Identification and characterization of macrophage inflammatory protein 2

Characterization of the promoter of the human gene encoding the high-affinity IgG receptor: transcriptional induction by gamma-interferon is mediated through common DNA response elements

Expression of the high-affinity receptor for IgG (Fc gamma RI) is restricted to cells of myeloid lineage and is induced by gamma-interferon (IFN-gamma) but not by IFN-alpha/beta. The organization of the human Fc gamma RI gene has been determined and the DNA elements governing its cell type-restricted transcription and IFN-gamma induction are reported here. A 39-nucleotide sequence (IFN-gamma response region, or GRR) is defined that is both necessary and sufficient for IFN-gamma inducibility. Sequence analysis of the GRR reveals the presence of promoter elements initially defined for the major histocompatibility complex class II genes: i.e., X, H, and gamma-IRE sequences. Comparison of a number of genes whose expression is induced selectively by IFN-gamma indicates that the presence of these elements is a general feature of IFN-gamma-responsive genes. Our studies suggest that the combination of X, H, and gamma-IRE elements is a common motif in the pathway of transcriptional induction by this lymphokine.

Antitumor effector mechanism of interleukin-1 beta at a distant site in the double grafted tumor system

Recombinant human interleukin-1 beta (IL-1 beta) inhibited the growth of not only the right, but also the left non-treated tumor in a double grafted tumor system. Since the antitumor activity of IL-1 beta against the right and left tumors was not seen in nude mice, lymphocytes have a key role in the antitumor effect of intratumoral administration of IL-1 beta. TIL (tumor-infiltrating leukocytes) obtained from left and right side tumors treated with IL-1 beta were examined by Winn assay for their antitumor activity against Meth-A sarcoma in BALB/c mice. TIL from the right side clearly inhibited the growth of admixed Meth-A cells, but control TIL did not. Spleen cells and right and left regional lymph node cells prepared from IL-1-treated mice were examined for Lyt-1, Lyt-2 and L3T4 phenotypes. The number of Lyt-1-positive lymphocytes increased in the spleen and in the right regional lymph nodes after intratumoral administration of IL-1. Isolated tumor cells obtained from the right tumor treated with IL-1 beta and the left side tumor on day 6 were cultured in RPMI 1640 with 10% fetal calf serum for 24 h. The culture supernatants were harvested and tested for the presence of chemotactic activity for neutrophils or macrophages. Significant neutrophil chemotactic factor and macrophage chemotactic factor activities were detected in the culture media from IL-1-treated tumor tissues cultured for 24 h. Neither significant neutrophil nor macrophage chemotactic activity was detected in the media from untreated tumor tissues. These results suggest that intratumoral administration of IL-1 first induces neutrophils and macrophages in the right tumor, then Lyt-1-positive cells in the right regional lymph nodes and in the spleen, and subsequently induces macrophages in the left, non-treated tumor.

IL-1 and TNF-alpha induction of IL-8 and monocyte chemotactic and activating factor (MCAF) mRNA expression in a human astrocytoma cell line

In order to elucidate the role of inflammatory cytokines in the central nervous system (CNS), we examined whether IL and TNF-alpha induce cells in the CNS to produce two newly identified leucocyte chemo-attractants, IL-8 and monocyte chemotactic and activating factor (MCAF). Several human astrocytoma and glioblastoma cell lines expressed high levels of IL-8 and MCAF mRNA in vitro upon stimulation with IL-1 and TNF-alpha. In particular, an astrocytoma cell line U373MG subclone responded markedly to IL-1 with high expression levels of IL-8 and MCAF mRNA as well as IL-6 mRNA. Both IL-8 and MCAF mRNA expression depended on the dose of IL-1 and appeared as early as 30 min to 1 hr after IL-1 stimulation, confirming that these are early inducible genes. The production of IL-8 and MCAF in the U373MG cell culture supernatants was confirmed by a competitive radioimmunoassay (RIA) as well as chemotactic activities on human neutrophils and monocytes. IL-1-induced IL-8 and MCAF mRNA expression appeared to occur at least at the transcriptional level as revealed by a nuclear run-off assay. Moreover, IL-1 treatment increased the half-life of IL-8 and MCAF mRNA markedly, suggesting that increased mRNA stability was also responsible for the enhanced gene transcription. These data suggest that IL-1 and TNF-alpha induce astrocytes to produce IL-8 and MCAF transcriptionally and post-transcriptionally, both of which may be responsible for leucocytosis seen in inflammation of the CNS.

Crystal structure of interleukin 8: symbiosis of NMR and crystallography

The crystal structure of a host defense system chemotactic factor, interleukin 8, has been solved by molecular replacement using as a model the solution structure derived from nuclear magnetic resonance experiments. The structure was refined with 2 A x-ray data to an R factor of 0.187 (0.217 at 1.6 A). A comparison indicates some potential differences between the structure in solution and in the crystalline state. Our analysis also predicts that residues 4 through 9 on the amino terminus and the beta-bend, which includes His-33, may be important for receptor binding.

PDGF and the small inducible gene (SIG) family: roles in the inflammatory response

A growing body of evidence suggests that cells responding to an initial growth, inflammatory or immune signal can respond by inducing the transcription of selective members of the SIG family. This family of related inducible cytokines are involved in the amplification, propagation and coordination of intercellular communication among cell types involved in the immune and inflammatory responses. The principal anti-inflammatory action of glucocorticoids may involve the transcriptional and translational inhibition of cytokines such as JE and other members of the SIG family to effectively disrupt the normal lines of intercellular communication which normally coordinates the immune and inflammatory response. The identification of new members of the family and the discovery of the functions of the known members will lead to a clearer understanding of the complicated processes which lead to normal and pathological immune and inflammatory responses.

Antitumor effect of PSK at a distant site: inductions of interleukin-8-like factor and macrophage chemotactic factor in murine tumor

The antitumor effect of PSK, a Coriolus preparation, at a distant site was analyzed with the use of a double grafted tumor system in which male BALB/c mice received simultaneous intradermal inoculations of Meth-A tumor in the right (10(6) cells) and the left (2 x 10(5) cells) flanks and were then injected with PSK in the right tumor on the third day thereafter. The antitumor effect of intratumoral administration of PSK in the right tumor on days 3, 4 and 5 was compared with the effect of surgical resection of the right tumor on day 5. Three out of 8 mice given PSK intratumorally became tumor-free whereas no mouse tumor-free in the left flank was found among the surgically resected mice. As regards sinecomitant immunity, tumor inoculation into the right flank followed by intra-tumoral administration of PSK on days 3 and 5 and surgical excision of the primary tumor on day 6 resulted in complete rejection of a tumor challenge in the left flank on day 21. The combination of presurgical intratumoral injections of PSK (more than 2 times) and postoperative oral administration of PSK appeared to be most effective in eradicating secondary tumors. Isolated TILs (tumor-infiltrating lymphocytes), obtained from the right tumor (treated with PSK) and the left tumor on day 10 in the double grafted tumor system were cultured in RPMI1640 with 10% fetal calf serum for 24 h. The culture supernatants were harvested and tested for the presence of chemotactic activity for neutrophils or macrophages. Significant neutrophil chemotactic factor (NCF) and macrophage chemotactic factor (MCF) activities were detected in the culture media from PSK-treated TILs that had been cultured for 24 h. Neither significant neutrophil nor macrophage chemotactic activity was detected in the media from untreated TILs. NCF and MCF activities were also detected in the culture supernatant from PSK-treated tumor tissue on day 6. PSK-induced NCF in the murine tumor was neutralized by treatment with anti-human IL-8 IgG, and might be murine IL-8-like factor. Therefore, neutrophil and macrophage infiltrations of tumors following intratumoral injections of PSK are probably mediated by inductions of IL-8-like factor and MCF.

Isolation and characterization of a macrophage-derived heparin-binding growth factor

Human mononuclear cells were plated in culture, and the conditioned media of these cells were analyzed by heparin-Sepharose affinity chromatography. The fractions were tested for growth factor activity as measured by the stimulation of DNA synthesis in BALB/c 3T3 cells. After 2 d in culture, two peaks of heparin-binding growth factor (HBGF) activity were detected, one eluting with 0.5 M NaCl, which could be shown to be platelet-derived growth factor (PDGF)-like, and the other eluting with 1.0 M NaCl. After 7-11 d in culture, when monocytes had clearly differentiated into macrophages, greater than 95% of the HBGF activity in conditioned medium consisted of the 1.0 M NaCl elution peak. This activity, which was designated macrophage-derived HBGF (MD-HBGF), was found to be a cationic heat-resistant polypeptide with a molecular weight in the range of 14-25 kDa. Analysis using Western blots and specific neutralizing antisera, as well as comparative heparin affinity analysis, indicated that MD-HBGF was not identical to other heparin-binding 3T3 cell growth factors known to be produced by macrophages, such as PDGF (AB, AA, and BB forms), acidic fibroblast growth factor, and basic fibroblast growth factor. In addition to stimulating mitogenesis in 3T3 cells, MD-HBGF also stimulated the proliferation of vascular smooth muscle cells, but did not stimulate the proliferation of vascular endothelial cells.

Identification of three related human GRO genes encoding cytokine functions

The product of the human GRO gene is a cytokine with inflammatory and growth-regulatory properties; GRO is also called MGSA for melanoma growth-stimulatory activity. We have identified two additional genes, GRO beta and GRO gamma, that share 90% and 86% identity at the deduced amino acid level with the original GRO alpha isolate. One amino acid substitution of proline in GRO alpha by leucine in GRO beta and GRO gamma leads to a large predicted change in protein conformation. Significant differences also exist in the 3' untranslated region, including different numbers of ATTTA repeats associated with mRNA instability. A 122-base-pair region in the 3' region is conserved among the three GRO genes, and a part of it is also conserved in the Chinese hamster genome, suggesting a role in regulation. DNA hybridization with oligonucleotide probes and partial sequence analysis of the genomic clones confirm that the three forms are derived from related but different genes. Only one chromosomal locus has been identified, at 4q21, by using a GRO alpha cDNA clone that hybridized to all three genes. Expression studies reveal tissue-specific regulation as well as regulation by specific inducing agents, including interleukin 1, tumor necrosis factor, phorbol 12-myristate 13-acetate, and lipopolysaccharide.

The neutrophil-activating proteins interleukin 8 and beta-thromboglobulin: in vitro and in vivo comparison of NH2-terminally processed forms

Isolation of the human neutrophil activating protein (NAP) interleukin 8 (IL8) from leukocytes has revealed that it is structurally related to beta-thromboglobulin (beta TG) from platelets. Both these proteins occur as natural mixtures of multiple forms, differing from each other by unequal truncation at the NH2 terminus. In this study we have compared IL8 and beta TG forms for in vitro and in vivo neutrophil activation. In contrast to IL8, none of the beta TG forms were found to exert granulocyte chemotactic activity in vitro, as measured in the agarose assay. However, fractions rich in the most extensively processed forms of beta TG (e.g. NAP-2) as well as pure NAP-2 did induce lactoferrin release from granulocytes, whereas fractions containing only the longer forms (e.g. connective tissue-activating peptide III) were inactive. In order to observe this in vitro effect, about 10-fold less IL8 (10 nM) than NAP-2 was required. In the presence of a vasodilator substance low doses (2-20 pmol) of IL8 and the shorter forms of beta TG caused granulocyte accumulation and plasma leakage in rabbit skin whereas the longer forms of beta TG again failed to do so. Finally, granulocytosis induction following i.v. injection was found to occur with NAP-2. At the maximal dose tested (250 pmol), this in vivo effect of NAP-2 was less pronounced than that of IL8. In the case of IL8, NH2-terminal processing did not seem to affect granulocyte stimulatory activity. It should be noted, however, that the extent of processing of IL8 is less than that occurring with beta TG. It can be concluded that the platelet factor beta TG, structurally related to the monokine IL8, can also play a role in neutrophil activation during inflammatory reactions.

Cloning and characterization of cDNAs for murine macrophage inflammatory protein 2 and its human homologues

A cDNA clone of murine macrophage inflammatory protein 2 (MIP-2) has been isolated from a library prepared from lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and the nucleotide sequence determined. This cDNA was used to clone cDNAs for human homologues of MIP-2 from a library prepared from phorbol myristate acetate-treated and LPS-stimulated U937 cells. Two homologues were isolated and sequenced. Human MIP-2 alpha and MIP-2 beta are highly homologous to each other and to a previously isolated gene, human gro/melanoma growth-stimulating activity (MGSA). These three human genes, MIP-2 alpha, MIP-2 beta, and gro/MGSA, constitute a sub-family within the cytokine family represented by platelet factor 4 and interleukin 8.

A macrophage mRNA selectively induced by gamma-interferon encodes a member of the platelet factor 4 family of cytokines

In order to identify novel mediators synthesized in activated macrophages, a cDNA library was prepared from cultures of the mouse macrophage cell line RAW 264.7 that had been treated with lymphokine-rich conditioned medium from mitogen-stimulated mouse spleen cells. Differential plaque hybridization identified a cDNA, designated m119, that detected a 1.6-kilobase mRNA that accumulated in response to gamma-interferon (IFN-gamma) but not in response to other macrophage activators, including IFN-alpha, IFN-beta, and lipopolysaccharide. The mRNA encoded a predicted protein of Mr 14,461 containing a 21-amino acid signal peptide. The primary structure of the predicted protein indicated that it is a member of a recently described family of cytokines related to platelet factor 4, including Gro/melanoma growth stimulatory activity and neutrophil-activating peptide/interleukin 8. The selective induction of the m119 mRNA by IFN-gamma that the predicted m119 protein mediates a macrophage activity regulated by IFN-gamma. The m119 protein may be a cytokine that affects the growth, movement, or activation state of cells that participate in immune and inflammatory responses. It is proposed that the gene encoding this protein be called mig, for monokine induced by gamma interferon.

Lipopolysaccharide-stimulated human monocytes secrete, apart from neutrophil-activating peptide 1/interleukin 8, a second neutrophil-activating protein. NH2-terminal amino acid sequence identity with melanoma growth stimulatory activity

Purification of monocyte-derived NAP-1/IL-8 by preparative reversed-phase (RP)-HPLC led to the detection of a second peak with polymorphonuclear leukocyte (PMNL)-activating (degranulation, chemotaxis) properties. The monokine responsible for this biological activity, which we tentatively termed NAP-3, could be purified to homogeneity by three different RP-HPLC steps. Tricine-SDS-PAGE analysis gave a single line at Mr 5.3 kD (NAP-1/IL-8 = 5.8 kD). NH2-terminal amino acid sequence analysis read as a major sequence (ASVATELRXCXLQT. .), which shows greater than 40% homology to that of NAP-1/IL-8. The sequence is identical to that found for the 13-kD moiety of melanoma growth stimulating activity (MGSA) and the product of the oncogene gro. Determination of neutrophil chemotactic activity of NAP-3 revealed a typical bell-shaped dose-response curve (ED50 = 2 ng/ml) with no significant neutrophil chemotactic activity at doses greater than 200 ng/ml. Also, in cytochalasin B-pretreated PMNL, NAP-3 elicited release of myeloperoxidase and beta-glucuronidase. Crossdesensitization studies in PMNL enzyme release revealed crossreactivities with the NAP-1/IL-8-R on PMNL. NAP-3 (MGSA/gro) appears to represent the first member of the novel supergene family of beta-thromboglobulin-like host defense cytokines, which expresses both mitogenic as well as proinflammatory properties at the nanogram level.

Identification and characterization of an inhibitor of haemopoietic stem cell proliferation

The haemopoietic system has three main compartments: multi-potential stem cells, intermediate stage progenitor cells and mature cells. The availability of simple reproducible culture systems has made possible the characterization and purification of regulators of the progenitor cells, including colony-stimulating factors and interleukins. In contrast, our knowledge of the regulators involved in the control of stem cell proliferation is limited. The steady-state quiescent status of the haemopoietic stem cell compartment is thought to be controlled by locally acting regulatory elements present in the stromal microenvironment, but their purification has been hampered by the lack of suitable culture systems. We have recently developed a novel in vitro colony assay that detects a primitive cell (CFU-A) which has similar proliferative characteristics, in normal and regenerating bone marrow, to the CFU-S (haemopoietic stem cells, as defined by the spleen colony assay) and which responds to CFU-S-specific proliferation regulators. We have now used this assay to purify to homogeneity a macrophage-derived reversible inhibitor of haemopoietic stem cell proliferation (stem cell inhibitor, SCI). Antibody inhibition and sequence data indicate that SCI is identical to a previously described cytokine, macrophage inflammatory protein-1 alpha (MIP-1 alpha), and that SCI/MIP-1 alpha is functionally and antigenically identical to the CFU-S inhibitory activity obtained from primary cultures of normal bone marrow cells. The biological activities of SCI/MIP-1 alpha suggest that it is a primary negative regulator of stem cell proliferation and that it has important therapeutic applications in protecting haemopoietic stem cells from damage during cytotoxic therapies for cancer.

Localization of 9E3/CEF-4 in avian tissues: expression is absent in Rous sarcoma virus-induced tumors but is stimulated by injury

The avian gene 9E3/CEF-4, a member of the superfamily of genes that includes KC and gro, is expressed abundantly in exponentially growing cultures of chick embryo fibroblasts (CEFs) and at high levels in CEFs transformed with Rous sarcoma virus (RSV). The product of this gene is a secreted protein that has homologies and structural similarities to inflammatory mediators. The function of 9E3 is obscure and its expression in vivo has not yet been investigated. We studied by in situ hybridization and RNA blots the pattern of 9E3 mRNA distribution in the wings of normal, wounded, and RSV-infected newly hatched chicks. We found that the message for 9E3 is high in specific tissues in normal wings; whereas connective tissue, tendon, and bone express the gene, muscle fibers, endothelium, epidermis, and bone marrow do not. The distribution coincides with that of interstitial collagen. Wounding results in marked elevation of the mRNA within the granulation tissue formed during healing and in adjacent tissues, especially those showing neovascularization. Similar elevation of mRNA occurs immediately adjacent to RSV tumors but, surprisingly, the tumor tissue itself shows no detectable levels of this message. Cells explanted from the tumors and grown in culture also show no expression of 9E3, in marked contrast to the very high level found in similarly cultured RSV-transformed CEFs. These results show that there are intrinsic differences between transformed embryonic cells in tissue culture and RSV target cells in the hatched chick. However, the expression of the gene in the periphery of tumors leaves open the possibility that 9E3 may still be involved in RSV carcinogenesis. The abundant expression of 9E3 in normal tissues indicates that the product of this gene plays a normal physiological role in tissues growing by cell division, perhaps as a growth regulator. The elevated expression of 9E3 in areas of neovascularization, makes it possible that the product of this gene could act as an angiogenic factor. Finally, expression in conjunction with high collagen levels and in wounded tissues may point to a role in wound response and/or repair, possibly via alteration of extracellular matrix.

Generation of the neutrophil-activating peptide NAP-2 from platelet basic protein or connective tissue-activating peptide III through monocyte proteases

We studied the origin of the neutrophil-activating peptide NAP-2, a presumed 70 amino acid cleavage product of platelet basic protein (PBP) and connective tissue-activating peptide III (CTAP-III). Purified human blood monocytes or lymphocytes were cultured with or without stimuli (LPS or PHA) in the presence or absence of platelet-release supernatant, and the formation of NAP-2 and other neutrophil-activating peptides was monitored. NAP-2 was generated whenever monocytes and platelet release supernatant were present. When a monocyte stimulus was added, NAF/NAP-1 was also formed, and in the presence of LPS a third, less potent neutrophil-stimulating fraction, consisting of NAP-2 variants with 73, 74, and 75 residues, also appeared. Monocytes alone did not yield NAP-2 and no neutrophil-activating peptide was generated by lymphocytes. The monocyte-conditioned medium was found to cleave purified CTAP-III into NAP-2 through proteinases that were highly sensitive to PMSF, moderately sensitive to leupeptin and insensitive to EDTA.

The role of cytokines in the generation of inflammation and tissue damage in experimental gram-positive meningitis

Cytokines mediate many host responses to bacterial infections. We determined the inflammatory activities of five cytokines in the central nervous system: TNF-alpha, IL-1 alpha, IL-1 beta, macrophage inflammatory protein 1 (MIP-1), and macrophage inflammatory protein 2 (MIP-2). Using a rabbit model of meningeal inflammation, each cytokine (except IL-1 beta) induced enhanced blood brain barrier permeability, leukocytosis in cerebrospinal fluid, and brain edema. Homologous antibodies to each mediator inhibited leukocytosis and brain edema, and moderately decreased blood brain barrier permeability. In rabbits treated with anti-CD-18 antibody to render neutrophils dysfunctional for adhesion, each cytokine studied lost the ability to cause leukocytosis and brain edema. After intracisternal challenge with pneumococci, antibodies to TNF or IL-1 prevented inflammation, while anti-MIP-1 or anti-MIP-2 caused only a 2-h delay in the onset of inflammation. We suggest these cytokines have multiple inflammatory activities in the central nervous system and contribute to tissue damage during pneumococcal meningitis.

Identification by sequence analysis of chemotactic factors for monocytes produced by normal and transformed cells stimulated with virus, double-stranded RNA or cytokine

A monocyte chemotactic activity was found to be released by various types of cultured human cells after appropriate stimulation: normal diploid fibroblasts, peripheral blood mononuclear cells or monocytes isolated therefrom, and a number of tumor cell lines, including osteosarcoma (MG-63) and hepatoma (Malavu) but not melanoma (Bowes) cells. Cultures of diploid human fibroblasts and these tumor cells stimulated with interleukin (IL) 1 or double-stranded RNA [poly(rI).poly(rC)], or infected with viruses (measles or rubella viruses) were found to produce chemotactic activity for both monocytes and granulocytes. Media collected from fibroblasts treated with E. coli or IL 6 did not contain such activity. Granulocyte and monocyte chemotactic activities were serologically distinct, and could be separated by successive chromatographical procedures. While the granulocyte chemotactic activity of both fibroblasts and MG-63 cells had previously been identified as granulocyte chemotactic protein/IL 8, the monocyte chemotactic activity from MG-63 cells was identified by amino acid sequence analysis as a different protein recently described to be released by human glioma and myelomonocytic cell lines. In view of the similarity in their chromatographical behavior, monocyte chemotactic activities from fibroblasts, MG-63 cells and fresh monocytes can probably be assigned to identical molecules. Cultures of unfractionated peripheral blood cells, however, were found to release an additional monocyte chemotactic protein, identifiable by amino acid sequence analysis as platelet factor 4.

Myelopoietic enhancing effects of murine macrophage inflammatory proteins 1 and 2 on colony formation in vitro by murine and human bone marrow granulocyte/macrophage progenitor cells

Two recently identified and purified murine macrophage inflammatory proteins MIP-1 and MIP-2 were tested in vitro both alone, and in combination with purified recombinant (r) murine (mu) GM-CSF, natural (n)muCSF-1, or rhuman (hu)G-CSF, for effects on mouse marrow CFU-GM, in combination with erythropoietin for effects on mouse marrow BFU-E, and in combination with rhuGM-CSF or rhuG-CSF for effects on human marrow CFU-GM. MIP-1 and MIP-2 did not stimulate, but did enhance by up to threefold, colony formation of mouse CFU-GM co-stimulated by rmuGM-CSF and nmuCSF-1, but not by rhuG-CSF, in the absence or presence of serum. MIP-1 and MIP-2 were maximally active at concentrations greater than or equal to 100 ng/ml and the actions appeared to be initiated during the DNA synthetic portion of the cell cycle. Neither MIP-1 nor MIP-2 at up to 1 microgram/ml had any effect on mouse BFU-E, in the absence or presence of erythropoietin. Both MIP-1 and MIP-2 had direct acting effects on purified mouse CFU-GM. The cloning efficiency of 200 purified cells plated with 50 U muCSF-1 was 82% with and 43% without MIP; the cloning efficiency with 50 U rmuGM-CSF was 65% with and 35% without MIP. MIP effects were not mimicked by bacterial LPS, rhuIL-1 alpha, rhuIL-6, or rmuIL-4, and were neutralized by their respective specific antibodies. MIP-1 and MIP-2 also enhanced endogenously stimulated and rhuGM-CSF-, but not rhuG-CSF-, stimulated colony formation by human marrow CFU-GM. These results demonstrate a new role for MIP-1 and MIP-2 in vitro as myelopoietic enhancing activities for CFU-GM.

Effects of the neutrophil-activating peptide NAP-2, platelet basic protein, connective tissue-activating peptide III and platelet factor 4 on human neutrophils

Platelet basic protein (PBP), connective tissue-activating peptide III (CTAP-III), and platelet factor 4 (PF-4) were purified from human platelet release supernatants by heparin-Sepharose ion-exchange and reversed-phase HPLC, and their neutrophil-activating effects were compared with those of NAP-2, a peptide of 70 amino acids corresponding to part of the sequence of PBP (1) and with sequence homology to NAF/NAP-1. NAP-2-induced elastase release and a rise in cytosolic free Ca2+ at concentrations between 0.3 and 100 nM, and neutrophil chemotaxis at concentrations between 0.03 and 10 nM. It was half as potent as NAF/NAP-1 in inducing exocytosis but showed the same activity in the other responses. By contrast, only minimal if any effects were obtained with PBP, CTAP-III, and PF-4 up to 100 nM. NAP-2 thus appears to behave like a typical chemotactic receptor agonist. It could be generated from PBP and/or CTAP-III released from activated platelets and lead to the accumulation of neutrophils in platelet aggregates.

The chemotactic activity for granulocytes produced by virally infected fibroblasts is identical to monocyte-derived interleukin 8

So far, the role of fibroblasts in inflammatory processes has been underestimated. We have previously shown that stimulation of fibroblasts with viruses or bacteria results in a simultaneous production of several cytokines, including interferon-beta, interleukin (IL) 6 and colony-stimulating factors. We here report that virally infected fibroblasts produce also a chemotactic factor for granulocytes. The activity is inducible not only by measles virus but also by IL 1 beta and the double-stranded RNA poly(rI).poly(rC). This factor, when purified to homogeneity, occurs as a 6-7-kDa protein doublet upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The pure protein is serologically related to a fully characterized granulocyte chemotactic peptide (GCP) from monocytes, designated IL8. Furthermore, the chemotactic factor from fibroblasts has an NH2-terminal sequence identical to that of GCP/IL8, small differences in NH2-terminal processing being observed. Finally, in addition to diploid fibroblasts, the osteosarcoma MG-63 cell line is also a producer of GCP/IL8. It can thus be concluded that GCP/IL8 can be produced by several cell types in response to infection and that fibroblasts can contribute to chemotaxis in inflammation.