Interleukin-2 receptor positive cells and circulating soluble interleukin-2 receptors in patients with solid tumors are not correlated

Activated lymphocytes can release a soluble form of IL-2 receptor (sIL-2R), which retains the capacity to bind IL-2. Abnormally high values of sIL-2R have been observed in patients with advanced solid tumors. In an attempt to further understand the biological significance of sIL-2R in solid tumors, this study investigated the relation between sIL-2R and Tac-positive cells. sIL-2R serum levels and Tac-positive cells were determined in 18 patients with solid tumors metastatic, 108 non-metastatic. Tumor types were: breast 7; lung 6; colon 2; stomach 1; testis 1; larynx 1. No correlation was found between circulating sIL-2R values and Tac-positive cells, and there was no difference between Tac-positive cell mean number in patients with high and normal sIL-2R levels. These preliminary results suggest that different mechanisms are responsible for sIL-2R release in the blood and IL-2 receptor expression on the immune cell surface.     

Effects of cancer chemotherapy on the relation between serum levels of soluble interleukin-2 receptors and CD4/CD8 ratio in patients with solid neoplasms

The clinical significance of sIL-2R in solid tumors has still to be clarified. To further define the biological role of sIL-2R in cancer and their relation to chemotherapy, we have measured serum levels of sIL-2R and CD4/CD8 ratio in 45 patients with limited or metastatic solid tumor, 28 of whom had never received chemotherapy, whereas the other 17 had been previously treated with chemotherapy. sIL-2R were significantly higher in metastatic cancer patients than in the non-metastatic ones, while no difference was seen between patients treated and untreated with chemotherapy. Within the untreated group, sIL-2R mean values were significantly higher in patients with low CD4/CD8 ratio than in those with the normal one, while an opposite behavior was seen in patients previously treated with chemotherapy. The present study shows that cancer chemotherapy influences the release of sIL-2R and its relation to T lymphocyte subpopulations.     

Clinical Significance of sIL-2R Levels in B-Cell Lymphomas

Elevated soluble interleukin-2 receptor (sIL-2R) in sera is observed in patients with malignant lymphoma (ML). Therefore, sIL-2R is commonly used as a diagnostic and prognostic marker for ML, but the mechanisms responsible for the increase in sIL-2R levels in patients with B-cell lymphomas have not yet been elucidated. We first hypothesized that lymphoma cells expressing IL-2R and some proteinases such as matrix metalloproteinases (MMPs) in the tumor microenvironment can give rise to increased sIL-2R in sera. However, flow cytometric studies revealed that few lymphoma cells expressed IL-2R α chain (CD25) in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL), and most CD25-expressing cells in the tumor were T-cells. Distinct correlations between CD25 expression on B-lymphoma cells and sIL-2R levels were not observed. We then confirmed that MMP-9 plays an important role in producing sIL-2R in functional studies. Immunohistochemical (IHC) analysis also revealed that MMP-9 is mainly derived from tumor-associated macrophages (TAMs). We therefore evaluated the number of CD68 and CD163 positive macrophages in the tumor microenvironment using IHC analysis. A positive correlation between the levels of sIL-2R in sera and the numbers of CD68 positive macrophages in the tumor microenvironment was confirmed in FL and extranodal DLBCL. These results may be useful in understanding the pathophysiology of B-cell lymphomas.     

Membrane-bound and soluble IL-2 receptors (p55 and p75 chains) on peripheral blood mononuclear cells from patients with solid malignancies

The aim of the investigation was to study directly the IL-2 receptor (IL-2 R) and its subunits, p55 and p75 chains, either membrane-bound or soluble, on PBMC of patients with solid malignancies and, indirectly, the same patients’ PBMC ability to produce IL-2. Fifty-eight cancer patients, 29 men and 29 women, were studied: their mean age was 57.3 yr, range 35–79. Twenty-two healthy age-sex-matched subjects served as controls. The tumors were the most common and the most representative among human cancers, i.e., breast, lung, head and neck, digestive tract and liver, prostate and gynecologic cancers: they were generally in advanced stages and in 23 cases metastatic. The PBMC proliferative response to PHA, PHA plus IL-2, and IL-2 was evaluated along with the response to PHA in the presence of anti-p55, anti-p75 monoclonal antibodies, or both. Moreover, membrane-bound IL-2 R (p55 and p75 chains) on PHA-stimulated PBMC was detected, along with soluble IL-2 R in the serum and in the culture supernatants. The conclusions suggest that in solid malignancies: the membrane-bound IL-2 Rs, both p55 and p75 chains, are expressed normally, there is an high serum level of soluble IL-2 R, there is a normal release of soluble IL-2 R in culture, and there is an indirect evidence of a lack of IL-2 production. Therefore, no primary impairment of IL-2 R was found in solid tumors. Moreover, in our study we have found no difference in any parameter studied between patients with and patients without metastases.     

Evaluation of serum levels of cytokines and intercellular adhesion molecule-1 (ICAM-1) in astrocytic tumours.

Soluble form of intercellular adhesion molecules (sICAM) are increased in serum of many inflammatory diseases and tumours: the expression of such molecules is regulated by cytokines. In the present paper serum levels of interleukin-2 (IL-2), soluble interleukin-2 receptor (sIL-2R) and sICAM-1 were evaluated in patients with glioma compared with different tumours (lung and kidney carcinoma) in order to investigate the compromise of the immune system in these malignancies and to understand the host defence mechanisms. 14 cases of astrocytomas (WHO grade II, III), 20 cases of glioblastomas (GBL, WHO grade IV), 5 cases of lung carcinoma and 6 cases of kidney carcinoma were studied; the results were compared with 15 healthy controls. IL-2, sIL-2R, sICAM-1 concentrations were assessed by an enzyme-linked immunosorbent assay (ELISA) technique. The results were analyzed by Student's t test. Our findings showed that serum levels of IL-2 and sIL-2R were increased in all cancer patients; on the contrary, sICAM-1 serum levels were not significantly increased in GBL and astrocytoma patients. The increased values of IL-2 and sIL-2R are in agreement with a depression of the immune reactivity in patients with glioblastoma and astrocytoma, as reported in literature. On the contrary the levels of sICAM-1 are unchanged in astrocytic tumours while patients with kidney carcinoma presented the higher levels and an unfavourable prognosis.     

Membrane-bound/soluble IL-2 receptor (IL-2R) and levels of IL-1α, IL-2, and IL-6 in the serum and in the PBMC culture supernatants from 17 patients with hematological malignancies

The present study investigated the peripheral blood mononuclear cells (PBMC) blastic responses to PHA, PHA plus recombinant IL-2 (rIL-2) and rIL-2 alone; the expression of membrane-bound IL-2R on PHA-stimulated PBMC; and the levels of IL-1α, IL-2, IL-6, and sIL-2R in serum and in culture supernatants from PHA-stimulated PBMC in 17 patients with hematological malignancies (mean age 58.5 yr, range 22–82): 6 with non-Hodgkin’s lymphoma (NHL), 4 with Hodgkin’s lymphoma (HL), 5 with Hairy cell leukemia, 1 with chronic myelogenous leukemia, and 1 with chronic lymphocytic leukemia. The patients with HL and NHL with active disease (AD) were separated from those in clinical remission. The patients with AD were studied at diagnosis (obviously before therapy) and the patients in clinical remission were out of therapy since at least 6 mo. The lymphocyte blastogenic response to PHA was significantly lower in patients with HL and NHL with AD than in the control group. The response to rIL-2 alone was in the same range in the control group and in HL and NHL AD patients. By adding rIL-2 to PHA there was an increase of the blastogenic response of the same patients. The percentage of CD25 expressed on PHA-stimulated lymphocytes from patients with HL and NHL AD and from normal subjects is in the same range. Serum levels of IL-2, IL-6, and sIL-2R were significantly higher in HL and NHL AD patients than in controls as well as in all other hematological malignancies. Supernatants derived from PHA-stimulated PBMC were assessed for the presence of cytokines and sIL-2R by ELISA. The levels of IL-2, IL-6, and sIL-2R were significantly lower in HL and NHL AD patients than in controls as well as in all other hematological malignancies.     

Biological significance of soluble IL-2 receptor

A NUMBER of receptors for growth factors and differentiation antigens have been found to be secreted or released by cells. Following mononuclear cell (MNC) activation and interleukin-2 receptor (IL-2R) expression, a soluble form of the Alpha;-chain of IL-2R (sIL-2R) is released. The sIL-2R has been shown to be present in the culture supernatants of activated MNCs as well as in normal sera and, in higher amounts, in sera from subjects affected by several diseases including neoplastic, infectious and autoimmune ones, and in sera from transplanted patients suffering allograft rejection. The blood sIL-2R levels depend on the number of producing cells and the number of molecules per cell, so that sIL-2R blood values may represent an index of the number and the functional state of producing cells, both normal and neoplastic. Thus, monitoring of the immune system, mostly T-cells and haematological malignancies might be targets for the measurement of sIL-2R. Since many conditions may influence sIL-2R production, little diagnostic use may result from these measurements. However, since blood sIL-2R levels may correlate with disease progression and/or response to therapy, their measurement may be a useful index of activity and extent of disease. The precise biological role of the soluble form of the IL-2R is still a matter of debate. However, we know that increased sIL-2R levels may be observed in association with several immunological abnormalities and that sIL-2R is able to bind IL-2. It is conceivable then that in these conditions the excess sIL-2R released in vivo by activated lymphoid cells or by neoplastic cells may somehow regulate IL-2-dependent processes. On the other hand, it cannot exclude that sIL-2R is a by-product without biological significance. Finally, it is puzzling that in many conditions in which an increase of blood sIL-2R values has been observed, MNCs display a decreased in vitro capacity to produce sIL-2R. These seemingly contrasting findings are discussed in the light of the data showing that sIL-2R production correlates with IL-2 production.     

Interleukin-6 and interleukin-6 receptor secretion by chronic lymphatic leukaemia and normal B lymphocytes: effect of PMA and PWM

Interleukin-6 (IL-6) and soluble interleukin-6 receptor (sIL-6R) were detected in supernatants of cultures of B chronic lymphatic leukaemia (CLL) lymphocytes. Phorbol-12-myristate 13 acetate (PMA) caused a decrease in the levels of IL-6 in 14 out of 16 cultures and an increase in levels of sIL6R in all 15 cases. The effect of pokeweed mitogen (PWM) was variable and not significant. The levels of IL-6 were below the detection limit (60 pg/ml) in sera of 13 CLL patients whereas sIL-6R was detected (13 ng/ml to 97 ng/ml) in the 13 sera. IL6 was not detected in cultures of unstimulated or stimulated with PMA or PWM normal human B cells. Levels of sIL-6R were minimal in cultures of normal B lymphocytes and were increased in PMA stimulated cultures. The results are consistent with the view that B-CLL cells produce spontaneously IL-6 which could act in an autocrine fashion to cause shedding of surface IL-6R and account for the correlation found between serum levels of sIL-6R and B-CLL lymphocyte numbers. The fall in levels of IL-6 in PMA stimulated CLL cultures might express masking or degradation of IL-6 after combination with the receptor.     

A soluble form of IL-13 receptor alpha 1 promotes IgG2a and IgG2b production by murine germinal center B cells.

A functional IL-13R involves at least two cell surface proteins, the IL-13R alpha 1 and IL-4R alpha. Using a soluble form of the murine IL-13R alpha 1 (sIL-13R), we reveal several novel features of this system. The sIL-13R promotes proliferation and augmentation of Ag-specific IgM, IgG2a, and IgG2b production by murine germinal center (GC) B cells in vitro. These effects were enhanced by CD40 signaling and were not inhibited by an anti-IL4R alpha mAb, a result suggesting other ligands. In GC cell cultures, sIL-13R also promoted IL-6 production, and interestingly, sIL-13R-induced IgG2a and IgG2b augmentation was absent in GC cells isolated from IL-6-deficient mice. Furthermore, the effects of the sIL-13R molecule were inhibited in the presence of an anti-IL-13 mAb, and preincubation of GC cells with IL-13 enhanced the sIL-13R-mediated effects. When sIL-13R was injected into mice, it served as an adjuvant-promoting production to varying degrees of IgM and IgG isotypes. We thus propose that IL-13R alpha 1 is a molecule involved in B cell differentiation, using a mechanism that may involve regulation of IL-6-responsive elements. Taken together, our data reveal previously unknown activities as well as suggest that the ligand for the sIL-13R might be a component of the IL-13R complex or a counterstructure yet to be defined.     

Fine needle aspiration cytology of neoplasms metastatic to the breast

The fine needle aspiration (FNA) cytologic findings in 18 cases of metastatic neoplasms of the breast are reported. The cases were encountered in a combined series of 2,529 FNA breast biopsies, of which 666 were malignant; the metastatic neoplasms of the breast thus constituted 2.7% of all the malignant breast tumors. The series consists of 15 women and 3 men, with a mean age of 48 years (range of 11 to 73 years). Sixteen biopsies confirmed metastatic malignancy in patients with known extramammary primaries; the prebiopsy clinical diagnoses in six of the patients were benign breast lesions. In eight patients, the clinical differential diagnosis was either a benign or malignant primary breast lesion versus a metastatic malignancy. In two additional patients, the FNA biopsy identified metastatic neoplasms from unsuspected extramammary primaries. The metastatic neoplasms included three small-cell carcinomas of the lung, one squamous-cell carcinoma of the lung, two malignant melanomas, three ovarian malignancies, including a dysgerminoma, and one each of carcinoma of the fallopian tube, endometrial carcinoma, transitional-cell carcinoma of the urinary bladder, prostatic carcinoma, acute granulocytic leukemia, lymphoma, mycosis fungoides, hepatoma and neuroblastoma of the retroperitoneum. Recognition of unusual cytologic patterns raised the suspicion of, or confirmed the diagnosis of, malignancy in all cases, with no false-negative diagnoses. None of the cases were cytologically interpreted as a primary breast malignancy. Ancillary studies performed on the FNA material, including immunocytochemistry, contributed to a definitive diagnosis in three cases. FNA diagnosis of metastatic malignancy of the breast is essential in order to avoid unnecessary mastectomy and to ensure appropriate chemotherapy and/or irradiation treatment.     

The clinical significance of serum soluble interleukin 2 receptor (sIL-2R) concentration in lung cancer

The activated mononuclear cells can release a soluble form of interleukin 2 receptor (sIL-2R) in the blood. Serum sIL-2R level is a sensitive and quantitative marker of circulating peripheral blood mononuclear cell activation. This molecule acts as an antagonist of IL-2-mediated responses. The present study was carried out to analyze the circulating levels of sIL-2R in lung cancer in relation to the histological type of the tumour, clinical stage, response to therapy, time survival for patients. The study included 62 patients (30 SCLC, 32 NSCLC) and 10 healthy subjects as controls. SIL-2R serum levels were measured with a sandwich enzyme immunoassay using commercial kits (ENDOGEN). The mean serum values of sIL-2R were significantly higher in cancer patients than in controls (p=0.01). There was no significant difference in relation to tumour histological type. Within the NSCLC chemotherapy group, sIL-2R mean levels observed at the end of chemotherapy were higher in the progressing patients than in the responding patients. The metastatic patients had higher levels of sIL-2R than those with locally limited disease. In the case of SCLC classified to extensive disease mean levels of sIL-2R were higher than SCLC classified to limited disease. The mean serum values of sIL-2R were significantly higher in weight loss patients than no weight ones (p=0.03). Within NSCLC group there was a correlation between sIL-2R mean levels and the age of patients (p=0.04). In SCLC group there was a correlation between levels of sIL-2R and time survival for patients (p=0.009).     

Soluble IL-2 receptor as an agent of serum-mediated suppression in human visceral leishmaniasis

In visceral leishmaniasis (VL), patient's lymphocytes are not activated by leishmania Ag stimulation, and their sera exhibit a potent nonspecific suppressive effect on the responses of normal lymphocytes. Sera were obtained from 33 VL patients, eight patients with subclinical VL, and from 27 normal volunteers. Only sera from VL patients markedly reduced Con A-induced lymphocyte proliferative responses, as well as IL-2 or IFN-gamma production by normal lymphocytes. Addition of exogenous human rIL-2 to cultures containing VL patient sera partially reversed the normal lymphocyte proliferative capacity and restored IFN-gamma production. This phenomenon was consistent with the presence of greatly elevated levels of soluble IL-2R (sIL-2R) in VL patients' sera (4299 +/- 2351 U/ml), well above those of normal sera (180 +/- 94 U/ml), or of sera from patients with subclinical leishmania infection without immunosuppression (1002 +/- 281 U/ml). Furthermore, the removal of sIL-2R reduced VL serum suppressive activity as evaluated by effects on IL-2 and on IFN-gamma production. These data suggest the participation of high levels of sIL-2R in the serum-mediated suppression in VL.     

IL-6 Amplifies TLR Mediated Cytokine and Chemokine Production: Implications for the Pathogenesis of Rheumatic Inflammatory Diseases

The role of Interleukin(IL)-6 in the pathogenesis of joint and systemic inflammation in rheumatoid arthritis (RA) and systemic juvenile idiopathic arthritis (s-JIA) has been clearly demonstrated. However, the mechanisms by which IL-6 contributes to the pathogenesis are not completely understood. This study investigates whether IL-6 affects, alone or upon toll like receptor (TLR) ligand stimulation, the production of inflammatory cytokines and chemokines in human peripheral blood mononuclear cells (PBMCs), synovial fluid mononuclear cells from JIA patients (SFMCs) and fibroblast-like synoviocytes from rheumatoid arthritis patients (RA synoviocytes) and signalling pathways involved. PBMCs were pre-treated with IL-6 and soluble IL-6 Receptor (sIL-6R). SFMCs and RA synoviocytes were pre-treated with IL-6/sIL-6R or sIL-6R, alone or in combination with Tocilizumab (TCZ). Cells were stimulated with LPS, S100A8-9, poly(I-C), CpG, Pam2CSK4, MDP, IL-1β. Treatment of PBMCs with IL-6 induced production of TNF-α, CXCL8, and CCL2, but not IL-1β. Addition of IL-6 to the same cells after stimulation with poly(I-C), CpG, Pam2CSK4, and MDP induced a significant increase in IL-1β and CXCL8, but not TNF-α production compared with TLR ligands alone. This enhanced production of IL-1β and CXCL8 paralleled increased p65 NF-κB activation. In contrast, addition of IL-6 to PBMCs stimulated with LPS or S100A8-9 (TLR-4 ligands) led to reduction of IL-1β, TNF-α and CXCL8 with reduced p65 NF-κB activation. IL-6/IL-1β co-stimulation increased CXCL8, CCL2 and IL-6 production. Addition of IL-6 to SFMCs stimulated with LPS or S100A8 increased CXCL8, CCL2 and IL-1β production. Treatment of RA synoviocytes with sIL-6R increased IL-6, CXCL8 and CCL2 production, with increased STAT3 and p65 NF-κB phosphorylation. Our results suggest that IL-6 amplifies TLR-induced inflammatory response. This effect may be relevant in the presence of high IL-6 and sIL-6R levels, such as in arthritic joints in the context of stimulation by endogenous TLR ligands.     

The significance of an increase in soluble interleukin-2 receptor level in colorectal cancer and its biological regulating role in the physiological switching of the immune response cytokine network from TH1 to TH2 and back

 Current research has still not clarified the biological role of soluble interleukin(IL)-2 receptor (sIL-2R) and the significance of its increase in the serum of colon cancer patients compared to healthy subjects. To address these questions at the immunological level in a group of patients and healthy subjects, we determined the sIL-2R level in the serum and its release from peripheral blood mononuclear cells (PBMC) as a function of tumour necrosis factor (TNF) α, IL-1α, IL-1β, IL-2, interferon (IFN) γ, IL-4, IL-6 and IL-10 levels in the serum and PBMC production; and PBMC proliferative responses to IL-2, IL-4 and anti-CD3 monoclonal antibody (CD3), variously combined. The level of sIL-2R in patients’ serum was higher than in healthy subjects and correlated with the stage of advancement. Moreover, while in healthy subjects the serum level of sIL-2R was not significantly correlated with other parameters, in patients it was positively related to IL-4, IL-6 and IL-10 serum levels, PBMC IL-4 production and to the PBMC proliferative response to CD3 and CD3+IL-2; it was negatively correlated to IL-2 serum level and IL-1β PBMC release. A negative connection between IFNγ serum level and the PBMC production of sIL-2R was also found. This suggests that the increase of sIL-2R in the serum of patients, compared to healthy subjects, is involved in the inappropriate expansion of the T helper (TH2) suppressive immune response, which we previously reported. The multivariate statistical method supported the above suggestions and we also found that, in healthy subjects, the up- and down-regulation of sIL-2R in the serum within the physiological ranges seems to have a regulating role in the relationships between TNFα, IFNγ and IL-4, IL-6, contributing to the operation of the cytokine network between TH1 and TH2 cells. However, in patients compared to healthy subjects the increased sIL-2R serum level seems to direct the immune response towards a suppressive type, which may be due to an alteration in the above-mentioned physiological regulating role. Received: 12 April 1997 / Accepted: 4 September 1997     

Soluble interleukin-2 receptor in stage I-III melanoma

The aim of the present study was to assess the prognostic value of soluble interleukin-2 receptor (sIL-2R) serum levels in stage I-III melanoma patients. The levels of sIL-2R were determined using an enzyme immunometric test kit in 329 patients affected by malignant melanoma (MM) from 1995 to 2004. Correlations between sIL-2R values, baseline patients and tumour features were studied by contingency tables and the chi-square test. The Kaplan-Meier product limit method was applied to plot disease-free survival (DFS) curves. Univariate analysis was performed with the Log-rank test. Cox proportional-hazards regression was used to analyse the effect of several risk factors on DFS. In total, 2330 blood samples were collected during follow-up of 329 MM patients. Forty-five (13.7%) patients had Breslow tumour thickness1.00 and 2.00 and 4.00 mm. Ulceration was present in 64 cases (19.4%). Thirty-nine sentinel lymph nodes (SLNs) (11.8%) were infiltrated by MM. Soluble IL-2R values ranged from 130 to 1420 U/ml; median value was 500 U/ml. One hundred twenty-one (36.8%) patients presented with sIL-2R>600 U/ml at first measure (FM), 194 patients (58.9%) with values increasing up to or more than 600 U/ml [increasing values (IV) pattern]. A correlation was found between Breslow's tumour values and the IV sIL-2R pattern group (P=0.0304 with chi2 test). Gender, presence of ulceration, Breslow tumour thickness, FM and IV sIL-2R pattern groups had a significant prognostic value for DFS. At multivariate analysis, presence of ulceration, gender, FM and IV sIL-2R pattern groups emerged as independent prognostic factors for DFS. The 5-year DFS rate was 88% for patients with FM<600 U/ml and 76.9% for patients with FM>600 U/ml. In IV pattern, the 5-year DFS rate was 69.5% compared to 87% for patients with no sIL-2R values>600 U/ml during follow-up. sIL-2R values are associated with progression of MM. Further studies are needed to address the role of the IL-2/IL-2R/sIL-2R axis in melanoma biology.     

Factors influencing the effect of the soluble IL-6 receptor on IL-6 responses in HepG2 hepatocytes

The soluble IL-6 receptor (sIL-6R) can increase IL-6-induced signalling by forming a complex with IL-6 and membrane-bound gp130 (the receptor beta chain which transduces signals). The conditions affecting this response to sIL-6R were studied using fibrinogen release from HepG2 hepatocytes. Exogenous sIL-6R had no effect alone or in the presence of a submaximal concentration of IL-6, but increased responses to supramaximal IL-6 concentrations in a concentration-related manner. Dexamethasone increased the expression of the membrane IL-6R and endogenous sIL6R release, and increased responses to supramaximal but not submaximal IL-6 concentrations. The amount of endogenous sIL-6R released is relatively small and is unlikely to influence the effects of the exogenous sIL-6R. The observed concentration-related decrease in sIL-6R production in the presence of IL-6 may indicate internalization of ligand/receptor complexes. This would significantly decrease the amount of IL-6R (soluble or membrane) available for signalling and limit continued functional response later in the cultures. These data indicate that the major factor influencing responses to exogenous sIL-6R is an excess of IL-6 which is necessary to form complexes with the sIL-6R, which can then interact with gp130 to increase signalling.     

Serum levels of interleukin-6 type cytokines and soluble interleukin-6 receptor in patients with rheumatoid arthritis.

We investigated the serum concentrations of interleukin-6 (IL-6) and two IL-6 family of cytokines (leukaemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) as well as IL-6 soluble receptor (sIL-6R) using an enzyme-linked immunosorbent assay (ELISA) in 66 patients with rheumatoid arthritis (RA) and 24 healthy controls. We examined a possible association between the serum levels of these peptides and RA activity according to the Mallya and Mace scoring system and Ritchie''s index. We also evaluated the correlation between the serum levels of IL-6, LIF, CNTF and sIL-6R and duration of the disease and calculated sIL-6R/IL-6 ratio in RA patients and in the control group. IL-6 and sIL-6R were detectable in all 66 patients with RA and 24 normal individuals. LIF was also found in the serum of all patients with RA and in 16 (66.7%) normal individuals. In contrast CNTF was measurable only in 15 (22.7%) patients with RA and 24 (33.3%) normal individuals. The highest IL-6 and sIL-6R levels were found in the patients with Stages 3 and 4 of RA activity and the lowest in the control group. In contrast there were no statistically significant differences between the LIF and CNTF levels in RA patients and normal individuals. We found positive correlation between IL-6 and sIL-6R concentrations and Ritchie''s index and a lack of such correlation with LIF and CNTF. IL-6 serum level correlated positively with the disease duration, but sIL-6R, LIF and CNTF did not. Serum sIL-6R/IL-6 ratio was significantly lower in RA patients than in healthy controls. In conclusion, an increase in the serum levels of IL-6 and sIL-6R, but not LIF and CNTF concentrations, may be useful markers for RA activity.     

Shedding of the interleukin-6 (IL-6) receptor (gp80) determines the ability of IL-6 to induce gp130 phosphorylation in human osteoblasts

Human osteoblasts produce interleukin-6 (IL-6) and respond to IL-6 in the presence of soluble IL-6 receptor (sIL-6R), but the cell surface expression of IL-6R and the mechanism of sIL-6R production are largely unknown. Three different human osteoblast-like cell lines (MG-63, HOS, and SaOS-2) and bone marrow-derived primary human osteoblasts expressed both IL-6R and gp130 as determined by flow cytometry and immunoprecipitation. However, the membrane-bound IL-6R was nonfunctional, as significant tyrosine phosphorylation of gp130 did not occur in the presence of IL-6. Phorbol myristate acetate induced a dramatic increase of both IL-6R shedding (i.e. the production of sIL-6R) and IL-6 release in osteoblast cultures, but the cell surface expression of gp130 remained unchanged. IL-6 complexed with sIL-6R, either exogenously introduced or derived from the nonfunctional cell surface form by shedding, induced rapid tyrosine phosphorylation of gp130. This effect was inhibited by neutralizing antibodies to either sIL-6R or gp130, indicating that the gp130 activation was induced by IL-6/sIL-6R/gp130 interaction. Protein kinase C inhibitors blocked phorbol myristate acetate-induced and spontaneous shedding of IL-6R resulting in the absence of sIL-6R in the culture medium, which in turn also prevented the activation of gp130. In conclusion, human osteoblasts express cell surface IL-6R, which is unable to transmit IL-6-induced signals until it is shed into its soluble form. This unique mechanism provides the flexibility for osteoblasts to control their own responsiveness to IL-6 via the activation of an IL-6R sheddase, resulting in an immediate production of functionally active osteoblast-derived sIL-6R.     

The level of interleukin-2 and of soluble interleukin-2 receptor in patients with Balkan nephropathy

Balkan Nephropathy (BN) is defined as a clinical entity with unknown etiology. The involvement of immune system in pathogenesis of BN is not well defined yet. The aim of this study was to gain more insight into the cellular immune mechanisms in BN. We determined some factors implied in cellular immunity, such as the serum level of IL-2 and of IL-2 soluble receptor (sIL-2R), and the presence of IL-2 receptor alpha chain (CD25) on T cells membrane. The study was performed on 15 patients with BN, 15 patients with Chronic Pyelonephritis (CPN), and 10 healthy controls from a non-endemic area. Our study showed no significant differences between IL-2 level and CD25+ cells percentage in CPN compared to controls, but a significantly increased level of sIL-2R. The BN sIL-2R is significantly lower than sIL-2R in CPN, and associates an important T cell activation (high CD25+ presence, elevated IL-2 level) compared to CPN. Our conclusion is that while the high sIL-2R level could down modulate T cell activity in CPN, BN sIL-2R level is ineffective in limiting the activation effects of IL-2 on T cells. The results suggest that cellular immunity could have a role in the pathogenesis of N.