic responses, IL-2 production and IL-2 receptor upregulation on peripheral blood and SF mononuclear cells but an inverse correlation was noted between SF mitogenic responses and the expression of selected activation markers. We conclude that IL-2 abnormalities appear to be most pronounced in RA compared with other inflammatory arthritides and that these changes do not appear to be directly related to serum or SF IL-2 inhibitor levels.     

Inhibitor of interleukin-2 synthesis and response in rheumatoid synovial fluid

We studied the effects of a factor present in rheumatoid arthritis (RA) synovial fluid (SF) on interleukin-2 (IL-2)-dependent cell proliferation and on the production of IL-2 by mitogen-stimulated peripheral blood mononuclear cells. RA SF suppressed the responsiveness of a mouse T cell line (HT-2) to IL-2, indicating that it contained an inhibitor of the IL-2 response. When RA SF was fractionated by Sephadex G-200 gel filtration, the inhibitory activity was detected mainly in fractions with a molecular weight of approximately 150,000, but was also found in a 15-19-kd fraction. Removal of IgG from the 150-kd fraction, by means of an anti-IgG affinity column, did not reduce the activity of the fraction, nor was activity found in the eluted IgG. The inhibitory fractions reduced mouse thymocyte proliferative responses to IL-1 in the presence of phytohemagglutinin, and reduced the production of IL-2 by human peripheral blood mononuclear cells, but did not inhibit IL-1-induced human foreskin fibroblast proliferation; this suggests that the factor was not an IL-1 inhibitor. The inhibitory activity of the RA SF factor was blocked by an antibody against an inhibitor of IL-2 that was purified from a culture of the human monocytic leukemia cell line, THP-1. This finding also supports the conclusion that RA SF contains an IL-2 inhibitory factor. The observed inhibition of both IL-2 synthesis and IL-2 response suggests that the target of the inhibition was the T lymphocyte.     

Spontaneous IL-2 production in vitro in two patients with pure red cell aplasia

Summary We investigated spontaneous cytokine production in two patients with pure red cell aplasia (PRCA). The peripheral blood mononuclear cells (PBMNC) from two patients produced IL-2. Cyclosporin A (CyA) suppressed in vitro IL-2 production in one patient, but not in the other. Spontaneous IL-2 production disappeared in one patient 10 months after the start of CyA therapy. The patient for whom CyA therapy was stopped after the disappearance of spontaneous IL-2 production has remained in continuous remission for 1 year. The present case suggests that spontaneous IL-2 production in PBMNC might be an indicator of disease activity.     

IL-2诱导类风湿关节炎与骨关节炎T淋巴细胞STAT3 STAT5酪氨酸磷酸化状态的比较

目的观察白细胞介素(IL)-2作用于类风湿关节炎(RA)与骨关节炎(OA)外周血T淋巴细胞前后,T淋巴细胞中STAT3及STAT5的酪氨酸磷酸化活化状态,并进行比较.方法从RA与OA患者的外周血中分离培养单个核细胞,继而纯化得到T淋巴细胞,静息后,用重组人IL-2刺激,在各时相裂解细胞,收获提取蛋白,进行Western blot分析.结果在静息后,RA与OA的外周血T淋巴细胞中STAT3与STAT5均处于极低水平磷酸化的状态;在IL-2作用后,T淋巴细胞中STAT3和STAT5发生时相性的酪氨酸磷酸化,而RA的T淋巴细胞磷酸化程度较OA显著增高.结论IL-2对RA患者T淋巴细胞的STAT3和STAT5过度激活,引起T淋巴细胞中IL-2信号传导的异常放大效应,可能在RA的发病过程中发挥重要作用.     

Prostaglandin E2, interleukin 1 and gamma interferon production of mononuclear cells of patients with inflammatory and degenerative joint diseases

Inflammatory joint diseases exhibit distinct pathohistological and immunological characteristics. The studies performed demonstrated that in comparison to normal controls peripheral blood mononuclear cells from patients with rheumatoid arthritis (RA) presented an increased percentage of monocytic cells. Peripheral blood mononuclear cells from patients with RA produced significantly increased amounts of prostaglandin E2 and significantly decreased amounts of interferon-gamma following mitogen stimulation with LPS or PWM respectively. The spontaneous production of interleukin 1 was found to be elevated. A significantly increased LPS induced production of prostaglandin E2 could also be observed in monocyte depleted rheumatoid peripheral cells and in peripheral cells of patients with osteoarthritis and HLAB27 associated joint diseases. Mononuclear cells from rheumatoid synovial tissue produced increased amounts of prostaglandin E2 and decreased amounts of interferon-gamma; the spontaneous prostaglandin E2 production was similar to the values obtained by mitogen stimulation which may originate from the distinct cellular composition of synovial tissue.     

Interleukin 2 production and responsiveness in active and inactive rheumatoid arthritis

The interleukin 2 (IL-2) production and responsiveness of peripheral blood lymphocytes from patients with rheumatoid arthritis (RA) with active or inactive disease was compared with that of normal control donors. IL-2 production was assessed using a cellular interleukin assay in which an IL-2 dependent cell line was cocultured with varying numbers of irradiated IL-2 producing lymphocytes from the different donor sources. Cells from patients with active disease showed a significantly different pattern of IL-2 production from that of control or inactive RA patients in that a lower number of cells supported growth of the IL-2 dependent cell line. In one patient this shift in pattern was shown to correlate with change in disease activity. Lymphocyte responsiveness to IL-2 as determined by limiting dilution analysis did not differ significantly between the different groups. The results are consistent with a hyperproduction of IL-2 in RA during active disease.     

The relative proportions of secreted interleukin-2 and interleukin-10 determine the magnitude of rheumatoid arthritis T-cell proliferation to the recall antigen tuberculin purified protein derivative

OBJECTIVE: To investigate the mechanisms of the deficient proliferative responses by rheumatoid arthritis (RA) peripheral blood T cells to the recall antigen tuberculin purified protein derivative (PPD). METHODS: The concomitant production of interleukin (IL)-2, IL-10 and lymphocyte proliferation were studied by enzyme-linked immunosorbent assay and [(3)H]thymidine uptake, respectively, in 12 normal controls and eight RA patients. RESULTS: An inverse correlation was found between IL-10 production and proliferation to PPD. The proliferative response was shown to be critically affected by the IL-2:IL-10 ratio so that absolute levels of secreted IL-2 or IL-10 correlated non-significantly with lymphocyte proliferation. CONCLUSION: The deficient T-cell proliferation in RA peripheral blood mononuclear cells is related to the relative proportions of IL-2:IL-10 rather than the absolute amounts secreted.     

Targeting interleukin-15 in patients with rheumatoid arthritis: a proof-of-concept study

OBJECTIVE: Interleukin-15 (IL-15) is a proinflammatory, innate response cytokine that mediates pleiotropic effector function in rheumatoid arthritis (RA) inflammatory synovitis. Our objective was to study the ability of HuMax-IL15, a human IgG1 anti-IL-15 monoclonal antibody, to neutralize exogenous and endogenous IL-15 activity in vitro and to perform a phase I-II dose-escalation trial with HuMax-IL15 in patients with active RA. METHODS: Mononuclear cells from blood and synovial fluid (SF) of RA patients were isolated and cultured in vitro under experimental conditions involving the addition of HuMax-IL15. HuMax-IL15 was administered to 30 RA patients who received no other disease-modifying antirheumatic drugs in a 12-week, dose-ascending, placebo-controlled, double-blind, phase I-II proof-of-concept study. RESULTS: In vitro studies showed that HuMax-IL15 suppressed proliferation and induced apoptosis in an IL-15-dependent cell line, BDB2, and was capable of suppressing the release of interferon-gamma by synovial fluid mononuclear cell (SFMC) cultures induced by exogenous IL-15. Furthermore, HuMax-IL15 F(ab')2 fragments suppressed exogenous IL-15-induced CD69 expression in RA peripheral blood mononuclear cells and SFMCs, which indicates that HuMax-IL15 can specifically neutralize several biologic effects of IL-15 in synovial tissue in vitro. In a phase I-II clinical trial, HuMax-IL15 was well tolerated clinically, with no significant effects on T lymphocyte subset and natural killer cell numbers. Substantial improvements in disease activity were observed according to the American College of Rheumatology criteria for 20% improvement (63% of patients), 50% improvement (38%), and 70% improvement (25%). CONCLUSION: These clinical data suggest for the first time that IL-15 could represent a novel therapeutic target in RA.     

The effects of methotrexate on the production and activity of interleukin-1

To explore the possibility that the mechanism of action of methotrexate (MTX) in rheumatoid arthritis (RA) is related to modulation of interleukin-1 (IL-1), the effects of MTX on IL-1 production and activity were evaluated. Human peripheral blood mononuclear cells and murine peritoneal and splenic cells were stimulated by lipopolysaccharide to produce IL-1. No inhibition of IL-1 synthesis or secretion caused by MTX treatment could be demonstrated either in vitro or in vivo, in patients with RA or in mice treated with MTX. We did show, however, that MTX had an inhibitory effect on IL-1 activity in 2 assays that demonstrate 2 different functions of IL-1. In a 2-step assay using LBRM-33-1A5 (1A5) and CTLD cells, MTX inhibited the secretion of IL-2 by 1A5 lymphoma cells in response to phytohemagglutinin and IL-1. In an assay using D10.G4.1 (D10) cells, MTX inhibited IL-1-induced proliferation of the D10 T cell clone. No effect of the drug on IL-2 activity was observed. The results demonstrate that MTX is capable of inhibiting some IL-1 activities without affecting IL-1 production or secretion. We propose that the inhibition of IL-1 activity or IL-1-dependent events may be one of the mechanisms of action of MTX in RA.     

The effect of methotrexate (MTX) on expression of signalling lymphocytic activation molecule (SLAM) in patients with rheumatoid arthritis (RA) and its role in the regulation of cytokine production

OBJECTIVE: To investigate the effect of methotrexate (MTX) on cytokine production by activated CD4+ T-cells in patients with rheumatoid arthritis (RA). METHODS: The effect of MTX on intracellular expression of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), and cell surface expression of signalling lymphocytic activation molecule (SLAM) from freshly isolated peripheral blood mononuclear cells (PBMCs), and after in vitro culture with or without MTX, was analysed with flow cytometry in 18 patients with RA and 20 healthy controls. RESULTS: Intracellular expression of IFN-gamma and IL-4 on freshly isolated CD4+ T-cells was significantly higher in patients with RA than in the controls (p<0.05). Intracellular expression of both IFN-gamma and IL-4 after culture with MTX was significantly lower than those after culture without MTX in patients with RA. Although no significant difference was observed in SLAM expression on freshly isolated CD4+ T-cells between patients with RA and the controls, MTX significantly decreased SLAM expression on both activated IFN-gamma+ and IL-4+CD4+ T-cells in patients with RA. CONCLUSION: In vitro modulation of the cytokine network by MTX, IFN-gamma, and IL-4 is one of the major targets for MTX, and production of IFN-gamma and IL-4 by PBMCs may be suppressed by SLAM on activated CD4+ T-cell in patients with RA.     

Cytokines and the chronic inflammation of rheumatic disease. III. Deficient interleukin-2 production in rheumatoid arthritis is not due to suppressor mechanisms

Despite the evidence for activated T cells in the joint in rheumatoid arthritis (RA), there is evidence of deficient lymphocyte proliferation to a variety of stimulants. We investigated the production of interleukin-2 (IL-2) after phytohemagglutinin (PHA) stimulation. We show that in the peripheral blood IL-2 production was similar in RA and controls (3.7 vs 3.0 U/ml, respectively). However, blood lymphocytes from patients with joint effusions produced significantly less IL-2 than from patients without effusions (1.8 vs 5.7 U/ml, respectively). The amount of IL-2 produced by synovial fluids (SF) cells was significantly less than that produced by the corresponding blood cells (1.0 vs 1.6 U/ml). Further experiments revealed that the decreased IL-2 production was not due to its removal by IL-2 receptor positive cells in the SF and cell mixing experiments did not reveal any suppressor influences.     

A study of the effect of rheumatoid synovial fluid on proliferation and IL-2 production by total mononuclear cells and purified CD4+ cells of synovial fluid and peripheral blood

T cells from synovial fluid (SF) of rheumatoid arthritis (RA) patients have previously been shown to proliferate less after mitogenic stimulation and produce less interleukin 2 (IL-2) than normal T cells. To test whether SF is responsible for the reduced T-cell responses, we studied the effect of inflammatory SF on peripheral blood (PB) RA and normal mononuclear cells (MNC) and CD4+ T cells and on RA SF MNC and CD4+ cells in vitro. Most rheumatoid SF present in concentrations of 50% and 5% during in vitro stimulation increased mitogen-induced IL-2 production and proliferative response by normal PB and RA MNC and CD4+ cells. Other rheumatoid SF samples did not influence the T cell responses, while only a few samples had an inhibitory effect. The results indicate that SF contain both stimulatory and inhibitory factors and that the resultant effect on T cells may depend on the net effect of these. The results do not support the hypothesis that the apparently impaired function of SF T cells is due to contact with SF.     

Synovial cell secretion of IL-2 in vitro, a limiting dilution analysis

Limiting dilution analysis (LDA) was used to analyze the defect of production of IL-2 by synovial fluid cells in rheumatoid arthritis (RA). LDA is a relatively simple means of separating T-cell function from the potential effects of accessory-cells, suppressor factors and adsorption. The number of precursor cells for interleukin-2 (IL-2) secretion was determined among peripheral blood cells (PBL) from healthy control individuals, and in PBL and synovial fluid (SF) mononuclear cells from patients with rheumatoid arthritis (RA). Although the frequency of such cells in the PBL of the controls and RA patients was similar, that of the SF was significantly lower (about one sixth). This difference could not be accounted for by an inability of the SF cells to proliferate in culture, by the presence of suppressor cells, by absorption of IL-2, or by a relative lack of accessory-cell function in the SF fraction. Culturing synovial cells without stimulant for three days resulted in a two- to three-fold increase in the apparent frequency of secreting cells, but the same proportional increase followed similar manipulation of peripheral blood cells. Pre-incubation of normal lymphocytes in RA synovial fluid did not result in suppression of their ability to secrete IL-2. We conclude that the poor secretion of IL-2 after mitogen stimulation of SF cells is an intrinsic property of the T-cell, and not due to the presence of other factors. There was no evidence that this defect was selectively reversible by "resting" the cells prior to culture.     

Partial purification and characterization of systemic lupus erythematosus derived factors that suppress production of interleukin-2

We report here on interleukin-2 (IL-2) suppressive factors, synovial fluid (SF) peripheral blood mononuclear cells (PBM), derived from short term cultures of unstimulated PBM of patients with systemic lupus erythematosus (SLE). SF PBM suppressed production of IL-2, but not proliferative responses to this lymphokine. It was sensitive to acid (pH 2.6), heat (56 degrees C), and tryptic digestion. It retained activity in the presence of 2-mercaptoethanol (2-ME), had no interferon activity and no non-specific cytotoxicity. Although crude SF PBM contained IgG and PGE2, these were not associated with its 2 active fractions. SF PBM was partially purified on a G-200 Sephadex column. IL-2 suppressive activity was detected in 2 fractions of molecular weights corresponding to greater than 150 kD and 40-60 kD, the latter acting only in the presence of monocytes. SF PBM appear to affect directly the IL-2 producer cell, since it suppressed IL-2 production by (1) mitogen stimulated PBM depleted of CD8+ suppressor cells and by (2) mitogen induced Jurkat cells. These "spontaneous" suppressive factors were ubiquitous in SLE, and may be important tools for studying the defective IL-2 production in SLE and its significance in the development of the disease.     

Decreased production of suppressive-B-cell factor by synovial membrane B-lymphocytes in rheumatoid arthritis

Suppressive-B-cell factor (SBF) is an autoregulatory B-cell lymphokine produced by heat-aggregated-IgG stimulated B-lymphocytes which suppresses polyclonal immunoglobulin production. SBF production by rheumatoid arthritis (RA) patients' peripheral blood B-lymphocytes inversely correlates with disease activity and in vitro rheumatoid factor production. To further define the role of SBF in the pathogenesis of RA, the present study measured SBF production by surgically-obtained synovial membrane mononuclear leukocytes. SBF production by RA synovial leukocytes was similar to the levels previously described for RA peripheral blood leukocytes. Both RA and osteoarthritis (OA) synovial leukocytes produced significantly less SBF than leukocytes obtained from otherwise healthy patients with plica. OA patients produced less SBF than RA patients, but the difference was not statistically significant. SBF values for combined RA patients and controls with OA or plica correlated with the degree of histological plasma cell infiltration providing further evidence for SBF production by cells of the B-lymphocyte lineage. Depletion studies also demonstrated that synovial SBF was produced by B-lymphocytes. The molecular weight (34,000) of synovial SBF was similar to the molecular weight of peripheral blood SBF. Decreased SBF production by RA synovial B-lymphocytes is a functional abnormality in RA which may contribute to the perpetuation of synovial rheumatoid factor production and chronic synovial inflammation.     

Enhanced interleukin 1 and depressed interleukin 2 production in juvenile arthritis

Blood mononuclear cells from a total of 23 children with juvenile arthritis were stimulated in vitro to produce interleukin 1 (IL-1) and interleukin 2 (IL-2) and compared with age matched healthy controls. Peripheral blood monocytes from patients with juvenile arthritis produced a higher amount of IL-1 than controls, whereas peripheral blood lymphocytes from the same patients produced lower amount of IL-2 than controls. These findings could not be explained by concurrent therapy. The increase of IL-1 production was more marked in patients with active disease and therefore may have been secondary to the pathological process. However, the decrease of IL-2 production did not depend on disease activity, thus suggesting an immunoregulatory abnormality.     

Enhanced in vitro induced production of interleukin 10 by peripheral blood mononuclear cells in rheumatoid arthritis is associated with clinical response to methotrexate treatment

OBJECTIVE: To investigate the effect of in vivo treatment with methotrexate (MTX) on the regulation of ex vivo interleukin 10 (IL-10) production by peripheral blood mononuclear cells (PBMC) derived from patients with rheumatoid arthritis (RA). METHODS: Spontaneous as well as lipopolysaccharide (LPS) and phytohemagglutinin (PHA) induced IL-10 release was assessed by a specific immunoassay in culture supernatants of PBMC derived from 32 patients with active RA before and 6, 12, and 24 weeks after MTX treatment. IL- 10 production was correlated to the clinical response. As a control, IL-10 release from PBMC of 7 healthy blood donors was determined. RESULTS: PBMC of patients with RA showing > 50% improvement of the Paulus index after 3 and 6 months of MTX treatment (responders; n = 18) exhibited significantly enhanced IL-10 production after in vitro stimulation with LPS, whereas constitutively released IL-10 was below the detection limit of the immunoassay in all patients and controls. In contrast, IL-10 release from LPS stimulated PBMC of RA patients who showed < 20% improvement by Paulus index (nonresponders; n = 14) or who even deteriorated compared to baseline disease activity was markedly downregulated during MTX treatment in vivo. PHA-induced IL-10 release from PBMC in vitro was not significantly affected by MTX in vivo whether RA patients responded or not to MTX. CONCLUSION: Enhanced ex vivo LPS induced IL-10 production by PBMC of patients with RA is associated with a favorable therapeutic response to MTX treatment, whereas reduced production coincides more closely with disease deterioration or insufficient response. This may reflect both disease outcome upon treatment and/or the mode of the antiinflammatory action of MTX in RA. Because the LPS--but not the PHA--induced ex vivo IL-10 production by PBMC was stimulated by MTX in vivo, monocytes seem to be the prominent target cells for this drug mediated antiinflammatory cytokine regulation.