Clinical significance of elevated soluble interleukin-6 receptor levels in the sera of patients with plasma cell dyscrasias

Summary .We investigated the clinical significance of the serum soluble interleukin-6 receptor (sIL-6R) in 42 patients with plasma cell dyscrasias (27 with multiple myeloma (MM), 13 with monoclonal gammopathy of undetermined significance (MGUS), and two with plasma cell leukaemia (PCL)). Serum levels of sIL-6R in normal individuals were 77 ± 21 ng/ml (mean ± SD, n = 18); those in patients with MGUS and with MM were elevated (102 ± 33 ng/ml, mean ± SD, P < 0–05 and 126 ± 60ng/ml, mean ± SD, P < 0–01, respectively). Significant correlations were not found between the serum levels of sIL-6R and known prognostic factors (C-reactive protein, haemoglobin levels, calcium, creatinine, β₂-microglobulin, amounts of M-protein, or percentages of plasma cells in bone marrow). Elevated serum sIL-6R did not affect the survival of the patients with MM. Serial measurements of sIL-6R together with the clinical course of patients with plasma cell neoplasias revealed a good correlation between the sIL-6R level and disease activity. We conclude that sIL-6R can be used as a clinical factor correlated with the disease activity, at least in some patients with plasma cell neoplasias.     

Soluble interleukin-6 receptor as a prognostic factor in multiple myeloma

Interleukin-6 (IL-6) is a major growth factor for the clonal malignant plasma cells in multiple myeloma (MM). The effect of IL-6 may be enhanced by soluble IL-6 receptor (sIL-6R). As there is a clinical need for improved stratification of MM patients at diagnosis, we have studied the role of sIL-6R as a prognostic marker in 207 newly diagnosed MM patients. Serum sIL-6R concentration was above the upper reference limit in 47% of the patients at diagnosis. The concentrations of sIL-6R and two other prognostic factors, IL-6 and β-2 microglobulin (β2M), were all significantly higher in the patients who died within 3 years compared with those who survived. However, serum sIL-6R did not show linear correlation with IL-6 or β2M levels. In univariate logistic regression analysis sIL-6R was a significant predictor of 3-year mortality. Kaplan-Meier analysis showed that raised levels of sIL-6R were associated with shorter survival. When the patients were stratified into four groups according to their serum IL-6 and sIL-6R levels, the patients with normal serum levels of both parameters had clear survival benefit. As β2M was the most powerful prognostic factor in the multivariate analysis, the patients were also stratified according to their serum β2M and sIL-6R levels. The patients with raised levels of both β2M and sIL-6R had shorter survival than the patients in the other three groups. Thus, measurement of these parameters at diagnosis would help to stratify MM patients.     

Serum interleukin-6 (IL-6) and interleukin-4 (IL-4) in patients with multiple myeloma (MM)

In this study we determined, in patients with multiple myeloma (MM), serum levels of IL-4 and IL-6 at diagnosis and during the course of the disease, seeking a correlation with disease activity and prognosis. We studied 54 MM patients, 41 of whom responded to chemotherapy whilst 11 were resistant. At diagnosis, IL-6 was increased in 66% of patients (median 35.5 pg/ml) whereas IL-4 was low (median 4 pg/ml) in 75% of patients. In responding patients, IL-4 increased in remission (median 25 pg/ml), whereas IL-6 decreased (median 4 pg/ml). In chemotherapy-resistant patients, IL-6 and IL-4 values remained stable during the course of the disease.     

Soluble interleukin-6 receptor in rheumatoid arthritis

Abstract

To investigate the pathophysiologic role of soluble interleukin-6 receptor (sIL-6R) in patients with rheumatoid arthritis (RA), serum sIL-6R levels were measured in 15 RA patients and 15 healthy control subjects using a sandwich enzyme-linked immunosorbent assay. Correlation analysis was performed between sIL-6R levels and clinical variables such as joint score, Lansbury’s index, C-reactive protein and platelet counts. Levels of sIL-6R and IL-6 were also measured in paired samples of serum and synovial fluid obtained at the same time from nine RA patients. Serum sIL-6R levels in RA patients (153.9±56.9 ng/ml) were significantly higher than those of control subjects (115.1±19.1 ng/ml; P<0.05). However, sIL-6R levels did not correlate with any clinical characteristic of RA. sIL-6R was detectable in synovial fluid, but was invariably lower than in serum, in contrast to IL-6 (i.e. much higher in synovial fluid). It correlated neither with total cell nor neutrophil number in synovial fluid. Serum C-reactive protein levels were significantly correlated with IL-6 in synovial fluid, but not with sIL-6R in synovial fluid. These results indicate that serum sIL-6R levels are increased in RA patients. High levels of serum sIL-6R did not seem to be derived from the site of local inflammation. The readily detectable sIL-6R in synovial fluid may co-operate with IL-6 in the pathogenesis of synovitis in RA.     

Soluble interleukin-6 receptor in rheumatoid arthritis

To investigate the pathophysiologic role of soluble interleukin-6 receptor (sIL-6R) in patients with rheumatoid arthritis (RA), serum sIL-6R levels were measured in 15 RA patients and 15 healthy control subjects using a sandwich enzyme-linked immunosorbent assay. Correlation analysis was performed between sIL-6R levels and clinical variables such as joint score, Lansbury’s index, C-reactive protein and platelet counts. Levels of sIL-6R and IL-6 were also measured in paired samples of serum and synovial fluid obtained at the same time from nine RA patients. Serum sIL-6R levels in RA patients (153.9±56.9 ng/ml) were significantly higher than those of control subjects (115.1±19.1 ng/ml;P<0.05). However, sIL-6R levels did not correlate with any clinical characteristic of RA. sIL-6R was detectable in synovial fluid, but was invariably lower than in serum, in contrast to IL-6 (i.e. much higher in synovial fluid). It correlated neither with total cell nor neutrophil number in synovial fluid. Serum C-reactive protein levels were significantly correlated with IL-6 in synovial fluid, but not with sIL-6R in synovial fluid. These results indicate that serum sIL-6R levels are increased in RA patients. High levels of serum sIL-6R did not seem to be derived from the site of local inflammation. The readily detectable sIL-6R in synovial fluid may co-operate with IL-6 in the pathogenesis of synovitis in RA.     

Hyper-interleukin (IL)-6-naemia in haemophagocytic lymphohistiocytosis

Clinical features in patients with haemophagocytic lymphohistiocytosis (HLH) have been demonstrated to be characterized by hypercytokinaemia. Previously, we reported the impact of high serum levels of interferon (IFN)-gamma and soluble IL-2 receptor (sIL-2R) on patient outcome; however, it was not known if serum levels of interleukin (IL)-6 also could be a prognostic factor. In a study during the active phase of disease in 25 cases of HLH in children and young adults (median age 3 years, range 0.1–23 years), we noted 12 cases which showed serum IL-6 >100 (normal <4.0) pg/ml. Five of these cases showed hyper-IL-6-naemia alone without hyper-IFN-gamma-naemia (group A) whereas seven cases showed both hyper-IL-6- and IFN-gamma-naemia (group B). Patient outcome did not differ between the patients with IL-6 >100 pg/ml and those with IL-6 <100 pg/ml, suggesting that high serum concentrations of IL-6 alone do not necessarily indicate poor prognosis in patients with HLH. Among the cases with hyper-IL-6-naemia (>100 pg/ml), underlying disorders causing haemophagocytosis were found to be different between groups A and B.     

Soluble interleukin-6 receptors in inflammatory bowel disease: relation to circulating interleukin-6.

The in vivo appearance of soluble interleukin (IL)-6 receptor (sIL-6R) in serum from patients with inflammatory bowel disease was examined using an enzyme linked immunosorbent assay (ELISA). The serum sIL-6R concentrations in patients with active disease (ulcerative colitis, 148.4 (5.1); Crohn's disease, 142.3 (9.3) ng/ml; mean (SEM)) were significantly raised compared with those in patients with inactive disease (ulcerative colitis, 116.2 (7.2); Crohn's disease, 114.3 (7.1) ng/ml), some other type of colitis (104.8 (11.6) ng/ml), or in normal subjects (107.3 (2.4) ng/ml). These differences were also seen in paired samples examined during both active and inactive phases. Additionally, serum sIL-6R and IL-6 concentrations correlated significantly with C-reactive protein levels in both ulcerative colitis and Crohn's disease patients (r = 0.23 and 0.56, respectively; p < 0.05 for both). Furthermore, gel filtration analysis of serum from these patients showed two major peaks of immunoreactive IL-6-one peak corresponding to free IL-6 and another peak to sIL-6R-bound IL-6-this was further confirmed by a luminescence sandwich ELISA. These results, together with its in vitro effects, indicate that natural sIL-6R may function as a powerful enhancer of the IL-6-dependent immune processes observed in inflammatory bowel disease.     

Serum interleukin-6, soluble interleukin-6 receptor and soluble gp130 exhibit different patterns of age- and menopause-related changes

Growing evidence suggests that interleukin-6 (IL-6) may play a pathogenetic role in postmenopausal bone loss and in other age-related pathological conditions. In this study, we have examined the age-related changes in the serum levels of IL-6 and the soluble receptors that modulate its biological activity--soluble IL-6 receptor (sIL-6R) and soluble gp130 (sgp130)--in 220 women (from 25 to 104yr old), including 22 centenarians. Serum IL-6 rose exponentially with age (r=0.74, p<0.0001). The median level of IL-6 increased almost ten-fold with age, from 1.16pg/ml in premenopausal women to 10.27pg/ml in centenarians. Serum sIL-6R and sgp130 showed an increase until the seventh decade and a progressive decrease in older ages (r=0.39, p<0.0001 and r=0.26, p=0.008, respectively). IL-6, sIL-6R and sgp130 were significantly higher in women within 10yr of menopause as compared to premenopausal subjects (1.51 vs. 1.16pg/ml, p=0.012; 41.9 vs. 35.7ng/ml, p=0.002; and 253.4 vs. 230.7ng/ml, p=0.008, respectively). In postmenopausal women, a negative correlation was found between sIL-6R and the lumbar bone mineral density (BMD) (r=-0.28, p=0.002) even after adjusting for age and weight. Furthermore, sIL-6R levels were higher in osteoporotic compared to normal women (47.9 vs. 39.5ng/ml, p=0.001). In conclusion, our results show that the serum levels of IL-6, sIL-6R and sgp130 exhibit different patterns of age- and menopause-related changes, and that the biological activity of IL-6 may be increased with age with potential implications in the age-related diseases such as osteoporosis.     

Interleukin-6 signalling in juvenile idiopathic arthritis is limited by proteolytically cleaved soluble interleukin-6 receptor

OBJECTIVES: Interleukin-6 (IL-6) exerts multiple effects on chondrocytes and fibroblasts within the joint and is associated with disease activity in juvenile idiopathic arthritis (JIA). Although these cells express the ubiquitous signalling receptor for all IL-6-related cytokines, gp130, they do not express a cognate IL-6 receptor. Consequently, IL-6 responses within these cells occur via IL-6 trans-signalling relying on the presence of a soluble receptor (sIL-6R). Levels of sIL-6R in vivo are governed by either proteolytic cleavage (PC) of cognate receptor or by differential sIL-6R mRNA splicing (DS). The aim of this study was to evaluate the contribution of both isoforms to clinical parameters associated with IL-6 signalling in JIA. METHODS: IL-6, sIL-6R and DS-sIL-6R were measured by ELISA in serum and synovial fluid (SF) samples from 86 JIA patients. These data were related to indicators of inflammation-erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) and compared between patients stratified by subtype, age and disease duration. RESULTS: SF IL-6 significantly correlated with general indicators of activity (ESR and CRP) and SF PC-sIL-6R to a lesser degree with CRP. When the IL-6:sIL-6R ratio was calculated as an indicator of the potential for IL-6 signalling within the joint, 33% of SF samples showed a ratio >1 indicating saturation of sIL-6R by IL-6. Mean DS-sIL-6R levels were 0.71 ng/ml, whereas PC-sIL-6R levels constituted the majority of sIL-6R at 20.89 ng/ml. CONCLUSIONS: IL-6 trans-signalling within the joints of JIA patients is predominantly governed by the presence of PC-sIL-6R, and the data provided suggest that synovial levels of IL-6 and sIL-6R would be sufficient to drive IL-6 responses in chondrocytes and synovial fibroblasts.     

Clodronate treatment reduces serum levels of interleukin-6 soluble receptor in Paget's disease of bone

OBJECTIVE: Interleukin-6 (IL-6) and its soluble receptor (sIL-6R) stimulate osteoclast formation and activity. The primary cell abnormality in Paget's disease of bone (PDB) involves osteoclasts. Pagetic osteoclasts overproduce IL-6 and IL-6 receptor in vitro. In vivo, IL-6 serum levels are very high in the acute phase of PDB. The aim of this study was to evaluate the modification in the serum levels of IL-6, sIL-6R and osteotropic hormones (parathormone, 25OHD3 and 1,25(OH)2D3) as a in long-term response to clodronate treatment in patients with PDB. METHODS: 16 patients (8 females) with polyostotic PDB were studied. IL-6, sIL-6R and osteotropic hormones serum levels were evaluated in active PDB and after clodronate treatment (300 mg injected intravenously for 5 consecutive days). The sequential changes in total alkaline phosphatase (tALP) serum levels were used to assess the maximal pharmacological response to treatment. RESULTS: In untreated pagetic patients, mean serum levels of IL-6 (3.20+/-1.18 pg/ml) and sIL-6R (35.02+/-8.33 ng/ml) were significantly increased. Serum osteotropic hormone levels fell within the normal range. Eight weeks after treatment, the maximal pharmacological response to clodronate was associated with a significant reduction of sIL-6R serum levels in all patients, without a significant variation in serum IL-6 and osteotropic hormone levels. Moreover, we observed a correlation between lower sIL-6R serum levels before clodronate therapy and complete remission of PBD, defined as a decrease of tALP serum levels within the normal range. CONCLUSION: The decrease in serum sIL-6R levels could be one of the molecular mechanisms that play a role in the clinical response to clodronate treatment in PDB.     

Plasma interleukin-2 and a soluble/shed interleukin-2 receptor in serum of patients with Crohn's disease. Effect of cyclosporin.

Circulating concentrations of interleukin-2 (IL-2) and a soluble or shed form of the IL-2 receptor (sIL-2R) were determined by enzyme-linked immunosorbent assays (ELISA) in 61 patients with chronic active Crohn's disease (CD) initially and during a three month placebo controlled trial of cyclosporin 5-7.5 mg/kg/day. The baseline median (25-75% range) plasma IL-2 concentration was 0.6 ng/ml (0.3-2.85 ng/ml) in patients who did not receive prednisolone, 0.5 ng/ml (0.23-3.4 ng/ml) in patients who did (not significant), and 0 ng/ml (0-0.07 ng/ml) in control subjects (p less than 0.00001). The corresponding median serum sIL-2R concentrations were 747 U/ml (580-1287 U/ml), 540 U/ml (422-616 U/ml) respectively in CD patients (p = 0.006) and 320 U/ml (268-406 U/ml) in control subjects (p less than 0.00001). Increased concentrations of plasma IL-2 and serum sIL-2R were seen in 66% and 81% of the patients, respectively. A fall in serum sIL-2R was only seen in patients who improved with cyclosporin treatment (p = 0.006). At month 3 the median serum sIL-2R concentration was 440 U/ml (400-668 U/ml) v 801 U/ml (534-1067 U/ml) in patients not responding to cyclosporin (p = 0.003). No changes occurred in the placebo group. These results suggest that the IL-2 dependent pathway of immune activation is upregulated in vivo in CD and that cyclosporin may interfere with this process.     

High level of soluble interleukin-2 receptor in serum predicts treatment resistance and poor progression-free survival in multiple myeloma

The IL-2/IL-2 receptor (IL-2R) system plays a central role in maintaining normal T cell immunity, and its disturbance is associated with several hematologic disorders. Studies have found in several types of lymphoma that abnormal amounts of soluble IL-2R (sIL-2R) may result in imbalance of the IL-2/IL-2R system and hence of the T cell immunoregulation. Whether the level of sIL-2R in blood could predict treatment outcomes or not needs to be investigated in multiple myeloma (MM) patients. The level of sIL-2R in serum was measured using enzyme-linked immunosorbent assay (ELISA) in 81 patients with newly diagnosed MM. Twenty-six patients (32.1%) were treated with bortezomib-based regimens and 55patients (67.9%) received old drugs-based regimens. The mean concentration of sIL-2R for myeloma patients was 8.51 ng/ml, significantly higher than that of healthy controls (0.56 ng/ml, p < 0.0001). The best cutoff value for sIL-2R in predicting high risk for disease progression is 6.049 ng/ml with an area under curve (AUC) of 0.665 (p = 0.013). Thirty-six patients (44.4%) were classified as higher sIL-2R level group (> 6.049 ng/ml), and 45 patients (55.6%) as lower group (≤ 6.049 ng/ml). The overall response rate (ORR) was 60.0% in lower sIL-2R level group, and 41.7% in higher level group (p = 0.156). The median progression-free survival (PFS) and overall survival (OS) was 12 months (range, 2.0–65 months) and 20 months (range, 2.0–118 months), respectively. In a multivariate survival analysis, including Eastern Cooperative Oncology Group performance status score, treatment response, and sIL-2R level, it was found that all these three parameters were significantly independent prognostic factors for PFS (p = 0.032, 0.016, and 0.043, respectively), but none factors maintained their value in predicting OS. Subgroup analysis revealed that high level of sIL-2R is correlated with significantly inferior PFS in patients treated with bortezomib-based regimens (p = 0.004). Serum sIL-2R level is an independent prognostic factor for PFS, indicating novel drugs targeting the imbalance of IL-2/IL-2R system may be a promising strategy in MM.     

The combination of IL-6 and its soluble receptor is associated with the response of rheumatoid arthritis patients to tocilizumab

BackgroundIL-6 contributes significantly to the chronic inflammatory process of rheumatoid arthritis (RA). Tocilizumab, a humanized anti-human IL-6 receptor antibody that blocks the signaling originated by the IL-6/IL-6R complex, is an effective treatment. However, predictors of the response to tocilizumab are still required. We aimed to combine IL-6 and soluble IL-6R (sIL-6R) levels to identify groups of responses.MethodsHeparinized blood and clinical data from 63 RA patients were collected before treatment and after 3 and 6 months. Two-step clustering (SPSS v.18) was used to establish the relationship between IL-6 and sIL-6R. Then, we compared European League Against Rheumatism (EULAR) response criteria with remission achievement in the groups of patients.ResultsThree statistical significant clusters of RA patients (i.e., g1, g2, and g3) were defined by serum concentrations of IL-6 and sIL-6R at baseline. All groups of RA patients had higher IL-6 and sIL-6R levels than healthy donors. The levels of IL-6 expressed as median (IQR) in g1 patients were 124(90–183) pg/ml, in g2 12.3(4.4–24) pg/ml, and in g3 60.1(30–146) pg/ml (p < 0.001). The levels of sIL-6R expressed as mean ± sd in g1 patients were 250.5 ± 72 ng/ml, in g2 269.1 ± 125 ng/ml, and in g3 732.7 ± 243 ng/ml (p < 0.001). Disease activity score (DAS)28, C-reactive protein, and erythrocyte sedimentation rate were comparable in the three groups at baseline. Disease duration in g3 was the longest (median(IQR) years: g1 = 11(5–15), g2 = 12(8–20), and g3 23(16–26); p = 0.006), with years of disease evolution being correlated with sIL-6R levels (R = 0.417, p < 0.001). Simple and Clinical Disease Activity Index (SDAI and CDAI) decreased significantly in the three groups. However, EULAR response criteria and remission achievement at 6 m was different in the three groups (p = 0.03 and 0.04, respectively). In all. 17 out of the 18 patients in g1 had a good or moderate response to tocilizumab. Conversely, the percentage of patients with no response to tocilizumab was higher in g3 than in g1 and g2. We also observed different changing patterns of IL-6 and sIL-6R levels among the three groups.ConclusionsRA patients could be easily stratified prior to therapeutic intervention with two molecules related to the pathway blocked by tocilizumab. G1 patients, who had the best response to tocilizumab, had the highest level of IL-6 and the lowest level of sIL-6R.     

Detection of membrane and soluble interleukin-6 receptor in lymphoid malignancies

Summary. We studied the membrane expression of the gp80 chain of IL-6 receptor (IL-6R) by quantitative flow cytometry in chronic lymphocytic leukaemia (CLL) and leukaemic centrocytic lymphoma using a panel of seven monoclonal antibodies. IL-6R was detected in 18/26 CLL cases and 4/7 lymphoma cases, with a mean antigen density <3000 molecules/cell. Multiple labelling experiments confirmed the IL-6R expression by neoplastic cells. Specific mRNA was found by RT-PCR in neoplastic cells. A specific ELISA test was designed using two anti-IL-6 receptor MAbs to measure the serum soluble IL-6R (sIL-6R) in CLL (n = 48), B-cell non-Hodgkin's lymphoma (NHL; n = 40), and monoclonal gammopathy (MG; n = 32). SIL-6R was higher in CLL (170±12.6ng/ml) in NHL (160 ± 12ng/ml) and MG patients (183±23ng/ml) than in age-matched controls (100 ±5.6 ng/ml; P < 0.001) and higher in high-grade than low-grade NHL. No correlation was noted with a previous treatment. Among CLL cases the patients classified as stage B according to the Binet's staging of the disease had the highest sIL-6R values, thus suggesting a link with tumour cell mass.     

Changes of IL-6 and relevant cytokines in patients with hepatocellularcarcinoma and their clinical significance

AIM To study the changes of IL-6,IL-2, sIL-2R and TNF ir patients with hepatocellular carcinoma(HCC)and their clinical significance.METHODS IL-6, IL-2, sIL-2R and TNF were detected by avidin-biotin-system ELISA, double-sandwichELISA respectively in 60 patients with HCC and 36 patients with liver cirrhosis (LC) and 66 healthy persons.RESULTS The levels of IL-6, sIL-2R and TNF increased, but IL-2 level was lower in patients with HCCthan that in normal controls (NC) (t test, t=8.21, 4.71, 3.87, 2.13, P<0.01 or 0.05). IL-6 level in HCCwas 10 fold higher than NC, and also much higher than LC. IL-6 level was higher in later stage than that inearlier stage. There was a positive correlation between IL-6 and sIL-2R, TNF, while no positive correlationwas found between IL-2 and IL-6, sIL-2R in HCC.CONCLUSION The remarkably higher level of IL-6 is helpful for the early diagnosis of HCC.     

Incidence of apoptosis and cell proliferation in multiple myeloma: correlation with bcl-2 protein expression and serum levels of interleukin-6 (IL-6) and soluble IL-6 receptor

We evaluated the in vivo incidence of apoptosis and cell proliferation in multiple myeloma (MM) and investigated the correlation of both cellular events with histological tumour stage and grade, bcl-2 protein expression, serum IL-6 and sIL-6R. MATERIAL AND METHODS: The TUNEL method was used to assess apoptosis and immunohistochemistry to assess the expression of proliferating cell nuclear antigen (PCNA) and bcl-2 protein in 30 bone marrow biopsy specimens. The apoptotic index (AI) and proliferative index (PI) were defined as the percentage of TUNEL and PCNA positive plasma cells, respectively. RESULTS: The mean AI was 0.162% and the mean PI 27.44%. A positive correlation between AI and PI was found (r = 0.44, P = 0.017). PI was also correlated with tumour grade (P = 0.015). The mean bcl-2 protein expression was 70% and did not correlate with AI or PI, but was higher in specimens taken at first diagnosis than in specimens taken after response to treatment (P = 0.035). The mean serum IL-6 and sIL-6R values were 9.43 pg mL-1 and 47.27 ng mL-1, respectively. These parameters did not correlate with AI or PI. CONCLUSIONS: The results indicate that MM might be among the malignancies with very low incidence of apoptosis. Proliferative activity increased in parallel with tumour histological grade. A positive correlation between apoptosis and proliferation was observed, but the incidence of these two cellular events seems not to be related to the bcl-2 protein expression and the serum levels of IL-6 and sIL-6R.     

Human myeloma cells shed the interleukin-6 receptor: inhibition by tissue inhibitor of metalloproteinase-3 and a hydroxamate-based metalloproteinase inhibitor

Interleukin-6 (IL-6) is the major growth factor for human myeloma cells, exerting its effect through the IL-6 receptor (IL-6R). A soluble form of IL-6R (sIL-6R) has been identified, which increases the sensitivity of myeloma cells to IL-6. In patients with multiple myeloma (MM), serum concentrations of sIL-6R are elevated and associated with poor prognosis. The present study was undertaken to determine whether proteolytic cleavage of IL-6R could contribute to sIL-6R release from human myeloma cells, and also to identify the class of proteinase responsible for this event. Human myeloma cell lines were shown to express IL-6R upon their surface and also to release sIL-6R into culture supernatants. In addition, phorbol 12-myristate 13-acetate (PMA) stimulated a loss of IL-6R from the cell surface, with a corresponding increase in the concentration of sIL-6R in the supernatant. Inhibitors of serine and cysteine proteinases, and tissue inhibitor of metalloproteinase (TIMP) -1 and TIMP-2, were shown to have no effect on the magnitude of sIL-6R release. In contrast, TIMP-3 and a hydroxamate-based metalloproteinase inhibitor (BB-94), inhibited both constitutive and PMA-induced release of sIL-6R. Myeloma cells freshly isolated from the bone marrow of a patient with MM were also shown to express IL-6R upon their surface, and to shed this receptor in response to PMA. These data demonstrate that increased proteolytic cleavage of IL-6R, mediated by a non-matrix-type metalloproteinase, is likely to contribute to the elevated concentrations of sIL-6R found in the serum of patients with MM. Inhibition of sIL-6R release by hydroxamate-based metalloproteinase inhibitors may represent a novel therapeutic approach to the treatment of MM.     

Malignancy: Identification of Predictors of Disease Status and Progression in Patients with Myeloma (MM)

Multiple studies have attempted to recognize the best markers of disease activity and outcome in myeloma (MM). Our objective was to identify the best variables that can reflect MM disease status. Design and methods: The data obtained from all the following tests were included in the analysis: serum levels of the 2 growth factors known to be crucial for MM growth (i.e. IL-6, and sIL-6R), routine peripheral blood data (Hb%, serum calcium, albumin, CRP, B2m, LDH) and bone marrow plasma cell (BMPC)%, as well as the age and sex of patients. The study was conducted on 21 cases of MM under chemotherapy (aged 48-74 years; M/F = 13/8) and 12 matched normal individuals. The patients were categorized into 2 groups according to their clinical status: Group#1 (n = 16; cases in plateau/stable phase), and Group#2 (n = 5; advanced/refractory cases). Results: Student t-test confirms that serum IL-6 and sIL-6R are the most statistically different variables upon comparing cases in plateau phase (Group#1) with those of advanced disease (Group#2). Stepwise discriminant analysis of data has resulted in a function that is composed of the 2 most salient variables (i.e. serum IL-6, sIL-6R). The proposed function was highly significant (p = 0.0000) with Wilk's Lambda = 0.02538. The diagnostic capability of the proposed function was very high (percent of grouped cases that were classified correctly= 100%). Conclusion: measurement of serum IL-6 and sIL-6R gives the best prediction of disease activity in patients with MM.     

Effect of cyclosporin A on interleukin-6 and soluble interleukin-2 receptor in patients with rheumatoid arthritis.

OBJECTIVE--To investigate the effect of cyclosporin A (CyA) therapy on circulating concentrations of interleukin-6 (IL-6) and soluble interleukin-2 receptor (sIL-2R) in patients with rheumatoid arthritis (RA). METHODS--Twenty four RA patients with active disease were studied. Plasma was collected before and after 16 weeks of CyA treatment. IL-6 was measured by B9 bioassay and sIL-2R by enzyme linked immunosorbent assay (ELISA). RESULTS--The initial median IL-6 concentration of 165 IU/ml decreased significantly to 71 IU/ml after 16 weeks (p < 0.05). Similarly, the initial median plasma sIL-2R value of 665 U/ml decreased significantly to 570 U/ml (p < 0.05). This decrease was accompanied by an improvement in clinical parameters of disease activity. Some association between sIL-2R, IL-6, haemoglobin, and platelets was also observed. CONCLUSIONS--This study has demonstrated that, in vivo, CyA therapy in RA can significantly reduce circulating concentrations of IL-6 and sIL-2R. Modulation of both T and non-T cell derived cytokines may be one mechanism by which CyA improves rheumatoid disease. Whether this is a direct effect of CyA on the cells within the rheumatoid joint producing these cytokines or an indirect effect mediated by other cytokines which can influence IL-6 and Il-2R values remains to be determined.     

Interleukin-6, soluble interleukin-2 receptor and soluble interleukin-6 receptor in the sera of patients with different histological patterns of rheumatoid synovitis

OBJECTIVE: The present study was conducted to investigate whether the serum levels of interleukin 6 (IL-6), soluble IL-2 receptor (sIL-2R) and sIL-6R are associated with the morphological appearance of rheumatoid arthritis (RA). METHODS: Using the ELISA technique we measured the IL-6, sIL-2R and sIL-6R concentrations in the serum of 34 patients with RA and 28 patients with osteoarthritis (OA). Histological analysis of synovial samples distinguished 2 types of rheumatoid synovitis. Twenty-one RA specimens presented diffuse infiltrates of mononuclear cells without any specific microanatomical organization. In remaining 13 samples the formation of lymphocytic follicles with germinal center-like structures was found. RESULTS: Serum levels of IL-6, sIL-2R and sIL-6R were elevated in patients with RA compared to the OA control group (p < 0.001, p < 0.001 and p < 0.05 respectively). Concentrations of IL-6 and sIL-2R were highest in the serum of RA patients with follicular synovitis in comparison to patients with diffuse synovitis (p < 0.001 and p < 0.01 respectively) and could distinguish RA patients with these two histological variants of the disease. Serum levels of IL-6 and sIL-2R correlated with markers of disease activity such as ESR and CRP levels. In addition, the clinical data suggest a more severe disease among RA patients with follicular synovitis. CONCLUSION: Distinct histological types of rheumatoid synovitis associated with unique serum concentrations of IL-6 and sIL-2R reflect levels of disease activity and confirm the concept of RA heterogeneity.