Lack of changes in soluble interleukin-2 receptor serum levels during chemotherapy-induced lymphocyte damage

The biological significance of soluble IL-2 receptors (sIL-2R) is still unknown; in particular, it is not yet clear whether their increase in the blood may reflect activation of immune cells, or whether it is related to an immune dysfunction. To investigate this problem, we evaluated serum levels of sIL-2R before and after administration of a highly lymphocytolitic chemotherapy (FEC: fluorouracil, epirubicin, cyclophosphamide) in a group of 6 patients with advanced breast cancer. SIL-2R were analyzed in relation to lymphocyte number. Absolute mean number of lymphocytes was significantly lower after than before chemotherapy. On the contrary, no significant difference was seen in sIL-2R mean levels, and no significant correlation was observed between changes in sIL-2R and in lymphocyte number following chemotherapy. These results would exclude that sIL-2R may simply be due to a passive release following lymphocytic damage.     

Elevation of soluble interleukin-2 receptor levels in nasal allergy

To investigate soluble IL-2 receptor (sIL-2R) levels in nasal allergy, the sera and nasal secretions from patients with nasal allergy and from healthy subjects were subjected to a double-epitope enzyme-linked immunosorbent assay. Significant elevation of sIL-2R concentrations in the sera and nasal secretions was observed in the allergy patients (n = 26) compared with those of healthy subjects (n = 9). IL-2R-positive (CD25(+)) cells were observed in the crust formed in an allergic nasal mucosa. The concentration of sIL-2R in the sera correlated neither with the eosinophil count of the peripheral blood count nor with clinical severity. The concentration of sIL-2R in the nasal secretions was significantly higher compared with that in the sera from allergic patients (p < 0.01), whereas no significant difference was observed between sIL-2R levels in the sera and nasal sections from normal subjects. These findings indicate that sIL-2R plays an essential role in allergic processes by regulating IL-2R-positive cells recruited into the nasal mucosa.     

Modulation of circulating leptin levels by its soluble receptor

Leptin is an adipocyte-derived hormone with potent weight reducing effects. Genetically obese rodents with mutations of leptin or the leptin receptor are defective in leptin signaling and develop morbid obesity and diabetes. Interestingly, the levels of both leptin mRNA and protein are increased by up to 20-fold in these animals, suggesting the existence of a feedback mechanism controlling the amount of leptin in circulation. In this report, we attempted to determine whether the up-regulation of circulating leptin in Zucker Diabetic Fatty rats, which are nonresponsive to leptin due to a receptor point mutation, is entirely due to increased expression of leptin. We demonstrate that the high level of circulating leptin in these rats is attributable to at least two factors: increased leptin expression by the adipose tissue and delayed clearance of leptin from circulation due to binding to its soluble receptor. The latter conclusion was supported by three lines of evidence: 1) The soluble leptin receptor is up-regulated by about 20-fold in Zucker Diabetic Fatty rats; 2) Adenovirus-mediated overexpression of the soluble leptin receptor results in a similar -fold increase of circulating leptin; 3) In ob/ob mice, which have no endogenous leptin, exogenously administered leptin reaches a higher level when the soluble leptin receptor is overexpressed. The weight-reducing effect of leptin is enhanced in C57Bl/6 ob/ob mice with overexpression of the soluble leptin receptor. Soluble leptin receptor may be a significant factor determining the amount of total leptin in circulation.     

White matter lesions and soluble interleukin-1 receptor type II in CSF from demented and non-demented subjects

White matter lesions (WMLs) in the brain is a common, unspecific finding on magnetic resonance imaging appearing both in the healthy elderly as well as in a number of different diseases including dementia disorders. However, the pathophysiological and clinical significance of WMLs in dementia disorders is still unknown. In this study, we investigated the possibility of their origin being inflammatory by studying the correlation between WMLs and cerebrospinal fluid (CSF) levels of the proinflammatory cytokine soluble interleukin-1 receptor type II (sIL-1RII). The sIL-1RII is a member of the IL-1 family, and has been found to be elevated in CSF from Alzheimer's disease (AD) patients. In the present study, two groups of patients complaining of memory disturbances with little or extensive WMLs respectively, were examined, as well as healthy subjects. In accordance with other reports, WML scores (total, periventricular as well as deep lesions) were positively correlated with age but not mini mental state examination (MMSE) scores, and were significantly higher in patients with a dementia diagnosis as compared to non-demented subjects. There were no differences in sIL-1RII levels in CSF regardless of amount of total, periventricular or deep WMLs, nor were there any differences between demented and non-demented subjects. In conclusion, sIL-1RII levels in CSF are not correlated to magnetic resonance imaging WMLs in patients with dementia disorders or in healthy subjects.     

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.     

Interleukin-1 receptor antagonist competitively inhibits the binding of interleukin-1 to the type II interleukin-1 receptor.

The interleukin-1 receptor antagonist (IL-1ra) inhibits the binding of interleukin-1 (IL-1) to T-cell lines possessing the type I IL-1 receptor; evidence has been published (Carter, D. B., Deibel, M. R. J., Dunn, C. J., Tomich, C. S., Laborde, A. L., Slightom, J. L., Berger, A. E., Bienkowski, M. J., Sun, F. F., McEwan, R. N., Harris, P. K. W., Yem, A. W., Waszak, G. A., Chosay, J. G., Sieu, L. C., Hardee, M. M., Zurcher-Neely, H. A., Reardon, I. M., Heinrickson, R. L., Truesdell, S. E., Shelly, J. A., Eessalu, T. E., Taylor, B. M., and Tracey, D. E. (1990) Nature 344, 633-638; Hannum, C. H., Wilcox, C. J., Arend, W. P., Joslin, F. G., Dripps, D. J., Heimdal, P. L., Armes, L. G., Sommer, A., Eisenberg, S. P., and Thompson, R. C. (1990) Nature 343, 336-340) that IL-Ira does not bind to the type II IL-1 receptor (IL-1RtII). In this study we examined the ability of human recombinant IL-1ra to block the binding of IL-1 to the IL-1RtII on human polymorphonuclear leukocytes (PMN) and Raji human B-lymphoma cells. The binding of 125I-IL-1 beta to PMN was competively inhibited by IL-1ra. IL-1 beta was more potent in inhibiting the binding of 125I-IL-1 beta than IL-1ra. Incubating PMN with 125I-IL-1ra in the presence of increasing concentrations of IL-1 beta or IL-1ra showed that IL-1 beta was an approximately 40-fold more potent inhibitor of binding of 125I-IL-1ra than unlabeled IL-1ra. The IL-1ra was approximately 500-fold less potent in inhibiting the binding of 125I-IL-1 alpha than IL-1 alpha. IL-1ra was also able to competitively inhibit binding of 125I-IL-1 beta to Raji cells. PMN or Raji cells were also incubated with 125I-IL-1 in the absence or presence of IL-1 or IL-1ra. After cross-linking of IL-1 to cells followed by specific immunoprecipitation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a band at 85 kDa corresponding to the 68-kDa IL-1RtII. However, in the presence of an excess of either unlabeled IL-1 or IL-1ra, the 85-kDa IL-1.IL-1RtII complex was not present. These findings demonstrate that the IL-1ra recognizes and blocks IL-1 binding to the IL-1RtII.     

Dynamic changes in soluble interleukin-2 receptor levels during treatment of Graves' disease. Correlation with disease activity

The activation of T lymphocyte is accompanied by the release of soluble interleukin-2 receptors (sIL-2R) which can be assessed in biological fluids. A prospective study of the dynamic changes in sIL-2R levels was performed in the serum of 10 patients undergoing a medical treatment for Graves' disease. All patients received carbimazole during the study and, when necessary, L-thyroxine to compensate hypothyroidism. sIL-2R levels were measured before (M0) and after the 1st (M1), 3rd (M3) and 6th month (M6) of treatment. The levels of sIL-2R were high at M0 and M1, and decreased significantly between M1 and M3 (p = 0.03). At M0, the levels of sIL-2R were highly correlated with triiodothyronine (T3) levels (p = 0.0003), early [131I] uptake (p = 0.007) and, to a lesser degree, with anti-thyrotropin receptor antibody levels (p = 0.02). At M6, no correlation was found anymore. We conclude that sIL-2R levels are increased in patients with untreated Graves' disease. They are highly correlated with the markers of Graves' disease activity and decrease during medical treatment.     

Identification of soluble interleukin-1 binding protein in cell-free supernatants. Evidence for soluble interleukin-1 receptor

This study describes the identification and characterization of a soluble interleukin-1 (IL-1) binding protein in the conditioned media from Raji human B-lymphoma cells. The soluble IL-1 binding material was isolated by IL-1 affinity chromatography, and treatment with trypsin decreased its ability to bind to IL-1 demonstrating its protein nature. The soluble IL-1 binding protein was specific for IL-1 and was able to discriminate between Il-1 alpha and IL-1 beta in a manner analogous to the membrane-bound Raji IL-1 receptor. The specificity of the IL-1 binding protein was further established in two ways. 1) Cell-free supernatants from Raji "receptor-negative" cells did not contain any IL-1 binding protein, thus ruling out nonspecific interactions between IL-1 and a serum or other protein present in the conditioned medium; and 2) the soluble binding protein inhibited IL-1 binding to Raji cells in a dose-dependent manner. Scatchard analysis of IL-1 beta binding showed the dissociation constant (KD) to be 5.1 nM for the soluble IL-1 binding protein compared with 0.8 nM for the membrane-bound IL-1 receptor. Gel chromatography of the soluble binding protein yielded a major peak of IL-1 binding activity with a molecular mass of 35-45 kDa. The characteristics of the soluble IL-1 binding protein described above are consistent with those of the extracellular binding domain of the membrane-bound Raji IL-1 receptor.     

Serum levels of soluble interleukin-2 receptor (sIL-2R) in B-chronic lymphocytic leukemia.

By using an enzyme-linked immunosorbent assay, the levels of the soluble form of the interleukin-2 receptor (sIL-2R) were evaluated in the peripheral blood of 20 patients with cell chronic lymphocytic leukemia in different stages of disease and in supernatants obtained from enriched B cell suspensions. In either all serum samples or in one out of three supernatants, elevated levels of sIL-2R were found. This could indicate that the B leukemic cells release sIL-2R which in turn, for its potential capacity of binding circulating IL-2, could contribute to the abnormal immunoregulation which characterizes B-CLL. This finding, which needs further investigation, could have prognostic significance.     

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.     

Interleukin-1 receptor antagonist binds to the type II interleukin-1 receptor on B cells and neutrophils.

We have examined the binding of human and rodent interleukin-1 receptor antagonist (IL-1ra) to the type II IL-1 receptor on the human B cell line, Raji, on the mouse pre-B cell line, 70Z/3, and on human polymorphonuclear leukocytes (PMNs). Human IL-1ra binds to the receptors on the human B cells with an affinity (KD = 15 +/- 3 nM) equal to that of IL-1 alpha and only 15-fold lower than that of IL-1 beta and, likewise, binds to human PMNs with an affinity (KD = 8 +/- 4 nM) 15-fold lower than that of IL-1 beta. Mouse and rat IL-1ra bind to these two human cell types with an affinity similar to that of the human protein. Human IL-1ra binds very weakly to the type II receptor on the mouse pre-B cells with an affinity (KD = 1.4 +/- 0.2 microM) about 1500-fold lower than human IL-1 beta. Mouse and rat IL-1ra also bind to the mouse pre-B cells with low affinity. The weak binding of the three IL-1ra proteins to these mouse cells appears to be more a consequence of the cell type rather than species specificity. There may be a population of cells for which the actions of IL-1 cannot be effectively opposed by IL-1ra, although this group does not include mature B cells and PMNs.     

Interleukin-1 receptor antagonist, soluble tumor necrosis factor-alpha receptor type I and II, and soluble E-selectin serum levels in multiple sclerosis patients receiving weekly intramuscular injections of interferon-beta1a

BACKGROUND: interferon beta (IFN-beta) reduces relapse rate and disease progression in patients with the relapsing-remitting form of multiple sclerosis (RRMS). IFN-beta may act by upregulating the expression of anti-inflammatory components of the immune system. OBJECTIVES: To determine whether weekly intramuscular (i.m.) injection of IFN-beta1a had a short- or long-term effect on the expression of naturally occurring soluble factors that play an immunosuppressive role within the cytokine network. MATERIALS AND METHODS: serum levels of interleukin-1 receptor antagonist (IL-1Ra), soluble tumor necrosis factor alpha receptor type I and type II (sTNF-alphaRI and sTNF-alphaRII), and soluble E-selectin (sE-Sel) were followed over time in ten patients with RRMS who were treated with weekly i.m. injections of 30 mg (= 6 MU) of IFN-beta1a. Patient sera were sampled before, and 24, 48, 72, 96, and 168 hours after the first IFN-beta1a injection (short-term), and then at 1, 3, 6, 9 and 12 months after therapy initiation (long-term); highly sensitive, commercially available ELISA tests were used. RESULTS: serum levels of IL-1Ra, sTNF-alphaRI and sTNF-alphaRII, but not sE-Sel were significantly increased in both short- and long-term follow-up. Interestingly, IL-1Ra, sTNF-alphaRI and sTNF-alphaRII behaviors were completely different, suggesting that these naturally occurring immunoregulatory factors were differentially affected by IFN-beta1a. CONCLUSION: our study demonstrates that weekly i.m. injection of 30 mg of IFN-beta1a induces the expression of soluble mediators that may suppress the activities of pro-inflammatory cytokines such as IL-1 and TNF-alpha.     

Increased levels of soluble interleukin-6 receptor and CCL3 in COPD sputum

Background

COPD patients have increased numbers of macrophages and neutrophils in the lungs. Interleukin-6 (IL-6) trans-signaling via its soluble receptor sIL-6R, governs the influx of innate immune cells to inflammatory foci through regulation of the chemokine CCL3. We hypothesized that there would be enhanced levels of IL-6, sIL-6R and CCL3 in COPD sputum.

Methods

59 COPD patients, 15 HNS and 15 S underwent sputum induction and processing with phosphate buffered saline to obtain supernatants for IL-6, sIL-6R and CCL3 analysis. Cytoslides were produced for differential cell counting and immunocytochemistry (COPD; n = 3) to determine cell type surface expression of the CCL3 receptors CCR5 and CCR1.

Results

COPD patients expressed higher levels (p < 0.05) of sIL-6R and CCL3 compared to controls (sIL-6R medians pg/ml: COPD 166.4 vs S 101.1 vs HNS 96.4; CCL3 medians pg/ml: COPD 117.9 vs S 0 vs HNS 2.7). COPD sIL-6R levels were significantly correlated with sputum neutrophil (r = 0.5, p < 0.0001) and macrophage (r = 0.3, p = 0.01) counts. Immunocytochemical analysis revealed that CCR5 and CCR1 were exclusively expressed on airway macrophages.

Conclusion

Enhanced airway generation of sIL-6R may promote IL-6 trans-signaling in COPD. Associated upregulation of CCL3 may facilitate the recruitment of macrophages into the airways by ligation of CCR1 and CCR5.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0103-4) contains supplementary material, which is available to authorized users.     

High altitude increases circulating interleukin-6, interleukin-1 receptor antagonist and C-reactive protein

Hypoxic pulmonary vasoconstriction is associated with but may not be sufficient for the development of high-altitude pulmonary oedema (HAPO). Hypoxia is known to induce an inflammatory response in immune cells and endothelial cells. It has been speculated that hypoxia-induced inflammatory cytokines at high altitude may contribute to the development of HAPO by causing capillary leakage in the lung. We were interested if such an inflammatory response, possibly involved in a later development of HAPO, is detectable at high altitude in individuals without HAPO. We examined the plasma levels of interleukin 6 (IL-6), interleukin 1 receptor antagonist (IL-1ra) and C-reactive protein (CRP) in two independent studies: study A, Jungfraujoch, Switzerland, three overnight stays at 3458 m, n=12; study B: Capanna Regina Margherita, Italy, 3 overnight stays at 3647 m and one overnight stay at 4559 m, n=10. In both studies, probands showed symptoms of acute mountain sickness but no signs of HAPO. At the Jungfraujoch, IL-6 increased from 0.1+/-0.03 pg/ml to 2. 0+/-0.5 pg/ml (day 2, P=0.03), IL-1ra from 101+/-21 to 284+/-73 pg/ml (day 2, P=0.01), and CRP from 1.0+/-0.4 to 5.8+/-1.5 micrograms/ml (day 4, P=0.01). At the Capanna Margherita, IL-6 increased from 0. 5+/-0.2 pg/ml to 2.0+/-0.8 pg/ml (P=0.02), IL-1ra from 118+/-25 to 213+/-28 pg/ml (P=0.02), and CRP from 0.4+/-0.03 to 3.5+/-1.1 micrograms/ml (P=0.03). IL-8 was below the detection limit of the ELISA (<25 pg/ml) in both studies. The increase of IL-6 and IL-1ra in response to high altitude was delayed and preceded the increase of CRP. We conclude that: (1) circulating IL-6, IL-1ra and CRP are upregulated in response to hypobaric hypoxic conditions at high altitude, and (2) the moderate systemic increase of these inflammatory markers may reflect considerable local inflammation. The existence and the kinetics of high altitude-induced cytokines found in this study support the hypothesis that inflammation is involved in the development of HAPO.     

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.