Enhanced production of interleukin-2 in patients with progressive systemic sclerosis. Hyperactivity of CD4-positive T cells?

Cytokines Involved in the Pathogenesis of SSc and Problems in the Development of Anti-Cytokine Therapy

Systemic sclerosis (SSc) is a connective tissue disease of unknown etiology. SSc causes damage to the skin and various organs including the lungs, heart, and digestive tract, but the extent of the damage varies from patient to patient. The pathology of SSc includes ischemia, inflammation, and fibrosis, but the degree of progression varies from case to case. Many cytokines have been reported to be involved in the pathogenesis of SSc: interleukin-6 is associated with inflammation and transforming growth factor-β and interleukin-13 are associated with fibrosis. Therapeutic methods to control these cytokines have been proposed; however, which cytokines have a dominant role in SSc might differ depending on the extent of visceral lesions and the stage of disease progression. Therefore, it is necessary to consider the disease state of the patient to be targeted and the type of evaluation method when an anti-cytokine therapy is conducted. Here, we review the pathology of SSc and potential cytokine targets, especially interleukin-6, as well as the use of anti-cytokine therapy for SSc.

Serum Levels of Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) in a Group of Patients with Systemic Sclerosis

In this report we investigate the behaviour of the serum levels of Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) in the course of Systemic Sclerosis (SS). This cytokine is produced mainly by T and NK cells, and its possible role in the pathogenesis of SS has not been previously described in the literature. Serum GM-CSF levels were assayed in 10 female patients, ageing from 35 to 70, affected by SS. These patients were not suffering from other disorders and were not being treated with steroids or immunosuppressive drug. A solid phase immunoenzymatic method was used to assess the serum levels of GM-CSF. Reference values were previously determined in a control group of 36 healthy women blood donors (19 premenopausal and 17 postmenopausal) (x̄=20.1 ±12.3 pg/ml). All the patients but one showed significantly increased serum levels of GM-CSF (x̄= 120.9 ±125.5 pg/ml). The highest levels were found in the two oldest patients, who also had the longest clinical history of SS, but a clear correlation with age, disease duration or clinical manifestations was not evident, even if the postmenopausal age group patients showed a higher mean value of GM-CSF (x̄= 148.0±144.1 pg/ml) than that found in the premenopausal age group (x̄= 57.7±1.4 pg/ml) (in contrast with the findings in the control group). The absence of other pathogenic conditions in our patients suggests that the increase in serum levels of GM-CSF might be linked to the fibroblast proliferation which is typical of SS. However, our results do not explain the role played by this factor in the fibroblastic proliferation process and an in vitro study is necessary to clarify this aspect.

Decreased expression of Runx1 and lowered proportion of Foxp3⁺ CD25⁺ CD4⁺ regulatory T cells in systemic sclerosis

OBJECTIVES

To investigate the role of Foxp3(+) CD25(+) CD4(+) regulatory T cells (Treg) and their transcription factor, Runt-related transcription factor 1 (Runx1), in the pathogenesis and development of systemic sclerosis (SSc).

METHODS

We collected 23 blood samples from patients with SSc including 19 females and 4 males, 11 early-stage cases within 3 years from onset and 12 late-stage cases and 22 samples from age-matched healthy subjects (HS). Total CD4(+) T cells were assessed for the expression of Treg-related markers, CD25 and CD127, on their surface and intracellular Foxp3 using flow cytometry. Relative expression of Runx1 mRNA in magnetically purified Treg was analyzed using real-time PCR.

RESULTS

Proportion of Foxp3(+) cells in total CD4(+) T cells was decreased in patients with either early- or late-stage SSc compared with that in HS, and Runx1 mRNA expression in purified Treg was lower in patients with SSc than in HS. Runx1 mRNA expression level was related to the frequency of Treg in SSc.

CONCLUSIONS

This is the first report on Runx1 expression in Treg of a human autoimmune disease. Low expression of Runx1 along with reduced proportion of Treg in CD4(+) T cells may be associated with development of SSc even in early disease.

Alterations of mononuclear inflammatory cells, CD4/CD8+ T cells, interleukin 1beta, and tumour necrosis factor alpha in the bronchoalveolar lavage fluid, peripheral blood, and skin of patients with systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a multisystem disease with underlying immune mechanisms.

AIMS

To investigate the clinicopathological characteristics of the lesions; immunological alterations in the bronchoalveolar lavage fluid (BALF), peripheral blood, and skin; and correlations between the clinicopathological characteristics and immunological alterations in SSc.

MATERIALS/METHODS

Skin biopsies, BALF, and peripheral blood samples were obtained from 19 patients (18 women, one man) with SSc and six age and sex matched healthy controls (HCs). Mononuclear inflammatory cells (MICs), CD4/CD8 cells, tumour necrosis factor alpha (TNFalpha), and interleukin 1beta (IL1-1beta) concentrations were examined in all samples using histological methods, enzyme linked immunosorbent assay, and immunoperoxidase staining.

RESULTS

The mean (SD) age of the patients with SSc was 34.8 (2.6) years. Proteinuria, positive rheumatoid factor, and C reactive protein were seen in 15.8%, 26.3%, and 26.3% of patients, respectively. Compared with HCs, there were significantly higher: total MICs (macrophages, lymphocytes), neutrophils, and eosinophils in BALF, blood, and skin (all p<0.05); cytokine concentrations in BALF (TNFalpha, p<0.001; IL-1, p<0.01) and peripheral blood (p<0.01 and p<0.05); and CD8/CD4+ T cells in peripheral blood (p<0.05). Compared with HCs, lesional skin had significantly higher histiocyte cell counts (p<0.05), lower lymphocyte counts (p<0.05), and higher CD4/CD8 ratios (p<0.001). There were significant correlations between cytokine concentrations and CD8+ T cells and forced vital capacity (p<0.001 and p<0.01, respectively).

CONCLUSIONS

MICs, CD4/CD8+ cells, and cytokines are altered in SSc. These alterations correlated with the underlying disease process and therefore may have pathogenic, modulatory, and potential prognostic roles in SSc.

Gammadelta receptor bearing T cells in scleroderma: enhanced interaction with vascular endothelial cells in vitro

In view of the documented perivascular mononuclear cell infiltration in the involved organs in scleroderma (SSc) and the reported accumulation of gammadelta-T cells in SSc skin and lung, we evaluated gammadelta-T cell interaction with endothelial cells (EC) in vitro. gammadelta- and alphabeta-T cells were isolated from BPMN of SSc patients with early diffuse disease and of matched control subjects by an immunomagnetic method after stimulation with mycobacterium lysate and interleukin-2 for 2 weeks. Lymphocyte adhesion, proliferation, and cytotoxicity to EC were investigated. SSc gammadelta-T cells adhered to cultured EC and proliferated at higher rates than control cells. Furthermore, significant EC cytotoxicity by SSc gammadelta was seen. The cytotoxicity was blocked by addition of anti-gammadelta-TCR antibody and by anti-granzyme A antibody but not by anti-MHC class I and II antibodies. Expression of granzyme A mRNA was seen in five/five SSc gammadelta-T cells and in one/five control cells. alphabeta-T cells from both SSc and control subjects were significantly less interactive with EC than gammadelta-T cells. The data demonstrate EC recognition by SSc gammadelta-T cells and propose gammadelta-T cells as a possible effector cell type in the immune pathogenesis of SSc.

Enhanced production of transforming growth factor-beta (TGF-beta) during autologous mixed lymphocyte reaction of systemic sclerosis patients

Systemic sclerosis (SSc) is characterized by systemic fibrosis and microvascular lesions. As TGF-beta is suggested to be related to skin fibrosis, we examined the production of TGF-beta from peripheral mononuclear cells (MNC) of SSc patients. Since anti-TGF-beta neutralizing antibody improved the defective proliferative response in autologous mixed lymphocyte reaction (AMLR) of SSc patients, TGF-beta was thought to participate in the decreased AMLR of SSc patients. Greater amounts of TGF-beta in the active as well as in the latent forms were produced during AMLR of SSc patients than that of normal subjects. It was suggested that TGF-beta excessively produced from the MNC of SSc patients might play a major role in the fibrosis of the patients during AMLR-like in vivo responses.

Analysis of proteins that interact with the IL-2 regulatory region in patients with rheumatic diseases

In order to investigate transcriptional regulation of lymphokine genes in rheumatic diseases, peripheral blood mononuclear cells from patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and systemic sclerosis (SSc) were analysed for expression of DNA-binding proteins. Nuclear extracts prepared from unstimulated and mitogen-activated cells were studied for their ability to bind to 32P-labelled oligonucleotides containing the AP-1, NF-AT, NF-B and CD28RC sites of the IL-2 promoter. Using gel mobility-shift assay, detection of protein binding to the AP-1 site was reduced in SLE compared with controls. NF-AT binding activity was enhanced in all groups of patients, and was associated with measures of disease activity in RA. In addition, SSc patients showed increased NF-kappa B binding activity. Altered patterns of DNA-binding proteins suggest disturbed intracellular signalling which may contribute to abnormal lymphokine production in rheumatic diseases.

Demonstration of interleukin-2, interleukin-4 and interleukin-6 in sera from patients with localized scleroderma

Localized scleroderma has been reported to be accompanied by immunological abnormalities related to B cells, but little is known about T-cell activation in this disease. In this study, serum levels of interleukin-2 (IL-2), interleukin-4 (IL-4) and interleukin-6 (IL-6), which are known to be released by activated T cells, were determined using a sensitive enzyme-linked immunosorbent assay in 48 patients with localized scleroderma and 20 with systemic sclerosis, and in 20 healthy control subjects. IL-2, IL-4 and IL-6 were detected in serum from patients with localized scleroderma but not in that from healthy controls. The presence of antihistone antibodies correlated significantly with elevated IL-4 and IL-6 levels. Decreased serum levels of IL-2, IL-4 and IL-6 paralleled improvement in cutaneous sclerosis. Frequent detection of these lymphokines in serum from patients with localized scleroderma reflects T-cell activation in this disorder.

Role of T cells and cytokines in effecting fibrosis

A number of humoral and cellular immune abnormalities are present in patients with early scleroderma (systemic sclerosis). Most of these abnormalities reflect ongoing autoimmune reactions of the cellular and humoral types, resulting in a variety of autoantibodies to cellular and tissue constituents. Evidence exists for a defect(s) in immunoregulation favoring excessive helper T cell activity. The presence of circulating cytokines and shed interleukin-2 receptors suggest ongoing cellular immune reactions are occurring, generating cytokines and lymphokines that are capable of effecting the vascular and fibrotic lesions that are hallmarks of the disease. Future directions for research are suggested that would focus on determining if, and at what point, fibroblasts might function autonomously to generate excessive matrix components and on determining the nature of the original antigenic stimulus that starts the scleroderma process.

Cytokines in rheumatic diseases

IL-1 and related cytokines have multiple biologic activities relevant to the rheumatic diseases. In addition to mediating inflammatory and immune responses, these proteins regulate many aspects of connective tissue metabolism. The cytokines interact in complex cascades: because of this, and various technical reasons, the exact role of cytokines in the pathogenesis of rheumatic diseases remains uncertain. However, considerable experimental data suggest that the abnormal regulation of cytokines contributes to such siseases as inflammatory arthritis, systemic lupus erythematosus, scleroderma, and dermatomyositis. Animal models of these diseases have contributed to understanding the role of cytokines in pathogenesis. Furthermore, drugs useful in treating these diseases affect cytokine pathways; some cytokines, their antagonists, or related substances have been used therapeutically to treat rheumatic diseases. The therapeutic use of these agents will likely increase as knowledge about the role of cytokines in the pathogenesis of rheumatic diseases expands.

CD4+ and CD8+ subsets: naive and memory cells in the peripheral blood of patients with systemic sclerosis

Systemic Sclerosis (SSc; scleroderma) is associated with several immunological abnormalities, including altered proportion between lymphocyte subsets. Peripheral blood lymphocyte subsets from 25 patients with SSc were studied by two-colour flow cytometry using monoclonal antibodies against CD45RA and CD29 markers, which allow a dissection of CD4+ and CD8+ populations into 'naive' and 'memory' subsets. A decrease of the percentage of CD8+ (p < 0.05) and of CD8+CD29+ (p < 0.001) cells was observed compared to that in 20 age and sex-matched controls. These abnormalities were not significantly associated with the extension of cutaneous disease or other clinical features of SSc nor with treatment, pattern of autoantibodies or HLA phenotype.

The kinetics of lymphocyte subsets and macrophages in subarachnoid space after subarachnoid hemorrhage in rats

BACKGROUND AND PURPOSE

Although it has been suggested that humoral immunity plays a role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage, there has been no quantitative assay for cellular immunity. We studied the kinetics of immune cells in the subarachnoid space after subarachnoid hemorrhage in the rat.

METHODS

One hundred fourteen Sprague-Dawley rats were used in this study. The animals were divided into two groups and injected with either autologous blood (0.3 mL) or saline into the major cistern. They were killed at the specified time: 10 minutes or 1, 2, 3, 5, or 7 days after subarachnoid hemorrhage. For immunohistochemical analysis, the rats' whole brains were frozen, and cryostat sections were prepared. For flow cytometric analysis of immune cell presence, their whole brains underwent enzymatic digestion.

RESULTS

Histopathologic study revealed pathological change of the arterial wall, and immunohistochemical study revealed the existence of macrophages and T cells in the subarachnoid space in animals with a survival time of 2 to 5 days after subarachnoid hemorrhage. A flow cytometric study revealed the peak of appearance of T cells and macrophages 2 days after subarachnoid hemorrhage. The helper-suppressor T cell ratio also reached a peak 2 days after subarachnoid hemorrhage.

CONCLUSIONS

A serial response of immunoreactive cells, which resembles that of the chronic allergic reaction observed in autoimmune diseases or delayed-type hypersensitivity, exists in the subarachnoid space after subarachnoid hemorrhage. The present results suggest that the initial response in cellular immunity, which is followed by humoral immunity and eicosanoid reactions, plays a role in eliciting the development of cerebral vasospasm.

Early phenotypic activation of circulating helper memory T cells in scleroderma: correlation with disease activity

OBJECTIVES

The differential expression of several accessory/activation molecules (CD26, CD29, CD45RA, CD25, MLR4, HLA-DR) on peripheral blood CD4+ and CD8+ T lymphocytes in patients with scleroderma was compared with that in controls and patients with other connective systemic diseases to look for evidence of the involvement of T cells in the disease process of scleroderma.

METHODS

The two colour expression of surface molecules by circulating T cells was analysed with a panel of monoclonal antibodies and flow cytometry in 17 patients with scleroderma, 10 patients with systemic lupus erythematosus, and five patients with rheumatoid arthritis, and the results compared with those for 10 normal controls. The two colour T CD4+ phenotype was further compared between patients with active and quiescent disease in these patients with scleroderma. The coexpression of surface molecules by CD4+ T cells was also analysed by three colour flow cytometry in eight patients with scleroderma.

RESULTS

Patients with scleroderma showed increased CD4+CD26+ and CD4+CD25+ percentages and absolute numbers and decreased CD8+CD29+ percentages compared with controls. Moreover, a significant correlation between the higher CD4+CD26+ T cell percentage and absolute cell numbers with disease activity was observed. Most of the CD4+ peripheral blood T cells from patients with scleroderma showed the CD26+CD45RA- phenotype by three colour flow cytometry analysis.

CONCLUSIONS

The distinctive pattern of early helper memory T cell activation in these patients with rapidly evolving scleroderma supports the role of a T cell mediated mechanism in the progression of scleroderma.

Avian scleroderma: evidence for qualitative and quantitative T cell defects

T cell activation is dependent upon calcium influx and protein kinase C activation, with subsequent lymphocyte proliferation dependent upon IL-2. Abnormalities in T cell proliferation, including abnormal calcium influx and defective protein kinase C activation, have been identified in aged mice and humans and many autoimmune diseases including diabetes, lupus and scleroderma. Since UCD line 200 chickens, which spontaneously develop a scleroderma-like disease, have both thymic defects and a diminished peripheral blood lymphocyte response to IL-2, we have further investigated T cell function in these birds. Interestingly, line 200 T cells respond poorly in vitro to a variety of diversely acting T cell mitogens including concanavalin A, phytohemagglutinin and anti-chicken CD3 monoclonal antibody. Moreover, they do not respond well even to phorbol myristate acetate in conjunction with ionomycin. Addition of exogenous IL-2-containing supernatant concurrently with mitogenic stimulation also had no significant effect. Analysis of intracellular free calcium demonstrated that the lymphocytes from diseased birds had a reduced influx of calcium (or release for intracellular stores) following stimulation. These data clearly reflect a unique defect in T cell activation associated with avian scleroderma. Analysis of chicken CD3, CD4 and CD8 expression revealed a 39% decrease in peripheral blood CD4+ cells in scleroderma birds, although this decrease was not sufficient to explain the 80-90% decrease observed in proliferation assays and calcium influx. Our data support the hypothesis that avian scleroderma is mediated via abnormal function of lymphocyte co-stimulatory molecules or intracellular calcium regulators.

Imbalance of CD4+ lymphocyte subsets in patients with mixed connective tissue disease

CD4+ (helper/inducer) T lymphocyte subsets were studied in the peripheral blood from patients with mixed connective tissue disease (MCTD) by double-labelling immunofluorescence. The proportion of CD4+CD45RA+ cells was higher (P less than 0.01) when compared with controls, whereas CD4+CD29+ cells were markedly diminished (P less than 0.001). CD4+CD29+ cells were lower than in patients with progressive systemic sclerosis who were studied in parallel. Upon stimulation with phytohaemagglutinin, CD4+ cells from MCTD patients showed a strong reactivity to acquire the CD29+ phenotype. Expression of high levels of CD29 and other adhesion molecules might lead to facilitated localization of CD4+ cells to inflamed tissue. It is suggested that an increased responsiveness of CD4+ cells to activation signals in vivo and accumulation of CD4+CD29+ cells at tissue sites could result in depletion of this cell subset in the peripheral blood of patients with MCTD.

Enhanced expression of high-affinity interleukin-2 receptors in scleroderma: possible role for IL-6

Scleroderma (systemic sclerosis) is characterized by tissue fibrosis, a distinctive vascular and microvascular disorder, and a perivascular mononuclear cell infiltration of involved organs. The pathogenesis of scleroderma is not known; however, there is evidence for a cell-mediated immune mechanism in the disease. Enhanced IL-2 production has been documented both in vivo and in vitro. In this study, the effect of IL-2 on lymphocyte proliferation in vitro was examined. An enhanced proliferative response to IL-2 was seen in scleroderma lymphocytes over that in matched control lymphocytes. Since high-affinity IL-2 receptors (HIL-2-R) mediate the growth-promoting activity of IL-2, we examined HIL-2-R expression on lymphocytes from 13 scleroderma and 11 matched control subjects by a radioiodinated IL-2 binding assay. Significantly higher numbers of HIL-2-R were noted in scleroderma cells (3054 +/- 618 in scleroderma vs 1721 +/- 181 in control cells, mean +/- SD; P less than 0.001). The addition of IL-6 to control cell cultures 24 hr prior to binding determination led to changes in IL-2 binding that were identical to scleroderma cell binding characteristics, while the addition of neutralizing IL-6 antibody to scleroderma cells led to a reduction in HIL-2-R expression. Other cytokines (IL-1, IL-3, IL-4, IL-5, TNF, LT, IFN-gamma, and TGF-beta) had no effect on IL-2 binding, suggesting that IL-6 may mediate the enhanced expression of HIL-2-R. This conclusion was further supported by the finding that scleroderma lymphocytes released in vitro 10- to 20-fold higher concentrations of IL-6 than control cells. The data demonstrate an amplification of IL-2 binding in scleroderma and suggest IL-6 as the mediator of this phenomenon.

Phenotypic analysis of skin infiltrates in comparison with peripheral blood lymphocytes, spleen cells and thymocytes in early avian scleroderma

University of California at Davis line 200 (UCD-200) chickens develop a hereditary connective tissue disease characterized by severe lymphocytic infiltration, vascular occlusion and fibrosis of skin and internal organs. To identify cellular immunological abnormalities in the acute inflammatory disease stage of this animal model for progressive systemic sclerosis (PSS) we investigated the phenotypic characteristics and function of peripheral blood lymphocytes (PBL), spleen cells and thymocytes in comparison with skin infiltrating cells. Immunofluorescence and immunohistochemical analysis using monoclonal antibodies revealed the overwhelming majority of skin infiltrating mononuclear cells in the deeper dermis and subcutaneous tissue to be T cell receptor alpha/beta (TcR2)+/CD3+/CD4+/class II+ cells, a small portion (5-10%) of which were interleukin 2 (IL-2) receptor positive. In contrast, the inflammatory infiltrate in perivascular areas of the papillary dermis was constituted of mainly TcR gamma/delta (TcR1)+/class II- lymphocytes. Only few B cells (T/B cell ratio greater than 5) were detected. These diseased chickens showed significantly reduced percentages and numbers of circulating peripheral T cells exhibiting TcR1, TcR2, CD3, CD4 or IL-2-receptor, probably owing to an increased influx into lymphoid organs and affected tissues. In contrast to healthy chickens, the thymi of UCD-200 animals revealed fewer cells expressing TcR1, TcR2 and class II antigen, suggesting an altered intrathymic maturation of the T cell lineage. Functional in vitro studies showed a significantly decreased T cell mitogen-induced proliferation rate associated with a decreased capacity to produce IL-2 and to express IL-2 receptors. In contrast to the deficient in vitro IL-2 production the sera of UCD-200 chickens contained significant levels of IL-2 bioactivity. The alteration of T lymphocyte physiology in UCD-200 chickens adds, at least in part, to the parallels between this animal model and its human counterpart. These data confirm our hypothesis that the PSS-like disease of UCD-200 chickens includes a numeric and/or functional alteration of peripheral T cell subsets, especially of TcR1 positive cells, in contrast to the pronounced accumulation in the afflicted tissues.

Detection of circulating Fc epsilon R2/CD23+ monocytes in patients with rheumatic diseases

Recently, in vitro studies have demonstrated that expression of Fc epsilon R2/CD23 on normal monocytes can be specifically induced by IL-4. In order to investigate the interaction of IL-4 and monocytes in rheumatic diseases, flow cytometry studies were performed. Elevated numbers of circulating Fc epsilon R2/CD23+ monocytes were detected in patients with progressive systemic sclerosis (PSS) as compared with controls. In addition, supernatants derived from phytohaemagglutinin-stimulated peripheral blood mononuclear cells of PSS patients contained high activity to induce Fc epsilon R2/CD23 on CD14+ monocytes. An increased frequency of Fc epsilon R2/CD23+ monocytes was also observed in rheumatoid arthritis, and sequential studies in patients with systemic lupus erythematosus showed a close relationship between Fc epsilon R2/CD23+ monocytes and disease activity. It is suggested that IL-4 has an important role in the pathogenesis of PSS by activating monocytes, and might also contribute to monocyte activation in other rheumatic diseases.

Abnormalities of T lymphocyte subsets in systemic sclerosis demonstrated with anti-CD45RA and anti-CD29 monoclonal antibodies

T cell subpopulations were assessed by two colour flow cytometry with phycoerythrin conjugated anti-CD45RA and anti-CD29 and fluorescein conjugated anti-CD4 and anti-CD8 monoclonal antibodies, on peripheral blood lymphocytes from 12 patients with systemic sclerosis and from nine control subjects. The percentage of CD4+CD29+ cells was significantly higher in patients with systemic sclerosis than in controls (mean (SEM) 68.8 (3.1) v 47.9 (4.1) respectively). CD4+CD45RA+ cells were not significantly different in patients and controls. CD8+CD29+ and CD8+CD45RA+ subpopulations were significantly higher in patients with systemic sclerosis than in controls (83.0 (3.2) v 58.7 (6.8) and 80.2 (3.0) v 66.9 (3.2) respectively). The increase in the percentage of CD29+ cells suggests an activation of memory cells in patients with systemic sclerosis, which may play an important part in the pathogenesis of the disease.

Increased interleukin-2 production in response to human type I collagen stimulation in patients with systemic sclerosis

Peripheral blood mononuclear cells (PBMC) from patients with systemic sclerosis (SSc) produced increased amounts of interleukin-2 (IL-2), in a dose-dependent manner, in response to stimulation with human type I collagen, whereas PBMC from normal subjects did not. At a dose of 50 micrograms human type I collagen/10(6) PBMC, PBMC from SSc patients (n = 17) produced 8 times as much IL-2 as did PBMC from 16 normal subjects (P less than 0.005) and 3 times as much as did PBMC from a group of 13 rheumatoid arthritis patients (P less than 0.05). In contrast, IL-2 production by PBMC after nonspecific stimulation with the mitogen, phytohemagglutinin, did not differ among the SSc, rheumatoid arthritis, and normal control groups. Cell depletion experiments indicated that the IL-2-producing cells in SSc patients are CD4+. Thus, SSc patients have CD4 cells that are specifically sensitized to human type I collagen and can produce increased levels of IL-2. Measurement of IL-2 production stimulated by human type I collagen may be useful in evaluating disease activity, and further investigation of this process may contribute to the delineation of the pathogenesis of SSc.

Enhanced CD3-mediated T lymphocyte proliferation in patients with systemic lupus erythematosus

Nonfractionated peripheral blood lymphocytes from patients with systemic lupus erythematosus (SLE) showed enhanced proliferative responses when stimulated via the CD3 pathway. In contrast, proliferative responses induced by phytohemagglutinin were diminished in SLE patients. Levels of CD3-induced interleukin-2 production and interleukin-2 receptor expression were comparable with normal levels. Highly purified T cells also showed augmented CD3 responses, but only in the presence of phorbol myristate acetate or a combination of phorbol myristate acetate plus calcium ionophore A23187, and not with calcium ionophore alone. The data suggest integrity of the T cell receptor/CD3 pathway for T cell activation in patients with SLE, as examined in cultures stimulated with specific anti-CD3 monoclonal antibodies rather than with multivalent lectins. An increased response via the CD3 complex could contribute to the autoimmune activity in human SLE.

Altered T cell subpopulations and lymphocytes expressing natural killer cell phenotypes in patients with progressive systemic sclerosis

Scleroderma (progressive systemic sclerosis [PSS]) is known to be associated with abnormal T cell immunoregulation. In the present study, we evaluated lymphocyte phenotypes in patients with PSS and normal control subjects by flow cytometry and monoclonal antibodies for total T (CD3), T suppressor (CD8), T helper (CD4), T helper-inducer (CDw29), T suppressor-inducer (CD45R), human leukocyte antigen, DR+B (CD19), DR+T, and natural killer subsets, HNK-1 (CD57) and NKH-1 (CD56) cells. Patients with PSS compared to normal subjects had significantly lower percentages of CD3+ (p less than 0.005) and CD8+ (p less than 0.05) (similar to several patients with rheumatoid arthritis also evaluated), as well as CD45R (p less than 0.05), T+DR+ (p less than 0.05), and NKH-1 (CD56) (p less than 0.0005) cells. Patients with PSS with late-limited or generalized disease had lower percentages of CD8+, CD19, NKH-1+, and CDw29, but higher percentages of CD4+, HNK-1, and CD45R cells compared to patients with early stage disease, but these results were not statistically significant. These unique alterations in patients with PSS may prove to be useful in monitoring the stage of disease activity for therapy and further define immunologic defects.

Soluble immunologic products in scleroderma sera

To investigate the role of immune mechanisms in scleroderma (systemic sclerosis, SSc), we measured the levels of selected cytokines and soluble immune markers in patient sera. Forty-two patients and 14 matched healthy controls are the subject of this report. In the SSc group, tumor necrosis factor (TNF) was found in 8/42 (29 +/- 539 pg/ml, mean level +/- SD) and lymphotoxin in 36/42 (1:409-1:200, serum dilution). Interleukin beta (IL-1 beta) was observed in 23/42 (44 +/- 29, U/ml). IL-2 was identified in 36/42 patients with a mean level of 286 +/- 406 U/ml, soluble interleukin-2 receptor in 42/42 (1055 +/- 393, U/ml), soluble CD4 antigen in 27/42 (1:10-1:320, serum dilution), and CD8 in 42/42 (470 +/- 134, U/ml). TNF, lymphotoxin, IL-1 beta, Il-2, and CD4 were not detected in the control group. IL-2 receptor levels in control subjects were 520 +/- 171 U/ml, significantly lower than those of scleroderma (P less than 0.001), and CD8 levels (582 +/- 140) were significantly higher than in scleroderma (P less than 0.05). The data suggest an ongoing activation of immune cells, particularly the CD4+ subset in SSc and indicate a potential role for the released mediator TNF, IL-1 beta, and lymphotoxin in the disease process.

Soluble interleukin-2 receptor, interleukin-2 and interleukin-4 in sera and supernatants from patients with progressive systemic sclerosis

We studied the sera of patients with progressive systemic sclerosis (PSS) for elevated levels of soluble interleukin-2 receptor (sIL-2R), interleukin-2 (IL-2) and interleukin-4 (IL-4). We also measured IL-2, IL-4 and B cell growth factor (BCGF) activity in supernatants of peripheral blood mononuclear cells from the same patients. The finding of elevated serum sIL-2R and IL-2, and the increased levels of IL-2, IL-4 and BCGF activity in culture supernatants indicates that T lymphocyte hyperactivity likely play a major role in PSS. The failure to detect under our experimental conditions a direct proliferative effect of recombinant IL-2 on enriched normal B cells might suggest that IL-4 is the cytokine mainly responsible of the BCGF activity recovered in PSS supernatants.

Enhanced production of interleukin-1 and tumor necrosis factor alpha by cultured peripheral blood monocytes from patients with scleroderma

Cultured peripheral blood mononuclear cells from 20 patients with scleroderma were shown to produce high levels of interleukin-1 alpha, interleukin-1 beta, and tumor necrosis factor alpha. There were positive correlations between the production of these 3 molecules. Purified monocytes from these patients produced much more tumor necrosis factor alpha than did those from normal subjects, even without lipopolysaccharide stimulation. These results show the hyperactivity of monocytes from scleroderma patients.

Immunoreactive growth hormone (GH) secretion by human lymphocytes: augmented release by exogenous GH

Peripheral blood mononuclear cells (PBMCs) from normal adults secreted small amounts of human growth hormone (GH; 0.2-0.6 pg/10(5) cells/7 days culture) as measured by a highly sensitive enzyme immunoassay. Stimulation of PBMCs with phytohemagglutinin (PHA) consistently showed a 4-6 fold increase in GH secretion. Transformed B-lymphocytes by Epstein-Barr virus also secreted GH (0.8-4.8 pg/5 x 10(4) cells/7 days culture). GH secreted by lymphocytes comigrated with pituitary GH on an Ultrogel AcA44 column. Addition of GH during the culture augmented endogenous GH secretion from PHA-stimulated PBMCs. GH-releasing hormone and a somatostatin analogue, SMS 201-995, did not affect GH secretion from non-stimulated and PHA-stimulated PBMCs. These findings suggest that both T and B lymphocytes secrete immunoreactive GH in a different manner from that in the anterior pituitary.

Increased proto-oncogene expression in peripheral blood T lymphocytes from patients with systemic sclerosis

The expression of c-myc, c-myb, and c-ras proto-oncogenes, determined using RNA hybridization techniques (slot-blot), was significantly increased in peripheral blood T lymphocytes, but not in B cells, from 17 patients with systemic sclerosis with diffuse scleroderma, compared with the expression in normal control subjects. The magnitude of expression of c-myc and c-myb tended to be higher in patients with early, active disease. These results demonstrate an in vivo activation of T cells from systemic sclerosis patients, which may play an important role in the pathogenesis of the disease.