Recombinant expression, biochemical characterization, and biological activities of the human MGSA/gro protein

Melanoma growth stimulatory activity (MGSA) is a mitogenic protein secreted by Hs294T melanoma cells that corresponds to the polypeptide encoded by the human gro gene. The MGSA/gro cDNA has been expressed in mammalian cells and the secreted recombinant factor has been purified. Biochemical and biological characterization shows that the recombinant protein is identical with the natural protein and is devoid of posttranslational glycosylation, sulfation, and phosphorylation. The two C-terminal amino acids are proteolytically removed from the mature recombinant MGSA, indicating a length of 71 instead of the predicted 73 amino acids. The recombinant MGSA is mitogenically active on the Hs294T melanoma cells. The purified MGSA competes with interleukin 8 for binding to neutrophil receptors and exhibits neutrophil chemotactic activity equivalent to that of interleukin 8.

Detection of interleukin 8 biological activity in synovial fluids from patients with rheumatoid arthritis and production of interleukin 8 mRNA by isolated synovial cells

The presence of neutrophils in the synovial joint of patients with rheumatoid arthritis (RA) is thought to be due to the activity of chemotactic factors released by activated cells in the joint. We have shown in this report, for the first time, the abundance of one such factor, interleukin 8 (IL 8), in the synovial fluid of patients both with RA and other non-RA joint diseases, and the spontaneous production of IL 8 mRNA by RA synovial cells in culture. There was no correlation between the levels of chemotactic activity and IL 8 protein, suggesting that other factors with similar neutrophil chemotactic activity are also present in the synovial fluid exudate. In support of this concept neither the level of chemotactic activity nor IL 8 protein levels correlated with neutrophil or leukocyte infiltration, indicating that the mechanism of migration into the inflammatory environment of the joint is complex. Such migration is likely to be due to a number of chemotactic signals in addition to IL 8, which may either synergize with, or inhibit, the action of IL 8.

[A case of facial diplegia due to EB virus infection]

A case of facial diplegia due to EB virus infection is reported. A 56-year-old man developed headache, arthralgia and low grade fever. Two days later he noted dysesthesia of the bilateral extremities. Eight days later, disturbances of bilateral mouth and eye closing appeared, which brought him to our hospital on January 6, 1986. Neurological examinations disclosed bilateral peripheral facial palsy and glove and stocking type sensory impairment. Muscle weakness, pathological reflexes were not noted. Examination of CSF on admission revealed a cell count of 63/mm3 and a protein concentration of 45 mg/dl. The lumbar puncture, done 7 days later, revealed a cell count of 17/mm3, and a protein concentration of 41 mg/dl. Serum Epstein-Barr virus titers were times 40 (VCA IgG) and less than X10 (EBNA) on admission. Nine days later, serum EB virus titer increased to times 160 (VCA IgG). He was diagnosed as having polyneuropathy due to EB virus infection from the clinical manifestations and serum antibody titer for EB virus. EB virus infection produces various neurological manifestations. Facial nerve palsy is reported as one of the rare complications. However, most of these cases are associated with Guillain-Barré syndrome (GBS). As far as we know, only 10 cases of bilateral facial nerve palsy in the absence of GBS have appeared in the literature. In our case, bilateral facial nerve palsy appeared as a part of polyneuropathy in the absence of GBS. EB virus should be considered as one of etiologies of bilateral facial nerve palsy.

Identification of calcium-activated neutral protease as a processing enzyme of human interleukin 1 alpha

We describe here the involvement of calcium-activated neutral protease (CANP or calpain, EC 3.4.22.17) in calcium-dependent proteolytic processing of the precursor of human interleukin 1 alpha (IL-1 alpha) into mature IL-1 alpha. Calcium ionophore ionomycin enhanced proteolytic processing of pre-IL-1 alpha and the release of mature IL-1 alpha either from lipopolysaccharide (LPS)-activated human adherent mononuclear cells or from a human bladder carcinoma cell line (HTB9 5637) that constitutively produces human IL-1 alpha and -beta. The proteolytic processing of pre-IL-1 alpha was completely inhibited by EGTA. Similar calcium-dependent proteolytic processing of pre-IL-1 alpha was also observed with lysates of either LPS-activated human adherent mononuclear cells or HTB9 5637 cells. Since the optimal pH for processing was between 7 and 8, and E-64 (a cysteine protease inhibitor) and leupeptin (a serine and cysteine protease inhibitor) both inhibited this processing by cell lysates, we hypothesized that a calcium-activated neutral protease, CANP, might be responsible for this processing. This hypothesis was supported by data showing that the specific CANP inhibitor peptide inhibited this proteolysis in cell lysates in a dose-dependent fashion (IC50 = 0.05 microM) and that treatment of pre-IL-1 alpha with purified CANP yielded the 17-kDa mature form of IL-1 alpha, which has an amino terminus identical with that reported for mature human IL-1 alpha. Taken together, these findings indicate that calcium-dependent proteolytic processing of pre-IL-1 alpha is selectively mediated by CANP.

Fluorometric examination of tissue amyloid fibrils in murine senile amyloidosis: use of the fluorescent indicator, thioflavine T

Thioflavine T, a fluorescent indicator of amyloid fibrils (Naiki H, Higuchi K, Hosokawa M, Takeda T: Anal Biochem 177:244, 1989), has been tested in unfractionated tissue homogenates. With 250 nM thioflavine T, liver homogenates from a 17-month-old SAM-P/1 (senescence accelerated mouse-prone), which contained amyloid fibrils in murine senile amyloidosis (fASSAM) fluoresced brightly, whereas normal liver homogenates showed a negligible fluorescence. The following evidence confirmed that the fluorescence in the unfractionated preparations specifically represented fASSAM. The fluorescence of fASSAM deposited liver tissue was diminished to the level of the normal liver when the structure of the amyloid fibrils was disrupted by guanidine-HCl. Second, about 90% of the fluorescence of fASSAM deposited liver tissue was fractionated in the water-soluble fraction, in which amyloid fibrils are generally enriched. We then determined the concentration of fASSAM in the tissue, from the fluorescence and using the standard curve described in the above mentioned report. Lower limits of fASSAM determination were about 1 microgram/mg of tissue. A marked regional heterogeneity of fASSAM deposition was observed in the liver. We observed a linear correlation between fASSAM concentration and percentage of amyloid positive area in the liver. Age-dependent increases in fASSAM concentrations and total fASSAM contents were noted in the liver and spleen of 11 to 15-month-old SAM-P/1. There was also a positive correlation between the organ weight and fASSAM concentrations in both organs. Thus, thioflavine T is of practical use for the determination of fASSAM concentrations in the tissue.

Properties of monocyte chemotactic and activating factor (MCAF) purified from a human fibrosarcoma cell line

A monocyte chemotactic and activating factor (MCAF) has been purified from TNF-stimulated 8387 human fibrosarcoma cell line-conditioned media. The purified MCAF showed microheterogeneity yielding two bands on SDS-PAGE analysis. Fibrosarcoma-derived MCAF specifically competed with THP-1 (a human monocytic cell line)-derived 125I-labeled MCAF in binding to human PBMC, whereas a similar basic heparin-binding leukocyte chemoattractant, IL-8, did not. The purified MCAF stimulated superoxide anion and N-acetyl beta-D glucosaminidase-releasing activity in human monocytes, as well as monocyte cytostatic augmenting activity against tumor cells and chemotactic activity for monocytes. When injected subcutaneously into Lewis rat ears, the purified human MCAF also induced considerable in vivo local monocyte infiltration beginning at 3 h and becoming maximal at 18 h. In conclusion, the data presented in this paper indicate that MCAF is a potent activator of monocytes as well as a monocyte recruitment factor that acts through receptors that are specific for this novel molecule. This novel cytokine might have an important role in tumor growth control due to its ability to attract and activate monocytes.

Induction of haptotactic migration of melanoma cells by neutrophil activating protein/interleukin-8

Natural or recombinant neutrophil activating cytokine (IL-8) induced migration across polycarbonate filters of human A 2058 melanoma cells. Anti-IL-8 antibodies blocked IL-8 induced melanoma cell migration. Checkerboard experiments revealed a gradient-dependent response of A2058 melanoma cells to IL-8. Filters exposed to IL-8 and washed supported melanoma cell migration, thus implying a haptotactic component in the response. The homologous polypeptide platelet factor 4 was inactive. The observation that IL-8 affects melanoma cells emphasizes the need for a comprehensive analysis of the spectrum of action of platelet factor 4-related peptides. The effect of the inflammatory cytokine IL-8 on melanoma cells may be relevant to augmented secondary localization of tumors at sites of inflammation.

Calcium-dependent binding of phosphorylated human pre interleukin 1 alpha to phospholipids

The effect of phosphorylation of pre interleukin 1 alpha (IL 1 alpha) on its association with various phospholipids was investigated. We prepared genetically engineered truncated human pre IL 1 alpha (residues 64 to 271) and phosphorylated this pre IL 1 alpha in vitro by using the catalytic subunit of cAMP-dependent protein kinase. Phosphorylated truncated pre IL 1 alpha selectively binds to acidic phospholipids including phosphatidic acid, phosphatidylserine, and phosphatidylinositol, but not to other phospholipids (phosphatidylcholine and phosphatidylethanolamine). This binding required divalent cations: Ca2+ or Mn2+, but not Mg2+. In order to obtain half-maximal binding of pre IL 1 alpha to phosphatidic acid or phosphatidylserine, Ca2+ between 5 and 100 microM was required. Unphosphorylated pre IL 1 alpha did not bind to phosphatidylserine, indicating that phosphorylation is required for this binding. Phosphorylated pre IL 1 alpha did not bind to intact peripheral blood mononuclear cells irrespective of lipopolysaccharide stimulation, but did bind to membrane vesicles prepared from these cells in the presence of calcium. Furthermore, phosphorylated pre IL 1 alpha bound only to inside-out ghosts, but not right-side-out ghosts, prepared from human red blood cells. Taken together, these data suggest that phosphorylated pre IL 1 alpha binds to the inner surface of plasma membrane in a Ca2(+)- and phospholipid-dependent manner.

Crystallization of human interleukin-8. A protein chemotactic for neutrophils and T-lymphocytes

Interleukin-8 is a 72-residue peptide which is chemotactic for neutrophils and T-lymphocytes. It crystallizes in space group P3(1)21 or P3(2)21 with unit cell dimensions of a = b = 40.3 and c = 90.1 A. X-ray diffraction data have been measured to 1.6-A resolution.

Monocyte chemotactic and activating factor gene expression induced in endothelial cells by IL-1 and tumor necrosis factor

Inflammation, thrombosis, and immunity involve close interactions between leukocytes and vascular endothelium. Endothelial cells represent both targets and producers of lymphokines. Our study was designed to define the capacity of human endothelial cells (HEC) to produce a novel, recently purified, and molecularly cloned monocyte chemotactic and activating factor. This factor has been identified in the culture supernatants of tumor cell lines (tumor-derived chemotactic factor (TDCF)) as well as activated monocytes and fibroblasts (monocyte chemotactic and activating protein, MCAF, or monocyte chemoattractant protein-1, MCP-1). IL-1 induced high levels of production of chemotactic activity for monocytes in culture supernatants of HEC. IL-1-treated HEC expressed high levels of MCAF/MCP-1/TDCF mRNA transcripts, as assessed by Northern blot analysis. TNF and LPS, unlike IL-6, also induced MCAF/MCP-1/TDCF gene expression. Nuclear run off experiments revealed that IL-1-activated transcription of the MCAF/MCP-1/TDCF gene. The production of MCAF/MCP-1/TDCF may represent one of the mechanisms whereby endothelial cells, exposed to inflammatory signals, participate in the regulation of leukocyte extravasation. Production of this cytokine by vascular cells may in particular be relevant under conditions of selective extravasation and activation of mononuclear phagocytes.

Monocyte chemotactic and activating factor gene expression induced in endothelial cells by IL-1 and tumor necrosis factor

Inflammation, thrombosis, and immunity involve close interactions between leukocytes and vascular endothelium. Endothelial cells represent both targets and producers of lymphokines. Our study was designed to define the capacity of human endothelial cells (HEC) to produce a novel, recently purified, and molecularly cloned monocyte chemotactic and activating factor. This factor has been identified in the culture supernatants of tumor cell lines (tumor-derived chemotactic factor (TDCF)) as well as activated monocytes and fibroblasts (monocyte chemotactic and activating protein, MCAF, or monocyte chemoattractant protein-1, MCP-1). IL-1 induced high levels of production of chemotactic activity for monocytes in culture supernatants of HEC. IL-1-treated HEC expressed high levels of MCAF/MCP-1/TDCF mRNA transcripts, as assessed by Northern blot analysis. TNF and LPS, unlike IL-6, also induced MCAF/MCP-1/TDCF gene expression. Nuclear run off experiments revealed that IL-1-activated transcription of the MCAF/MCP-1/TDCF gene. The production of MCAF/MCP-1/TDCF may represent one of the mechanisms whereby endothelial cells, exposed to inflammatory signals, participate in the regulation of leukocyte extravasation. Production of this cytokine by vascular cells may in particular be relevant under conditions of selective extravasation and activation of mononuclear phagocytes.

IL-1 transcriptionally activates the neutrophil chemotactic factor/IL-8 gene in endothelial cells

Leucocytes and vascular cells interact closely in inflammation and immunity and cytokines are important mediators of this interaction. The present study was designed to define the capacity of human endothelial cells (HEC) to produce a monocyte-derived neutrophil chemotactic factor (provisionally termed IL-8). IL-8 is a polypeptide chemotactic for neutrophils originally identified in the culture supernatant of lipopolysaccharide (LPS)-stimulated monocytes. IL-1 induced high levels of production of neutrophil chemotactic activity in culture supernatants of HEC. Optimal stimulation of activity was observed when HEC were cultured with 10-100 ng/ml IL-1 beta for 16 hr. Anti-IL-8 antibody blocked the chemotactic activity for neutrophils of IL-1-activated HEC supernatants. IL-1-treated HEC expressed high levels of IL-8 mRNA transcripts, as assessed by Northern blot analysis. Tumour necrosis factor (TNF) and LPS, unlike the inflammatory monokine IL-6, also induced IL-8 expression. Nuclear run-off experiments revealed that IL-1 activated transcription of the IL-8 gene. The production of IL-8 may represent a mechanism whereby endothelial cells, exposed to inflammatory signals, participate in the regulation of neutrophil extravasation.

Functional activation of human neutrophils by recombinant monocyte-derived neutrophil chemotactic factor/IL-8

Monocyte-derived neutrophil chemotactic factor (MDNCF)/IL-8, a novel cytokine, distinct from IL-1 and TNF was recently purified and cloned. This study was performed to investigate the biologic effect of recombinant MDNCF/IL-8 on human polymorphonuclear neutrophils (PMN) by assessment of their growth inhibitory activity against Candida albicans. The chemoattractant, FMLP was used as a positive control. We demonstrated that MDNCF/IL-8, similar to FMLP, effectively enhanced PMN-mediated anti-Candida activity. MDNCF/IL-8, from 1.0 to 1000 ng/mol, enhanced PMN-mediated anti-Candida activity, whereas FMLP was effective from 10(-10) to 10(-7) M. The optimal dose of MDNCF/IL-8 for PMN stimulation was 10 ng/ml which equalled the optimal chemoattractant dose. MDNCF/IL-8 itself, like FMLP, had no direct effect on Candida growth at any concentration and it stimulated antifungal activity only in PMN but not in monocytes. Interestingly, MDNCF/IL-8 failed to stimulate directly the production of superoxide from PMN or prime the respiratory burst of PMN exposed to FMLP. However, MDNCF/IL-8 was capable of releasing azurophilic enzymes from cytochalasin B-treated PMN into the extracellular space. Enhancement of PMN anti-Candida activity and release of azurophilic enzymes from PMN by MDNCF/IL-8 were inhibited in the presence of colchicine, which is a known inhibitor of degranulation. These results suggest that MDNCF/IL-8 induced antifungal action of PMN via oxygen-independent pathways. Furthermore, MDNCF/IL-8 induction of anti-Candida action by PMN was inhibited by pretreatment with Bordetella pertussis toxin, suggesting that enhancement of PMN antifungal activity by MDNCF/IL-8, as well as by FMLP, may be mediated by a GTP-binding protein.

Functional activation of human neutrophils by recombinant monocyte-derived neutrophil chemotactic factor/IL-8

Monocyte-derived neutrophil chemotactic factor (MDNCF)/IL-8, a novel cytokine, distinct from IL-1 and TNF was recently purified and cloned. This study was performed to investigate the biologic effect of recombinant MDNCF/IL-8 on human polymorphonuclear neutrophils (PMN) by assessment of their growth inhibitory activity against Candida albicans. The chemoattractant, FMLP was used as a positive control. We demonstrated that MDNCF/IL-8, similar to FMLP, effectively enhanced PMN-mediated anti-Candida activity. MDNCF/IL-8, from 1.0 to 1000 ng/mol, enhanced PMN-mediated anti-Candida activity, whereas FMLP was effective from 10(-10) to 10(-7) M. The optimal dose of MDNCF/IL-8 for PMN stimulation was 10 ng/ml which equalled the optimal chemoattractant dose. MDNCF/IL-8 itself, like FMLP, had no direct effect on Candida growth at any concentration and it stimulated antifungal activity only in PMN but not in monocytes. Interestingly, MDNCF/IL-8 failed to stimulate directly the production of superoxide from PMN or prime the respiratory burst of PMN exposed to FMLP. However, MDNCF/IL-8 was capable of releasing azurophilic enzymes from cytochalasin B-treated PMN into the extracellular space. Enhancement of PMN anti-Candida activity and release of azurophilic enzymes from PMN by MDNCF/IL-8 were inhibited in the presence of colchicine, which is a known inhibitor of degranulation. These results suggest that MDNCF/IL-8 induced antifungal action of PMN via oxygen-independent pathways. Furthermore, MDNCF/IL-8 induction of anti-Candida action by PMN was inhibited by pretreatment with Bordetella pertussis toxin, suggesting that enhancement of PMN antifungal activity by MDNCF/IL-8, as well as by FMLP, may be mediated by a GTP-binding protein.

Three-dimensional structure of interleukin 8 in solution

The solution structure of the interleukin 8 (IL-8) dimer has been solved by nuclear magnetic resonance (NMR) spectroscopy and hybrid distance geometry-dynamical simulated annealing calculations. The structure determination is based on a total of 1880 experimental distance restraints (of which 82 are intersubunit) and 362 torsion angle restraints (comprising phi, psi, and chi 1 torsion angles). A total of 30 simulated annealing structures were calculated, and the atomic rms distribution about the mean coordinate positions (excluding residues 1-5 of each subunit) is 0.41 +/- 0.08 A for the backbone atoms and 0.90 +/- 0.08 A for all atoms. The three-dimensional solution structure of the IL-8 dimer reveals a structural motif in which two symmetry-related antiparallel alpha-helices, approximately 24 A long and separated by about 14 A, lie on top of a six-stranded antiparallel beta-sheet platform derived from two three-stranded Greek keys, one from each monomer unit. The general architecture is similar to that of the alpha 1/alpha 2 domains of the human class I histocompatibility antigen HLA-A2. It is suggested that the two alpha-helices form the binding site for the cellular receptor and that the specificity of IL-8, as well as that of a number of related proteins involved in cell-specific chemotaxis, mediation of cell growth, and the inflammatory response, is achieved by the distinct distribution of charged and polar residues at the surface of the helices.

[Spinal subarachnoid hemorrhage due to spinal ependymoma presenting findings mimicking subacute meningitis]

A case of spinal ependymoma showing spinal subarachnoid hemorrhage with findings mimicking subacute meningitis is reported. A 33-year-old man was admitted to our hospital because of headache, low back pain and low grade fever on June 8, 1982. Ten years ago he had experienced an episode of abrupt onset lumbago and headache. Subarachnoid hemorrhage was suspected because of bloody cerebrospinal fluid, but cerebral angiography failed to demonstrate any abnormalities. On admission physical examination revealed nuchal rigidity, Kernig's sign and percussion tenderness on 5th lumbar spine. Lumbar puncture showed bloody cerebrospinal fluid. Cell counts were 217 per cubic millimeter (neutrophil: lymphocyte = 27.73), protein was 396 mg/dl and sugar level was 18 mg/dl. Myelography showed an intradural extramedullary tumor at the spinal level of L1-L2. Spinal MRI and CT scan also demonstrated a spinal tumor at the same level. Laminectomy and total resection of the spinal tumor were performed and a diagnosis of myxopapillary ependymoma was made histologically. He was discharged about a month later without any neurological deficits. The development of subarachnoid hemorrhage due to spinal tumor is rare. There are about 50 cases of spinal subarachnoid hemorrhage due to spinal tumor in the literature, including three cases in Japan. Two cases presenting CSF findings mimicking bacterial meningitis have been reported in the literature, but there is no report of subarachnoid hemorrhage due to spinal tumor that presents findings mimicking subacute meningitis similar to our case. From these results, it is suggested that subarachnoid hemorrhage due to spinal ependymoma may reveal various CSF findings. In cases suggesting bacterial or subacute meningitis with bloody CSF and acute onset, the possibility of spinal subarachnoid hemorrhage due to rupture of a spinal tumor, especially ependymoma, should be considered.

Interleukin 8 (monocyte-derived neutrophil chemotactic factor) dynamically regulates its own receptor expression on human neutrophils

The regulation of monocyte-derived neutrophil chemotactic factor (MDNCF)/interleukin 8 (IL 8) receptor expression by the MDNCF/IL 8 ligand was examined using freshly isolated human peripheral blood neutrophils. MDNCF/IL 8 down-regulated greater than 90% of its own receptor expression within 10 min at 37 degrees C. This down-regulation was associated with internalization of the ligand. The radiolabeled MDNCF/IL 8 molecules after internalization were proteolytically degraded, and trichloroacetic acid-soluble molecules were released into the culture medium starting at 60 min. Lysosomotropic agents could inhibit this degradation of ligand suggesting the involvement of lysosomal enzymes in this proteolytic digestion. MDNCF/IL 8 receptors reappeared on the cell surface within 10 min after removal of free ligands from the culture medium. Cycloheximide did not alter the reappearance of the receptor suggesting that de novo protein synthesis of MDNCF/Il 8 receptors is not involved in this event and that receptors probably recycled. The addition of lysosomotropic agents partially inhibited the reappearance/recycling of the receptors, although none of these agents inhibited the binding of ligand to the surface receptors or ligand internalization. Ammonium chloride reduced the MDNCF/IL 8-induced neutrophil chemotactic response in a dose-dependent fashion. These data suggest that MDNCF/IL 8 receptor expression is dynamically regulated by MDNCF/IL 8 and that the rapid recycling of MDNCF/IL 8 receptors may be essential for the chemotactic response of neutrophils.

Monocyte-derived neutrophil chemotactic factor (MDNCF/IL-8) resides in a gene cluster along with several other members of the platelet factor 4 gene superfamily

Monocyte-derived neutrophil chemotactic factor (MDNCF/IL-8, suggested gene symbol IL8) is a cytokine that chemoattracts and activates neutrophils. Using a panel of human-rodent cell hybrids that preferentially segregate human chromosomes and in situ hybridization, the MDNCF/IL-8 gene was placed on the human gene map at position 4q12-q21. This is the same location where at least three other members (platelet factor 4, melanoma growth stimulatory activity, and interferon-gamma induced factor) of the platelet factor 4 gene super-family reside. In addition, a restriction fragment length polymorphism was identified using MDNCF as a probe in screening genomic DNA digested with HindIII from unrelated individuals.

Enhanced phosphorylation of 65 and 74 kDa proteins by tumor necrosis factor and interleukin-1 in human peripheral blood mononuclear cells

Tumor necrosis factor (TNF) and interleukin-1 (IL-1) enhanced the phosphorylation of identical cytosolic 65 kDa protein (P65 or l-plastin) and 74 kDa protein (P74) at serine residues in human peripheral blood mononuclear cells (PBMC). The isoelectric points of P65 and P74 were 5.6 and 4.7 to 5.0, respectively. The phosphorylation of these proteins increased with a few minutes and reached maximal levels of approximately 3 times the unstimulated levels by 10 minutes. The phosphorylation of P65 and P74 was extensively enhanced by a potent protein kinase C (PKC) activator, PMA. However, there was no translocation of PKC from cytosol to membrane in PBMC that was stimulated with either TNF or IL-1, which suggests that PKC does not participate in TNF or IL-1 signal transduction. cAMP dependent protein (PKA) activators, forskolin and PGE2, failed to increase the phosphorylation, which is in agreement with the data showing that neither TNF nor IL-1 increased cAMP levels in PBMC. These results suggest that induction of phosphorylation of P65 and P74 by TNF and IL-1 is not mediated by PKC and PKA but may be mediated by another protein kinase and result in overlapping of biological activities between TNF and IL-1.

Contribution of IL-6 to the antiproliferative effect of IL-1 and tumor necrosis factor on tumor cell lines

The role of IL-6 in the antiproliferative effect of IL-1 for tumor cell lines was investigated using IL-1-sensitive cell lines. Human recombinant IL-1 alpha and IL-6 both inhibited the growth of an IL-1-sensitive cloned human melanoma cell line (A375-C6). However, IL-1 has greater maximum growth inhibitory activity than IL-6. Conditioned medium of the tumor cells that were treated with IL-1 contained IL-6 as determined by ELISA. Northern blot analysis revealed that IL-6 mRNA expression increased in IL-1-treated cells. In addition, antibody against human IL-6 neutralized about 50% of the antiproliferative effect of IL-1. The growth of an IL-1-resistant clone of A375 cells (A375-C5), which cannot be shown to express any detectable IL-1R, was inhibited by IL-6 to the same degree as A375-C6 cells. The A375-C5 cell line did not produce IL-6 or increase IL-6 mRNA after stimulation with IL-1. These results indicate that IL-6 mediates in part the antiproliferative effect of IL-1 on A375-C6 cells by acting as an autocrine antiproliferative factor. IL-1 also inhibited the growth of a malignant human mammary cell line (MDA-MB-415). IL-6 exhibited only slight growth inhibition in this cell line. Neither IL-6 production nor IL-6 mRNA expression was induced in this cell line by IL-1. Antibody against IL-6 did not neutralize the antiproliferative effect of IL-1. Therefore, for MDA-MB-415 cells IL-6 appeared not to be involved in the antiproliferative effect of IL-1. These results indicate that the antiproliferative effect of IL-1 involves at least two pathways, one IL-6 dependent and another IL-6 independent. The contribution of IL-6 to the antiproliferative effect of TNF was also examined. IL-6 appeared not to play a role in the antiproliferative effect of TNF in these cell lines.

Contribution of IL-6 to the antiproliferative effect of IL-1 and tumor necrosis factor on tumor cell lines

The role of IL-6 in the antiproliferative effect of IL-1 for tumor cell lines was investigated using IL-1-sensitive cell lines. Human recombinant IL-1 alpha and IL-6 both inhibited the growth of an IL-1-sensitive cloned human melanoma cell line (A375-C6). However, IL-1 has greater maximum growth inhibitory activity than IL-6. Conditioned medium of the tumor cells that were treated with IL-1 contained IL-6 as determined by ELISA. Northern blot analysis revealed that IL-6 mRNA expression increased in IL-1-treated cells. In addition, antibody against human IL-6 neutralized about 50% of the antiproliferative effect of IL-1. The growth of an IL-1-resistant clone of A375 cells (A375-C5), which cannot be shown to express any detectable IL-1R, was inhibited by IL-6 to the same degree as A375-C6 cells. The A375-C5 cell line did not produce IL-6 or increase IL-6 mRNA after stimulation with IL-1. These results indicate that IL-6 mediates in part the antiproliferative effect of IL-1 on A375-C6 cells by acting as an autocrine antiproliferative factor. IL-1 also inhibited the growth of a malignant human mammary cell line (MDA-MB-415). IL-6 exhibited only slight growth inhibition in this cell line. Neither IL-6 production nor IL-6 mRNA expression was induced in this cell line by IL-1. Antibody against IL-6 did not neutralize the antiproliferative effect of IL-1. Therefore, for MDA-MB-415 cells IL-6 appeared not to be involved in the antiproliferative effect of IL-1. These results indicate that the antiproliferative effect of IL-1 involves at least two pathways, one IL-6 dependent and another IL-6 independent. The contribution of IL-6 to the antiproliferative effect of TNF was also examined. IL-6 appeared not to play a role in the antiproliferative effect of TNF in these cell lines.

Determination of the secondary structure of interleukin-8 by nuclear magnetic resonance spectroscopy

The solution conformation of interleukin-8 (IL-8), a small protein of 72 residues with a wide range of proinflammatory activities, has been investigated by two-dimensional NMR spectroscopy. The 1H-NMR spectrum of IL-8 is assigned in a sequential manner and regular elements of secondary structure are identified on the basis of a qualitative interpretation of the nuclear Overhauser, coupling constant and amide exchange data. The IL-8 monomer contains a triple stranded anti-parallel beta-sheet arranged in a Greek key and a long C-terminal helix (residues 57-72). It is shown that IL-8 is a dimer in solution in which the interface is principally formed by six backbone hydrogen bonds between residues 25, 27, and 29 of one monomer and residues 29, 27, and 25, respectively, of the other. As a result, the two units of the dimer form a contiguous six-stranded anti-parallel beta-sheet. The secondary structure of IL-8 is similar to that found in the crystal structure of the sequence related protein platelet factor 4.