Interleukin 1 inhibitory activity secreted by a human myelomonocytic cell line (M20)

The effects of early and late administration of M-20 derived interleukin-1 inhibitor on experimental systemic lupus erythematosus

M-20 interleukin-1 inhibitor is produced by a myelomonocytic cell line. The effects of this molecule, mediated via IL-1 inhibition, include decreased proliferative responses of mouse thymocytes, human T-cells and fibroblasts and reduction in parameters of acute inflammation. Previously, we have demonstrated the emergence of a disease resembling systemic lupus erythematosus (SLE) in naive mice immunized with anti-DNA antibodies carrying different pathogenic idiotypes. The disease was manifested by increased titers of various mouse antibodies, concomitant with the appearance of elevated erythrocyte sedimentation rate (ESR), proteinuria and leukopenia. We have applied this model of experimental SLE (immunized with MIV-7, a human monoclonal antibody) to evaluate the influence of M-20 IL-1 inhibitor, administered at different stages (2 weeks before, 1 month and 3 months following immunization) for a period of 2 weeks, on the findings of the disease in mice. It was shown that M-20 IL-1 inhibitor given 2 weeks prior to the immunization resulted in suppression of the disease induction as documented by lower antibody titer level (30%-50% in the immunized mice as compared with controls). Furthermore, reduced autoantibody levels were accompanied by other beneficial findings consisting of lower ESR, less severe proteinuria and elevated leukocyte counts. No beneficial effects of M-20 IL-1 inhibitor were observed when the agent was administered 1 or 3 months following immunization. We conclude that M-20 IL-1 inhibitor has a favorable effect on experimental SLE in mice, provided it is administered before induction of the disease.

Release of anti-inflammatory mediators after mechanical trauma correlates with severity of injury and clinical outcome

Excessive synthesis of proinflammatory cytokines [tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta] after trauma has been correlated with poor outcome. Recently, naturally occurring inhibitors of TNF-alpha and IL-1 beta have been characterized such as soluble TNF receptors (sTNFRs) and IL-1 receptor antagonist (IL-1ra). The present study was undertaken to determine whether injury results in a rise of circulating sTNFRs and IL-1ra. If so, whether plasma levels of these anti-inflammatory mediators correlate with severity of injury and clinical outcome of these patients. Injured patients (n = 213) showed significantly increased sTNFR and IL-1ra plasma levels throughout the observation period of 14 days, compared with healthy volunteers (n = 127). Patients with severe injury (Injury Severity Score > 16 points) revealed higher levels (p < 0.05) of sTNFRs and IL-1ra than patients with minor trauma (Injury Severity Score < or = 16 points). Patients who died from injury demonstrated increased (p < 0.05) sTNFR p55 and IL-1ra plasma levels, compared with survivors. Thus, anti-inflammatory mechanisms are activated after trauma dependent on severity of injury. Because increased plasma levels of anti-inflammatory reacting proteins portended poorly for patient survival, these mediators may contribute to prediction of outcome after severe injury.

Interleukin-1 and its inhibitors: implications for disease biology and therapy

IL-1 alpha and IL-1 beta are polypeptide hormones that exhibit a broad spectrum of beneficial and harmful biologic activities. Clinical trials designed to benefit from its stimulatory effects on human hematopoiesis and from its role in improving host defenses, are being currently conducted. Other in vivo studies, using IL-1 inhibitors with an attempts to block the detrimental effects of IL-1, are underway. Because of the multifunctional effects of IL-1 in human physiology and its pathogenetic role in several diseases, the capability to control the effects of IL-1 may prove to be a useful tool in medical practice.

The effect of human myelomonocytic leukemic cell line (M20) derived IL-1 inhibitor on human erythroid cell development

The effect of an inhibitor of IL-1, purified from a human myelomonocytic cell line (M20) on the development of human erythroid cell development was studied. The inhibitor, is a protein of 52 kD molecular weight that is distinct immunologically and functionally from other reported IL-1 inhibitors. The experiments were performed in a two-phase culture system that allows separation of the erythroid cell development into an erythropoietin (EPO)-independent phase, where early erythroid-committed BFUe proliferate and differentiate into the more mature progenitors, CFUe, and EPO-dependent phase, where CFUe further proliferate and mature into hemoglobin-containing orthochromatic normoblasts. The results indicated that in both developmental stages the M20-derived inhibitor reversibly blocked cell proliferation without interfering with cell differentiation.

Blocking interleukin-1 receptors

During inflammation, injury, immunological challenge or infection, interleukin-1 appears to mediate, in part, the pathogenesis, of disease. Most studies on interleukin-1 are derived from experiments in which bacterial products, such as endotoxins from Gram-negative bacteria or exotoxins from Gram-positive organisms, are used to stimulate macrophagic cells. In general, several cytokines are induced by microbes to their products. Although cytokines are thought to play a role in the outcome of disease, only a few have been directly implicated as mediators of the pathogenic mechanisms of the host. Studies on specific inhibition of interleukin-1 activity have employed interleukin-1 receptor antagonist, interleukin-1 receptor blocking antibodies or soluble interleukin-1 receptors. Experiments in vitro, in animal models of disease and in human subjects have shed considerable light on a critical role for interleukin-1 in the pathogenesis of disease. This review focuses on interleukin-1 as a cytokine of strategic importance to the outcome of disease, particularly inflammatory and infectious diseases.

Interleukin-1 favours the in vitro development of type 2 T helper (Th2) human T-cell clones

The effects exerted by interleukin-1 (IL1) on the growth and differentiation of human Th1 and Th2 cells were examined. Neither IL1 nor the IL1 receptor antagonist (IL1ra) had detectable activity toward the antigen- or anti-CD3 antibody-induced proliferative response of already established type 1 T helper (Th1) or type 2 T helper (Th2) clones. Moreover, neither exogenous IL1 addiction to, nor neutralization of, endogenously produced IL1 in bulk cultures before cloning changed the Th1-like cytokine profile of PPD-specific T-cell lines. Likewise, IL1 addition in bulk culture before cloning did not significantly affect the Th2-like cytokine profile of Der.p.I-specific T-cell lines (Dermatophagoides pteronyssinus group I). However, Der.p.I-specific T-cell lines, derived in the presence of anti-IL1 Ab, IL1ra or the M-20 IL1 inhibitor, exhibited the reduced ability to produce IL4 and an increased ability to produce interferon gamma (IFN gamma). More importantly, Der.p.I-specific T-cell lines derived in the presence of IL1ra developed into Der.p.I-specific CD4+ T-cell clones showing a Th0/Th1-like, instead of a Th0/Th2-like, cytokine profile. These data suggest that IL1 is not required for the growth of already established human Th1 or Th2 CD4+ T-cell clones and has no regulatory effects on the in vitro development of Th1-like cells, but it plays a critical role in the development of Th2-like cells.

In vivo anti-inflammatory effects of the M20 IL-1 inhibitor: II. Effects on serum reactants

We have previously described an IL-1 Inhibitor derived from the M20 myelomoncytic cell line. This line also secretes several molecules of IL-1. We have shown that this factor is specific to IL-1 in vitro, as well as in vivo. In vitro IL-1 induced proliferative responses of mouse thymocytes, human T cells and fibroblasts and IL-1 stimulated PGE2 secretion from fibroblasts, were all inhibited by the M20 IL-1 Inhibitor. In vivo, the IL-1 Inhibitor reduced parameters of acute inflammation such as fever, leukocytosis and local inflammation. This study describes additional effects of the M20 IL-1 Inhibitor on inflammatory serum reactants. Levels of corticosterone and fibrinogen were increased by injection of IL-1, and decreased by the IL-1 Inhibitor. IL-1 reduced zinc and iron plasma levels and elevated copper plasma levels. The M20 IL-1 Inhibitor reversed these changes in a dose dependent manner. Similar effects produced by IL-6 and TNF were unaffected by the M20 IL-1 Inhibitor. Our results indicate that the M20 IL-1 Inhibitor acts specifically on IL-1 induced responses in vivo. Therefore we conclude that this IL-1 Inhibitor has a great potential as an anti-inflammatory agent.

In vivo anti inflammatory effects of the M20 IL-1 inhibitor: I. Effects on acute inflammatory parameters

Previous studies have described an IL-1 Inhibitor produced by a myelomonocytic line developed in our laboratory (Eur J Immunol 1986; 16: 1449). This IL-1 Inhibitor was secreted by the M20 line constitutively in addition to IL-1, from which it could be separated. We have recently shown that the M20 IL-1 Inhibitor is distinct from the IL-1ra. In vitro this factor inhibited IL-1 induced proliferative responses as well as PGE2 secretion by IL-1 induced fibroblasts. We also showed for the first time (Lymphokine Research 1988; 7(3): 268) that an IL-1 inhibitor can reduce IL-1 induced inflammatory effects. This study describes the specific effect of the M20 IL-1 Inhibitor on IL-1 induced parameters of inflammation: fever, leukocytosis and local foot pad swelling or lymph node enlargement. Purified preparations of the IL-1 Inhibitor, when injected together with IL-1, or before the IL-1, reduced fever, leukocytosis, foot pad swelling and lymph node enlargement caused by IL-1. Similar responses were obtained by injection of IL-6 or TNF, but were unaffected by the IL-1 Inhibitor, when injected together. These results indicate that the M20 IL-1 Inhibitor acts specifically on IL-1 induced responses in vivo. The potential importance of this factor as an anti-inflammatory and immune regulatory factor, is supported by the findings of this study.

Role of interleukin-1 inhibitory molecules in therapy of acute and chronic myelogenous leukemia

The poor outcome of conventional therapy of acute and chronic myelogenous leukemias (AML and CML) has prompted several groups to investigate new therapeutic directions. Data from various laboratories, including our own, indicate that both normal and leukemia precursors proliferate in response to growth factors. Furthermore, it has been shown that AML blasts, low-density cells from CML patients with advanced disease, and cultured bone marrow-adherent layers from CML blast crisis patients produce interleukin 1 (IL-1); this molecule may play a pivotal role in driving leukemia cell proliferation through autocrine or paracrine pathways. We have therefore hypothesized that interruption of the IL-1-mediated growth-stimulatory mechanism may suppress leukemia precursor multiplication. In searching for IL-1-inhibitory molecules that may be used clinically, we have investigated the in vitro effects of various IL-1 inhibitors including IL-1 receptor antagonist, soluble IL-1 receptors, and interleukin 4. Our studies suggest that IL-1 inhibitors can suppress clonogenic growth of cultured AML and CML progenitors and may hence be exploitable in clinical trials.

Interleukin-1 receptor antagonist

IL-1ra is the first described naturally occurring receptor antagonist of any cytokine or hormone-like molecule. IL-1ra is a member of the IL-1 family by three criteria: amino acid sequence homology of 26 to 30% to IL-1 beta and 19% to IL-1 alpha; similarities in gene structure; and common gene localization to human chromosome 2q14. Two structural variants of IL-1ra exist: sIL-1ra, a secretory molecule produced by monocytes, macrophages, neutrophils, fibroblasts, and other cells; and icIL-1ra, an intracellular molecule produced by keratinocytes and other epithelial cells, macrophages, and fibroblasts. IL-1ra production by monocytes, macrophages, and neutrophils may be regulated in a differential fashion with IL-1 beta. Human IL-1ra binds to both human IL-1RIs and IL-1RIIs on cell surfaces, although with 100-fold greater avidity to IL-1RIs. IL-1ra may bind preferentially to soluble IL-1RIs and not at all to soluble IL-1RIIs. IL-1ra competitively inhibits binding of both IL-1 alpha and IL-1 beta to cell surface receptors without inducing any discernible intracellular responses. All three forms of IL-1 may bind to IL-1 receptors in a similar fashion but IL-1ra may lack the secondary interactions necessary to trigger cell responses. A 100-fold or greater excess of IL-1ra over IL-1 may be necessary to inhibit biological responses to IL-1 both in vitro and in vivo. The roles of sIL-1ra and icIL-1ra in normal physiology or in host defense mechanisms remain unclear. The administration of IL-1ra blocks the effects of IL-1 in some animal models of septic shock, inflammatory arthritis, graft-versus-host disease, and inflammatory bowel disease. The preliminary results of clinical trials in humans indicate possible efficacy of IL-1ra in sepsis syndrome, rheumatoid arthritis, and GVHD.

The M20 IL-1 inhibitor prevents onset of adjuvant arthritis

Cytokines, specifically IL-1 and TNF, have been implicated as important mediators of joint destruction in rheumatoid arthritis (RA). Elevated levels of IL-1 in the joint fluid of patients with RA have been reported, as well as the presence of IL-1 inhibitory activity. We have reported the characterization of an inhibitor derived from a myelomonocytic cell line cloned in our laboratory which is specific for IL-1. This IL-1 inhibitor is protein in nature which specifically inhibits activity in vitro and in vivo. Previous studies showed that the inhibitor reduced acute inflammatory reactions associated with IL-1 (fever, leukocytosis, local foot pad swelling, lymph node enlargement and acute phase reactants). Thus it was of interest to study whether the M20 IL-1 inhibitor could modify adjuvant-induced chronic inflammation in rats, which is often used as a model for human RA. Administration of complete Freund's adjuvant (CFA) into Lewis rats, resulted in a severe adjuvant arthritis (AA) which reached peak severity after 14 days. Daily administration of IL-1 inhibitor, beginning after injection of CFA, abolished the appearance of AA. The parameters investigated were: joint swelling (the increase in diameter of joints), peri-articular erythema, limping of the rats and histological examination. The effect of the M20 IL-1 inhibitor was shown to be dose dependent and the IL-1 inhibitor alone had no adverse effects. These results indicate that the M20 IL-1 inhibitor may have a role in the treatment of AA and may be used to reduce pathological processes in joint inflammation.

The M20 IL-1 inhibitor. II. Biological characterization

Interleukin-1 (IL-1) is an important mediator in inflammation and immunological processes. The findings of native IL-1 inhibitors suggest a negative feedback mechanism to down-regulate IL-1 mediated acute inflammation. IL-1 inhibitors were also found elevated in disease states associated with high IL-1 levels. We have previously described one such IL-1 inhibitor derived from the human M20 myelomonocytic cell line. In this paper we present several biological and biochemical characteristics of the M20 IL-1 inhibitor. Various in vitro activities of the inhibitor are described and its IL-1 specificity in these assays is demonstrated. Purification of the inhibitor was performed by DEAE-high performance liquid chromatography, isoelectric focusing, gel filtration and dye ligand chromatography column. This protein factor has a MW of 52 +/- 4 kDa and a pI of 4.15 +/- 0.1. The inhibitor has no cross-reactivity against a panel of known cytokines (IL-1 alpha, IL-1 beta, IL-2, sIL-2R, IL-6, tumor necrosis factor (TNF), interferon-gamma (IFN-gamma)) and is distinct from the IL-1 receptor antagonist (IL-1ra). The purified IL-1 inhibitor was destroyed by trypsin, 2-mercaptoethanol, sodium dodecyl sulfate and extremes in pH and in temperature. Only IL-1 induced (but not the IL-2, IL-6 or TNF induced) thymocyte proliferation and PGE2 production by fibroblasts were inhibited by the inhibitor, thus showing specificity to IL-1 in these assays.

The M20 IL-1 inhibitor. I. Purification by preparative isoelectric focusing in free solution

An interleukin-1 (IL-1) inhibitor produced by the M20 myelomonocytic cell line has been shown to be active in various in vitro and in vivo IL-1 induced parameters. This inhibitor has been purified from the conditioned medium by gel filtration through a Sephacryl S-300 column or dye ligand chromatography on Affi-Gel blue column, followed by isoelectric focusing in free solution in the pH range 3-5 using the Rotofor cell. When gel filtration by FPLC with the Superose 12 column was used as the final step, the combined sequence of purification procedures resulted in a 1600-fold purification of the IL-1 inhibitor. The purified IL-1 inhibitor has a molecular weight of approximately 52 +/- 4 kDa and a pI of 4.15 +/- 0.1. By SDS-PAGE analysis the inhibitor preparation thus obtained showed the presence of two protein bands, while a few closely spaced protein bands were seen by analytical isoelectric focusing in polyacrylamide gels (pH 3-6). Some of these bands in PAGIF might correspond to different degrees of glycosylation of the inhibitory protein. Although the M20 IL-1 inhibitor has not yet been purified to homogeneity, it should be stressed that the procedures used, allowed us to remove the great majority of the proteins present in the medium in which the M20 cells were cultured, and to recover in satisfactory yield the inhibitor which we consider likely to be present in the conditioned medium in subnanomolar concentrations.

Interleukin-1: local production and modulation of human granulosa luteal cells steroidogenesis

OBJECTIVES

To investigate the possibility of local interleukin-1 (IL-1) and IL-1 inhibitor production by human granulosa and cumulus cells and to assess their direct effects on the steroidogenesis of these cells in vitro.

DESIGN

Prospective study.

PARTICIPANTS

Normal ovulatory women undergoing ovulation induction for in vitro fertilization.

INTERVENTION

Pretreatment of patients with gonadotropin-releasing hormone analogue, human menopausal gonadotropin, and human chorionic gonadotropin (hCG).

MAIN OUTCOME MEASURES

Retrieval and isolation of granulosa luteal cells and follicular fluid (FF). Granulosa luteal cells and cumulus cells cultured and analyzed by fluorescent activated cell sorter. Follicular fluid separated and bioassayed for IL-1 and IL-1 inhibitory activity. Steroid measurement performed. Interleukin-1 inhibitor purified. Interleukin-1 and IL-1 inhibitor bioassay performed. Statistical analysis made and interpreted.

RESULTS

Interleukin-1, but not IL-1 specific inhibitory activity, was found in granulosa and cumulus cell cultures and also in FF, only after its purification on a high-pressure liquid chromatography column. Under nonstimulated conditions, neither IL-1 nor IL-1 inhibitor had any effect on basal progesterone (P) or estradiol (E2) secretion. However, IL-1 inhibitor demonstrated significant (P < 0.01) inhibition of hCG-stimulated P secretion (from 200 to 110 ng/10,000 cells per 24 hours). In addition, IL-1 demonstrated a significant (P < 0.05) and dose-dependent inhibition of hCG-stimulated E2 production (from 6,832 +/- 460 to 4,237 +/- 141 pg/10,000 cells per 24 hours).

CONCLUSIONS

Interleukin-1 may exert a significant local autocrine regulatory role in the human ovary.

Interleukin-1 activity in lesioned peripheral nerve

The cytokine interleukin-1 (IL-1) is involved in a wide range of inflammatory and immune responses. As such, IL-1 could play a role in peripheral nerve repair mechanisms. Specifically, by its already established properties as a regulator of nerve growth factor (NGF) synthesis, and as a chemotactant to macrophages. We examined, therefore, IL-1 production in injured mouse peripheral nerve. Injured nerve segments were incubated in serum free medium to produce conditioned medium (CM) that was then tested for IL-1 activity in a thymocyte proliferation assay. CM induced thymocyte proliferation in a dose-dependent manner. Proliferation was inhibited by the M20 IL-1 inhibitor, the IL-1 receptor antagonist, and antisera raised against recombinant mouse IL-1 alpha. Inhibitions produced by these three specific inhibitors of IL-1-induced thymocyte proliferation strongly suggest that proliferation induced by CM was mediated largely by IL-1 secreted by non-neuronal cells residing in the damaged nerve. IL-1 activity was detected within hours after lesion, and 1 week thereafter. The rapid and prolonged production of IL-1 indicates that IL-1-dependent mechanisms can play roles in the response of the peripheral nerve to injury: degeneration and regeneration. The regulation of NGF synthesis, and the recruitment of white blood cells, macrophages in particular, from blood into the damaged nerve tissue, are two such mechanisms.

Native cytokine antagonists

Cytokines orchestrate the complex homeostasis of cells and tissues by acting in both an autocrine and paracrine fashion. The processes responsible for regulation of cytokines is not well understood. This chapter has summarized what is known about antagonism and inhibition of the action of cytokines. Several concepts have emerged from work in this area. At least two cytokines (IL-1 alpha and IL-1 beta) have an endogenous receptor antagonist, the IL-1 receptor antagonist. This is the first example of one endogenous molecule directly blocking the binding of another molecule to its receptor: most forms of regulation occur through independent receptors. Several cytokines, including TNF, IFN-gamma, IL-2 and IL-4, are inhibited by soluble receptors. Several cytokines, including IL-10, TGF-beta and MDF, act to inhibit other cytokines. It is likely that these inhibitors will be found to have pleiotropic actions in vivo. Finally, we describe antibody inhibition of cytokines. Detailed studies will be required to understand the complex interplay of the aforementioned cytokine inhibitors and the processes they regulate.

Chemo-immunotherapy in patients with metastatic melanoma using sequential treatment with dacarbazine and recombinant human interleukin-2: evaluation of hematologic and immunologic parameters and correlation with clinical response

We have treated 18 patients with metastatic malignant melanoma (MM) with high-dose IL-2 administered by continuous iv infusion in combination with dacarbazine (DTIC), and correlated the clinical response with various hematologic and immunologic parameters. Two regimens differing in the sequence of treatment were employed, and 1-6 treatment cycles were given, depending on patient response. Two patients had a complete response (CR, 46+m, 14m), two patients a partial response (PR, 16m,6m), one a minimal response and four had a stable disease lasting 2-7 months, thus the response rate (CR+PR) was 22%. None of the following parameters, tested prior to initiation of the therapy and 1-2 days after termination of each course of IL-2, correlated with the clinical response: WBC counts (total and differential), levels of blood CD4 and CD8 T cells, NK cells, monocytes and B cells, production of IL-1 and IL-1 inhibitor by monocytes, responsiveness to 3 mitogens, NK/LAK cell activity, and serum levels of IL-1 alpha, IL-2, soluble IL-2 receptor, and TNF alpha. The only prognostic parameter was the greater increase in the level of IL-2 receptor (Tac)-bearing lymphocytes in the responding patients after 1-3 cycles of IL-2. The data suggests that non-specific immune parameters have no prognostic value for patients undergoing IL-2-based immunotherapy.

Inflammatory cytokines: interleukin-1 and tumor necrosis factor as effector molecules in autoimmune diseases

The nature of the events that precipitate autoimmune diseases varies. Interleukin-1 and tumor necrosis factor do not precipitate autoimmune diseases but rather act as effector molecules. They induce eicosanoid and nitric oxide synthesis, stimulate collagenases and collagen synthesis, and trigger the genes for other cytokines, namely interleukin-2, interleukin-6 and interleukin-8. The ability to block interleukin-1 with the receptor antagonist, and tumor necrosis factor with soluble receptors, has given investigators specific tools to test the role of these two cytokines in the pathological processes of autoimmune disease.

Blocking IL-1: interleukin 1 receptor antagonist in vivo and in vitro

Clinical and experimental evidence suggests that shock, arthritis, osteoporosis, colitis, leukemia, diabetes, wasting and atherosclerosis are mediated, in part, by interleukin 1 (IL-1). Inhibition of this cytokine has been a strategy for studying disease and for new drug development. A naturally-occurring IL-1 inhibitor (IL-1 receptor antagonist, IL-1ra) that blocks binding of IL-1 to its receptors has been cloned and produced in recombinant organisms. IL-1ra reduces the severity of sepsis, colitis, arthritis and diabetes in animals and is presently being tested in humans with arthritis, shock and myelogenous leukemia.

Recombinant human interleukin-1 suppresses lipoprotein lipase activity, but not expression of lipoprotein lipase mRNA in mesenchymal rat heart cell cultures

The effect of human recombinant interleukin-1 (IL-1) on the regulation of lipoprotein lipase (LPL) was studied in rat heart mesenchymal cell cultures. A time-dependent reduction in enzyme activity occurred with a 30% fall after 1 h. The suppression of enzyme activity was accompanied by a commensurate reduction in enzyme mass. The reduction in LPL activity was most prominent in the heparin releasable pool; IL-1 treatment resulted in a 7.2-8.3-fold decrease in the functional compartment and a 2.5-2.8-fold decrease in residual cellular activity. The effect of IL-1 could be prevented by the addition of the IL-1 inhibitor. However, in contradistinction to the effect of tumor necrosis factor (TNF), there was no change in LPL mRNA in cultures treated with IL-1. The present results show that the regulation of LPL in mesenchymal heart cell cultures by IL-1 occurs posttranscriptionally, as has been shown in 3T3 cells. The more pronounced effect on LPL activity in the functional pool suggests that IL-1 treatment might have influenced also the processing and/or transport of the enzyme to the cell surface.

Purification and characterization of a 26-kDa competitive inhibitor of interleukin 1

The urine of patients with fever above 39 degrees C contains an inhibitor of interleukin 1. Herein we describe the purification of the interleukin 1 inhibitor by ion-exchange chromatography, hydrophobic chromatography, gel filtration and negative immunosorption. The purified protein has a molecular weight of 26,000; its size is reduced to 24,000 upon treatment with endoglycosidase F. The IL 1 inhibitor is a competitive inhibitor and acts by binding to the IL 1 receptor. The inhibitor recognizes the murine and human IL 1 receptor with similar affinity. The purified IL 1 inhibitor has a specific activity of 3 x 10(7) to 4.5 x 10(7) units/mg as tested on the human astrocytoma (U-373) cell proliferation bioassay and murine EL4.6.1 cell IL 1 receptor-binding assay.

Inhibition of interleukin 1 (IL-1)-elicited leukocytosis and LPS-induced fever by soluble immune response suppressor (SIRS)

IL-1-induced leukocytosis was inhibited or blocked in a dose-dependent manner by SIRS, an antigen-nonspecific suppressive lymphokine, when administered intravenously or per os to CBA mice. Timing experiments showed that SIRS effectively inhibited the leukocytosis when administered within 30 minutes of the IL-1. An antipyrogenic activity of SIRS was observed in rabbits injected intravenously with LPS. SIRS, given intravenously in one or two doses, markedly reduced LPS-induced fever. SIRS (2000 units) was a more effective antipyretic agent than aspirin (3 mg/kg body weight, intramuscularly). The results suggest that SIRS may be a potential drug for use in IL-1-mediated disorders.

Production of interleukin-1 (IL-1) and a specific IL-1 inhibitor during human monocyte-macrophage differentiation: influence of GM-CSF

Mononuclear phagocytes release several factors involved in host defense and inflammation. Of these, interleukin-1 (IL-1) has multiple biological activities which are controlled at different levels including modulation of gene expression, protein synthesis or secretion, and interaction with inhibitors. We have investigated the production of IL-1 alpha and beta as well as the production of a specific IL-1 inhibitor (IL-1 INH) during the in vitro maturation of human monocyte-macrophages. Highly purified monocytes isolated by counterflow centrifugal elutriation were cultured up to six weeks, producing high levels of IL-1 alpha and beta during the first week of culture. Shortly after the first week bioactivity of IL-1 decreased, preceding a decrease of IL-1 immunoreactivity. In contrast, IL-1 inhibitory activity reached a peak during the third week and remained detectable up to six weeks. Granulocyte-monocyte-colony-stimulating factor GM-CSF increased the production of IL-1 INH by approximately 20%, but did not affect IL-1 production. The IL-1 INH, apparent molecular weight approximately 23 kD, blocks the binding of [125I]IL-1 alpha to its receptor. The balance between the production of IL-1 and its antagonist may be important for the regulation of the immune response and chronic inflammation during pathological processes.

Native interleukin 1 inhibitors

Much information has accumulated on the isolation and characterization of a heterogeneous group of molecules that inhibit one or more of the bioactivities of interleukin 1. In this review James Larrick discusses the biological and biochemical data available on several of these native interleukin 1 inhibitors, some of which have additional, unexpected activities.

Production of interleukin 1 inhibitors by the murine macrophage cell line P388D1 which produces interleukin 1

A murine macrophage cell line P388D1 in in vitro culture without any specific stimulation produced both interleukin 1 (IL1) and IL1 inhibitor which inhibits mitogenic response of murine thymocytes to IL1 in the culture fluids. The factor(s) responsible for inhibiting IL1-induced thymocyte proliferation consisted of at least two molecules: factor I (FI) with an isoelectric point of 6.0 and factor II (FII) with an isoelectric point of 5.3, both of which had a similar m.w. of 40-60 kDa. FI activity was sensitive to heat (56 C) treatment and acid pH (3.0) treatment, while FII was resistant to both treatments. Both FI and FII inhibited mitogenic responses of thymocytes to IL1, but not proliferation of murine lymphoid cells induced by other interleukins, namely, IL2, IL3, or IL4. Neither showed any inhibition of spontaneous proliferation of murine tumor cell lines, suggesting that inhibition was specific for IL1, but not nonspecifically inhibiting for cellular DNA. These IL1 inhibitors were also suggested to be acting in the early phase of interaction between IL1 and lymphoid cells. The possible role of these inhibitors as representatives of regulatory substances, which normally control IL1 activities either in the levels of inflammation or immune responses, was discussed.

A human urine-derived interleukin 1 inhibitor. Homology with deoxyribonuclease I

We have previously reported that the urine of febrile humans contained large quantities of an inhibitor of IL-1-induced murine thymocyte proliferation that was a glycoprotein between 30 and 40 kD in size. In the present study this factor has been purified to homogeneity using a sequence of eight purification steps (ammonium sulfate precipitation, ion exchange chromatography, molecular sieve chromatography, hydrophobic affinity chromatography, hydroxylapatite chromatography, fast protein liquid chromatography, and two HPLC steps). SDS-PAGE analysis indicates that the purified material is a 38-kD molecule. Evidence based on a partial amino acid sequence analysis as well as enzyme studies indicates that this inhibitor is a type of human DNase I.

Cytostatic product(s) released by activated macrophages, unrelated to interleukin 1, tumor necrosis factor alpha, and interferon-alpha/beta

Murine peritoneal macrophages activated for cytotoxicity by trehalose dimycolate in vivo and lipopolysaccharide in vitro released cytostatic factor(s) against EMT6 target cells, in 8-hr conditioned medium (CM). The cytostatic factor(s) completely blocked DNA synthesis by EMT6 cells within 16 hr. Other cell lines are less sensitive (P815 and R-L929) or resistant (KB and HT29) to the cytostatic effect of CM. The anti-proliferative activity of CM had a MW greater than 10,000 Da, as judged by ultrafiltration. It was destroyed by proteases and strongly inhibited by P815 cell product(s). Conditioned media from nonactivated macrophages were not cytostatic against EMT6 cells. No relationship was found between cytostatic factor(s) in CM and interleukin 1 (IL-1), tumor necrosis factor alpha (TNF-alpha), and interferon-alpha/beta (IFN-alpha/beta): the growth of EMT6 cells was unaffected by Hu.r.IL-is and Hu.r.TNF-alpha and was only slightly inhibited by IFN-alpha/beta. Furthermore, cytostatic CM contained low levels of TNF and IFN activities. Finally, antibodies raised against murine IFN-alpha/beta had no effect on the cytostatic activity of CM.

The role of tumor necrosis factor and interleukin 1 in the immunoinflammatory response

Monocytes and tissue macrophages produce at least two groups of protein mediators of inflammation, interleukin 1 (IL-1) and tumor necrosis factor (TNF). Recent studies have emphasized that TNF and IL-1 modulate the inflammatory function of endothelial cells, leukocytes, and fibroblasts. Although these cytokines share a number of biologic properties, they have quite distinct gene and protein structures. It is our purpose to focus on the role of these mediators in inflammation.