High-affinity interleukin-2 receptors on blood lymphocytes are decreased during active rheumatoid arthritis

Comparison of blood and synovial fluid lymphocyte subsets in rheumatoid arthritis and osteoarthritis

Immunoregulatory T-cell deficiency is thought to underlie pathogenesis of rheumatoid arthritis (RA) as a systemic autoimmunopathy. The aim of this study was a simultaneous analysis of peripheral blood and synovial lymphocyte subsets (Ly-SS) of RA patients as compared to patients with locally active osteoarthritis (OA). Peripheral blood Ly-SS and paired synovial fluid Ly-SS from 87 RA patients were analysed by two dimensional flow cytometry (Simulset Becton Dickinson) as compared to 15 OA patients. The control group consisted of 32 healthy subjects. The peripheral blood analysis from RA and OA patients revealed a significant decrease of CD8+ T-cells and increase of CD4+: CD8+ ratio when compared to the control group. The blood of RA patients showed a significant increase of HLA DR+ and IL 2R+ T cells as compared to OA group. The synovial fluid from RA and OA patients showed a significant increase of CD3+, CD8+, HLA DR+ T-cells and decrease of CD4+:CD8+ ratio and CD19+ cells in comparison to the peripheral blood. This study shows, that the OA T-cell system seems not to be activated in peripheral blood in opposition to RA patients. Synovial fluid Ly-SS in OA, however, showed only quantitative but not qualitative differences. OA seems to be mainly a local inflammatory response depending on T-cells, when lymphocyte T activity in blood is diminished.

Abnormal T-cell function in patients with psoriatic arthritis: evidence for decreased interleukin 2 production

Psoriatic arthritis (PSA) is an inflammatory arthritis associated with psoriasis. Although not considered an autoimmune process, there is evidence for humoral and cellular immune abnormalities similar to autoimmune diseases such as rheumatoid arthritis and systemic lupus (SLE). We investigated mitogen-induced proliferation and interleukin 2 (IL-2) production by peripheral blood mononuclear cells in patients with PSA. Both IL-2 production and proliferation were significantly decreased in PSA patients when compared to controls. Increased arachidonic acid metabolism has been reported in skin and peripheral mononuclear cells of patients with psoriasis and PSA. We therefore also investigated the effect of indomethacin and prostaglandin E2 (PGE2) on IL-2 production. Addition of indomethacin to cultures did not significantly change IL-2 production in patients with PSA, but did so in controls. PGE2 produced a significant reduction in IL-2 production in PSA and in controls.

Serum concentrations of soluble interleukin 2 receptor in patients with rheumatoid arthritis: effect of second line drugs

Serum soluble interleukin 2 receptor (sIL-2R) concentrations reflect lymphocyte activation in vivo. An investigation was carried out to determine if sIL-2R concentrations correlate with existing disease activity parameters in patients with rheumatoid arthritis (RA) and whether these concentrations are modulated by treatment with second line drugs. Seventy nine patients with rheumatoid arthritis with active disease were prospectively treated with sodium aurothiomalate, auranofin, or sulphasalazine. Sequential concentrations of sIL-2R were measured by enzyme linked immunosorbent assay (ELISA). No correlations were observed between sIL-2R concentrations and clinical parameters and there were only moderate associations with concentrations of C reactive protein and the erythrocyte sedimentation rate. Concentrations of sIL-2R did not significantly change with treatment. It is concluded that sIL-2R probably measures an aspect of rheumatoid synovitis distinct from acute phase reactants and is not influenced by treatment with second line drugs.

Detection of cytokine receptors by high-sensitivity immunofluorescence/flow cytometry

Cytokines have profound effects on cells, and act through receptors which need only be at low concentrations (around 100 copies per cell) to transmit activation signals. The detection of such low concentrations is possible using monoclonal antibodies and fluorescence/flow cytometry, but only by using specialized techniques. The best results so far have been obtained using biotinylated second antibody followed by phycoerythrin-streptavidin, and batches of these reagents have to be carefully selected. Analysis of the fluorescence is best done using 546 nm excitation from a mercury arc lamp, but 512 nm excitation from an argon-ion laser can also be used. With appropriate alignment, instruments with 488 nm fixed-wavelength lasers can give sensitivity almost as good as the 546 nm system. Working at high sensitivity, background levels also increase, particularly for B lymphocytes. Background staining can be reduced to acceptable levels by blocking the two major mechanisms for non-specific binding. Applications of these methods to the detection of cytokine receptors on normal and malignant cells are reviewed.

Impaired generation of high-affinity interleukin-2 receptors in the autologous mixed lymphocyte reaction in rheumatoid arthritis

We examined the expression of high-affinity interleukin (IL)-2 receptors (IL-2R) as well as Tac and HLA-DR antigens on peripheral blood (PB) T cells from 11 rheumatoid arthritis (RA) patients and 8 healthy controls induced in the autologous mixed lymphocyte reaction (AMLR). The proportion of HLA-DR- and Tac-bearing T cells and expression of these activation antigens were higher in patients relative to controls (P less than 0.01) in freshly isolated unstimulated PB mononuclear cells. AMLR stimulation of RA T cells failed to induce an increase in the proportion of HLA-DR and Tac-bearing T cells which was observed in health controls. After AMLR stimulation the number of high-affinity IL-2R were significantly lower in RA patients compared with controls (P less than 0.01). The number of high-affinity IL-2R on patient T cells correlated strongly with AMLR reactivity as measured by [3H]thymidine incorporation (r = 0.821, P = 0.002). The results suggest that the AMLR defect in RA may result from impaired generation of high-affinity IL-2R.

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

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

Interleukin 4 inhibits polyclonal immunoglobulin secretion and cytokine production by peripheral blood mononuclear cells from rheumatoid arthritis patients

Rheumatoid arthritis (RA) is associated with T- and B-cell dysfunction. Immunoglobulin (Ig) production is under the control of T cells and their derived cytokines such as interleukin 2 (IL-2) and IL-4. Herein we studied the regulation of the production of immunoglobulins and cytokines by peripheral blood mononuclear cells from RA patients and controls. In the controls, IL-4 inhibited Ig production in response to Staphylococcus aureus and pokeweed mitogen stimulation. IL-2 induced maximal Ig production in association with Staphylococcus aureus, whereas it inhibited pokeweed mitogen-induced production. In patients, levels of Ig production in response to mitogens and cytokines were reduced, particularly for the response to IL 2. The inhibitory effect of IL-4 on mitogen-induced Ig production was observed in RA patients as in the controls. Spontaneous production of IL-6 was increased in RA patients. These levels were correlated with indicators of active disease such as sedimentation rate and Ritchie index. IL-4 inhibited the production of IL-6, IL-1 beta, and tumor necrosis factor alpha (TNF alpha) by both controls and rheumatoid patients. Thus as first described for the T-cell response, mononuclear cells from RA patients display a reduced response to mitogens and cytokines which induce their B-cell differentiation into Ig-screening cells. However, IL-4 was able to inhibit Ig and cytokine production, properties suggesting a potential antiinflammatory role for this cytokine.

Reconstitution of impaired autologous mixed lymphocyte reactivity in rheumatoid arthritis

We examined the ability of recombinant IL-2 to reconstitute the autologous mixed lymphocyte reaction (AMLR) defect in peripheral blood mononuclear cells (PBM) from patients with rheumatoid arthritis (RA). Our results revealed an ability to fully reconstitute RA AMLRs with pharmacologic concentrations (100 units/ml), but not physiologic concentrations (10 units/ml) of IL-2. Full reconstitution of RA AMLRs was achieved whether IL-2 was added as the initiation of culture or at 48 or 72 hours prior to termination of the cultures. Impaired IL-2 production was noted throughout the time course of the RA AMLRs. Neither an inhibitor of IL-1 nor IL-2 was detected in AMLR culture supernatants. Moreover, IL-1 in pharmacologic concentrations up to 50 units/ml failed to reconstitute impaired AMLR reactivity. In 2 patients whose AMLRs failed to reconstitute fully with 100 units/ml IL-2, addition of 10 units/ml IL-1 in combination with IL-2 fully reconstituted the AMLR defect. The results may suggest that defective IL-2 generation alone cannot fully account for impaired AMLR reactivity in RA patients.

Functional studies of soluble low-affinity interleukin-2 receptors in rheumatoid synovial fluid

Since abnormal regulation of interleukin-2 (IL-2) has been demonstrated in rheumatoid arthritis (RA), the functional role of low-affinity soluble IL-2 receptors (sIL-2R) purified from RA synovial fluids (SF) was studied. Picomolar levels of sIL-2R were detected in RA SF using an enzyme-linked immunosorbent assay. Levels were higher in serum and SF from RA patients than in controls (P less than 0.001) and higher in RA SF than in paired RA serum (P less than 0.01). Soluble IL-2R from RA SF had estimated molecular weights of 40-50 kd and 80-100 kd by gel filtration analysis. The 80-100-kd peak is likely to be a dimer of the 40-50-kd peak, since a single 45-kd peak was found after elution from sodium dodecyl sulfate-polyacrylamide gels. Since inhibitory activity for lymphocyte proliferation was found in the 80-100-kd range, the sIL-2R were purified with an anti-CD25 affinity column and further analyzed. The purified fractions did not interfere with the proliferation of mitogen-stimulated lymphocytes or with the binding of radiolabeled IL-2 to CTLL-2 cells, although direct binding of IL-2 was demonstrated. The affinity of sIL-2R from RA SF for binding IL-2 was in the range of 25 nM, which is similar to the affinity of sIL-2R purified from a human T cell clone, indicating that both sIL-2R are low-affinity receptors for IL-2. We conclude that the concentration and binding affinity of low-affinity sIL-2R purified from RA SF render them unable to interfere with IL-2-related activities.

Activation of T cell subsets in the peripheral blood of patients with Sjögren's syndrome. Multicolor flow cytometric analysis

Using 3-color flow cytometry, we determined the proportions of activated T cells (DR+), including CD4+ cells, CD8+ cells, and their subsets, in the peripheral blood of 17 patients with Sjögren's syndrome (SS). Activated T cells were significantly increased in CD4+ cells, CD8+ cells, and T suppressor inducer (CD4+, Leu-8+), T helper (CD4+, Leu-8-), and T cytotoxic (CD8+, CD11-) subsets, but not the T suppressor/natural killer subset (CD8+, CD11+), in patients with SS as compared with the controls. Furthermore, the proportions of activated T cells in the CD4+, Leu-8- subset, the CD8+ subset, or the CD8+, CD11- subset showed a positive correlation with serum gamma globulin levels in the SS patients. Our findings suggest that a certain immunoregulatory balance between T helper and T suppressor activities is maintained in SS patients, although this balance seems to occur at highly activated levels, and that quantitative changes of some lymphocyte subsets are important factors in maintaining this balance. We discuss the possibility that CD4+, Leu-8+ cells recirculate into peripheral lymph nodes, while CD4+, Leu-8- cells migrate into inflammatory tissues such as salivary glands, since the Leu-8 antigen is reported to be a homing receptor in peripheral lymph nodes. This process might be accelerated in SS, and each T cell subset may further participate in immunologic activation in the lymph nodes or target tissues.

In vitro production of interferon-gamma by peripheral blood from patients with Graves' disease, Hashimoto's thyroiditis and rheumatoid arthritis

The production of interferon-gamma (IFN-gamma) by peripheral blood mononuclear cells (PBMC), CD4 cells, or CD8 cells in response to interleukin-2 (IL-2) stimulation has been studied; the samples were obtained from 12 healthy control subjects, 19 patients with Graves' disease (10 hyperthyroid and nine euthyroid), 13 patients with Hashimoto's thyroiditis (four hypothyroid and nine euthyroid), and 15 patients with rheumatoid arthritis (11 active and four inactive). A dose of IL-2 (25 U/ml) was utilized to induce IFN-gamma by PBMC from all four groups. The incremental increase in IFN-gamma values (with IL-2 stimulation minus without stimulation) was significantly less in PBMC from patients with Graves' disease, Hashimoto's thyroiditis, and rheumatoid arthritis than that in PBMC from control subjects. The values from PBMC in patients with Graves' disease in a euthyroid state were below normal but greater than those from patients with Graves' disease in a hyperthyroid state. The incremental increase in IFN-gamma values from Graves' disease PBMC correlated with the serum TSH values (r = 0.622, P less than 0.01), but not with thyroid autoantibodies (anti-thyroid microsomal antibodies, anti-thyroid microsomal antibodies, nor TSH-binding inhibitory immunoglobulin activities). The incremental increase in IFN-gamma from PBMC from both control subjects and Graves' disease was correlated with that from CD4 cells (r = 0.711, P less than 0.01), but not with that from CD8 cells. The production of IFN-gamma in response to IL-2 from PBMC in Graves' disease correlated inversely with thyroid function, appearing to reflect the very effect of hyperthyroidism in this process. The precise explanation of these phenomena remains unclear. The decreased response of IFN-gamma to IL-2 stimulation by PBMC from patients with Graves' disease, Hashimoto's thyroiditis, and rheumatoid arthritis seems to be a non-specific phenomenon occurring in both organ specific autoimmune disease and systemic autoimmune disease. It may be due to a down-regulation in autoimmune disease of CD4 cells in response to IL-2, a decreased level of IL-2 cellular receptors or a decreased receptor affinity, associated increased soluble IL-2 receptors, or a defect of the intra-CD4 cellular IL-2 signal to produce or release IFN-gamma in the conditions studied.

Interleukin-2, soluble interleukin-2 receptor and tumor necrosis factor in sera from patients with rheumatoid arthritis

Interleukin-2 (IL-2), soluble interleukin-2 receptor (IL-2R) and tumor necrosis factor (TNF) have been measured in sera from 47 patients affected by classic rheumatoid arthritis (RA) using an enzyme-linked immunosorbent assay. The patients were divided into 4 groups as follows: group A, 18 patients with inactive disease; group B, 19 patients with active disease under treatment with non-steroidal antiinflammatory drugs (NSAID) and second-line drugs; group C, 5 patients with active disease under treatment with NSAID and cyclosporine A (CSA) for at least 4 months; group D, 5 patients in the same condition as patients of group C, but treated with azathioprine (AZA) instead of CSA. IL-2 was undetectable in all patients except two, both characterized by active disease. Soluble IL-2R levels were above the upper limit of the normal range in most of the patients studied, but the mean value ( +/- 1 SD) was significantly higher in patients of group B (1,288 +/- 421 U/ml) than in patients of group A (686 +/- 205 U/ml) and group C (842 +/- 414 U/ml). In two patients affected by active RA treated with pulse methylprednisolone therapy (1 g/day for 3 alternate days) the values of soluble IL-2R dropped from 948 to 662 U/ml and from 660 to 518 U/ml, respectively. No statistically significant correlation was observed between the serum level of IL-2R and the RF titre or percentage of C1q-binding activity, respectively. TNF was found within the normal range in all patients except one, who was characterized by active arthritis, high number of rheumatoid skin nodules and extremely high RF titre.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation pathways of synovial T lymphocytes. Expression and function of the UM4D4/CDw60 antigen

Accumulating evidence implicates a central role for synovial T cells in the pathogenesis of rheumatoid arthritis, but the activation pathways that drive proliferation and effector function of these cells are not known. We have recently generated a novel monoclonal antibody against a rheumatoid synovial T cell line that recognizes an antigen termed UM4D4 (CDw60). This antigen is expressed on a minority of peripheral blood T cells, and represents the surface component of a distinct pathway of human T cell activation. The current studies were performed to examine the expression and function of UM4D4 on T cells obtained from synovial fluid and synovial membranes of patients with rheumatoid arthritis and other forms of inflammatory joint disease. The UM4D4 antigen is expressed at high surface density on about three-fourths of synovial fluid T cells and on a small subset of synovial fluid natural killer cells; in synovial tissue it is present on more than 90% of T cells in lymphoid aggregates, and on approximately 50% of T cells in stromal infiltrates In addition, UM4D4 is expressed in synovial tissue on a previously undescribed population of HLA-DR/DP-negative non-T cells with a dendritic morphology. Anti-UM4D4 was co-mitogenic for both RA and non-RA synovial fluid mononuclear cells, and induced IL-2 receptor expression. The UM4D4/CDw60 antigen may represent a functional activation pathway for synovial compartment T cells, which could play an important role in the pathogenesis of inflammatory arthritis.

Lymphocyte surface marker expression in rheumatic diseases: evidence for prior activation of lymphocytes in vivo

Expression of major histocompatibility complex (MHC) class II and other lymphocyte activation markers on peripheral blood and synovial fluid T lymphocytes from patients with rheumatoid arthritis (RA), psoriatic arthritis, and Reiter's syndrome were measured and the mean fluorescence intensities of these antigens were assessed. Increased expression of MHC class II antigens of synovial fluid T lymphocytes is not unique to RA, though it is quantitatively greater on RA synovial fluid T cells. There was less expression of other lymphocyte activation markers (4F2, transferin receptor) and a marked discordance between the expression of these markers and the interleukin 2 receptor (IL2r). Synovial fluid T lymphocytes contain a subpopulation of larger cells expressing MHC class II and other lymphocyte activation antigens with the exception of the IL2r. Mean fluorescence intensity of CD3 and CD4 antigens on synovial fluid T lymphocytes was decreased in all three patient groups, suggesting prior in vivo exposure of synovial fluid T lymphocytes to an unknown antigen.