Stimulation of macrophage antibody-dependent killing of tumor targets by recombinant lymphokine factors and M-CSF

Macrophage colony-stimulating factor (M-CSF) was investigated as a stimulator of ADCC to the murine R1.1 thymoma target by murine peritoneal exudate macrophages which were elicited by proteose peptone. Both an 125IUdR release and a viable cell count assay were used. The latter assay avoids radiation damage, and the fate of the targets can be determined over a long period. Pretreatment of macrophages for several days in culture with lymphokine (LK) from concanavalin A-induced mouse spleen cells moderately stimulated ADCC. Preincubation of macrophages with conventional or recombinant human M-CSF or immunoaffinity-purified mouse M-CSF alone had little effect. However, M-CSF greatly enhanced ADCC to the tumor target when used as a costimulant with LK, IFN-gamma, IFN-alpha, IFN-beta, or IL-2 to pretreat macrophages. Incubation of macrophages with LK or LK plus M-CSF for 2 days generated stronger ADCC than 1- or 3-day incubations. Enhancement of LK-stimulated ADCC by M-CSF appeared to plateau at about 1000 U/ml. The enhancement of macrophage cytotoxicity when stimulated with IFNs or IL-2 was most effective at the lowest active concentration of these LKs. At 1 U/ml IFN-gamma or IL-2, or 5 U/ml IFN-alpha or IFN-beta, M-CSF boosted ADCC activity to that using 10-fold of the LK alone. IL-1, IL-4, and TNF had little or no stimulating activity for ADCC alone or with M-CSF, and the other hemopoietic growth factors IL-3 and GM-CSF did not promote this effector function alone or with IFN-gamma. We previously showed that M-CSF boosted macrophage antibody-independent killing of TU5 sarcoma targets with or without LK (Cell. Immunol. 105, 270, 1987). These studies thus show that M-CSF is a positive regulator of both macrophage-nonspecific tumor lysis and ADCC.     

Release of reactive nitrogen intermediates and reactive oxygen intermediates from mouse peritoneal macrophages. Comparison of activating cytokines and evidence for independent production

The capacity of 12 cytokines to induce NO2- or H2O2 release from murine peritoneal macrophages was tested by using resident macrophages, or macrophages elicited with periodate, casein, or thioglycollate broth. Elevated H2O2 release in response to PMA was observed in resident macrophages after a 48-h incubation with IFN-gamma, TNF-alpha, TNF-beta, or CSF-GM. Of these, only IFN-gamma induced substantial NO2- secretion during the culture period. The cytokines inactive in both assays under the conditions tested were IL-1 beta, IL-2, IL-3, IL-4, IFN-alpha, IFN-beta, CSF-M, and transforming growth factor-beta 1. Incubation of macrophages with IFN-gamma for 48 h in the presence of LPS inhibited H2O2 production but augmented NO2- release, whereas incubation in the presence of the arginine analog NG-monomethylarginine inhibited NO2- release but not H2O2 production. Although neither TNF-alpha nor TNF-beta induced NO2- synthesis on its own, addition of either cytokine together with IFN-gamma increased macrophage NO2- production up to six-fold over that in macrophages treated with IFN-gamma alone. Moreover, IFN-alpha or IFN-beta in combination with LPS could also induce NO2- production in macrophages, as was previously reported for IFN-gamma plus LPS. These data suggest that: 1) tested as a sole agent, IFN-gamma was the only one of the 12 cytokines capable of inducing both NO2- and H2O2 release; 2) the pathways leading to secretion of H2O2 and NO2- are independent; 3) either IFN-gamma and TNF-alpha/beta or IFN-alpha/beta/gamma and LPS can interact synergistically to induce NO2- release.     

Effect of interleukin-1 on the augmentation of human immunodeficiency virus gene expression

Among the cytokines tested here (IL-2, IL-3, IL-4, IL-5, IL-6, granulocyte colony stimulating factor (G-CSF), granulocyte/macrophage colony stimulating factor (GM-CSF), interferon-alpha (IFN-alpha), interferon-beta (IFN-beta) and interferon-gamma (IFN-gamma] only interleukin 1(IL-1) augmented HIV-long terminal repeat(LTR) directed chloramphenicol acetyl transferase(CAT) activity in protein kinase C(PKC)-independent manner. However, a stimulation by IL-1 was not as efficient as that due to tumor necrosis factor and the HIV production was not significant. IL-1 was not cytotoxic to MOLT-4/HIV cells.     

Effect of cytokines and growth factors on the macrophage colony-stimulating factor secretion by human bone marrow stromal cells

We have investigated the effect of growth factors, inflammatory and anti-inflammatory cytokines on the macrophage colony-stimulating factor (M-CSF) secretion by cultured human bone marrow stromal cells. Their production of M-CSF cultured in serum-free medium is enhanced in a time-dependent manner in response to tumour necrosis factor (TNF-)alpha and interleukin (IL-)4 but not to IL-1, IL-3, IL-6, IL-7, IL-10, SCF, granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF, bFGF and transforming growth factor (TGF-)beta. The co-addition of IL-4 and TNF-alpha has a greater than additive effect on the secretion of M-CSF suggesting that they act synergistically. The anti-inflammatory molecules IL-10 and TGF-beta have no effect on the TNF-alpha-induced M-CSF synthesis by marrow stromal cells. In conclusion TNF-alpha and IL-4 are potent stimulators of the M-CSF synthesis by human bone marrow stromal cells, a result of importance regarding the role of M-CSF in the proliferation/differentiation of mononuclear-phagocytic cells and the role of marrow stromal cells as regulators of marrow haematopoiesis.     

Gene expression and antiviral activity of alpha/beta interferons and interleukin-29 in virus-infected human myeloid dendritic cells

Dendritic cells (DCs) respond to microbial infections by undergoing phenotypic maturation and by producing multiple cytokines. In the present study, we analyzed the ability of influenza A and Sendai viruses to induce DC maturation and activate tumor necrosis factor alpha (TNF-alpha), alpha/beta interferon (IFN-alpha/beta), and IFN-like interleukin-28A/B (IFN-lambda2/3) and IL-29 (IFN-lambda1) gene expression in human monocyte-derived myeloid DCs (mDC). The ability of influenza A virus to induce mDC maturation or enhance the expression of TNF-alpha, IFN-alpha/beta, interleukin-28 (IL-28), and IL-29 genes was limited, whereas Sendai virus efficiently induced mDC maturation and enhanced cytokine gene expression. Influenza A virus-induced expression of TNF-alpha, IFN-alpha, IFN-beta, IL-28, and IL-29 genes was, however, dramatically enhanced when cells were pretreated with IFN-alpha. IFN-alpha priming led to increased expression of Toll-like receptor 3 (TLR3), TLR7, TLR8, MyD88, TRIF, and IFN regulatory factor 7 (IRF7) genes and enhanced influenza-induced phosphorylation and DNA binding of IRF3. Influenza A virus also enhanced the binding of NF-kappaB to the respective NF-kappaB elements of the promoters of IFN-beta and IL-29 genes. In mDC IL-29 induced MxA protein expression and possessed antiviral activity against influenza A virus, although this activity was lower than that of IFN-alpha or IFN-beta. Our results show that in human mDCs viruses can readily induce the expression of IL-28 and IL-29 genes whose gene products are likely to contribute to the host antiviral response.     

Increased human immunodeficiency virus (HIV) expression in chronically infected U937 cells upon in vitro differentiation by hydroxyvitamin D3: roles of interferon and tumor necrosis factor in regulation of HIV production.

We have investigated the roles of cytokines in the modulation of human immunodeficiency virus (HIV) production in chronically infected U937 cells upon in vitro differentiation by hydroxyvitamin D3. HIV-infected U937 cells exhibited markedly lower levels of CD4 and HLA-DR antigens than uninfected cells did. Vitamin D3 induced a time-dependent macrophagelike differentiation, as determined by monitoring the expression of some surface antigens by means of the monoclonal antibodies OKM1, OKM5, OKM13, OKM14, OKT4, anti-HLA-DR, TecMG2, TecMG3, LeuM3, LeuM1, anti-HLA-DP, and anti-HLA-DQ. Treatment with hydroxyvitamin D3 resulted in a marked increase in HIV production compared with control cultures. Interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) were detected in the culture media, whereas interferon (IFN) was not generally found. Using the polymerase chain reaction technique, we found HIV-infected U937 cells to express detectable levels of mRNAs for alpha interferon (IFN-alpha), IFN-beta, TNF-alpha, and IL-1 beta. The addition of TNF resulted in a marked increase of HIV production, whereas IL-1 beta was ineffective. In contrast, both IFN-alpha and IFN-beta exerted some inhibitory effect on HIV production, which was more marked in vitamin D3-treated cultures than in untreated cultures. HIV production was significantly increased by antibodies to IFN-alpha in both untreated and vitamin D3-treated cultures. Anti-IFN-beta antibody increased HIV production only in vitamin D3-treated cells. In contrast, anti-TNF-alpha antibodies markedly decreased HIV production in both control and differentiating U937 cells. Vitamin D3 treatment resulted in a higher expression of TNF receptors in differentiating cells than in control HIV-infected cells. These data demonstrate a strong correlation between HIV production and macrophagelike differentiation in chronically infected U937 cells and suggest that endogenous IFN and TNF exert opposite effects in the regulation of virus production in both undifferentiated and vitamin D3-treated cell cultures.     

Virus infection activates IL-1 beta and IL-18 production in human macrophages by a caspase-1-dependent pathway.

Monocytes and macrophages play a significant role in host's defense system, since they produce a number of cytokines in response to microbial infections. We have studied IL-1 beta, IL-18, IFN-alpha/beta, and TNF-alpha gene expression and protein production in human primary monocytes and GM-CSF-differentiated macrophages during influenza A and Sendai virus infections. Virus-infected monocytes released only small amounts of IL-1 beta or IL-18 protein, whereas 7- and 14-day-old GM-CSF-differentiated macrophages readily produced these cytokines. Constitutive expression of proIL-18 was seen in monocytes and macrophages, and the expression of it was enhanced during monocyte/macrophage differentiation. Expression of IL-18 mRNA was clearly induced only by Sendai virus, whereas both influenza A and Sendai viruses induced IL-1 beta mRNA expression. Since caspase-1 is known to cleave proIL-1 beta and proIL-18 into their mature, active forms, we analyzed the effect of a specific caspase-1 inhibitor on virus-induced IL-1 beta and IL-18 production. The release of IL-1 beta and IL-18, but not that of IFN-alpha/beta or TNF-alpha, was clearly blocked by the inhibitor. Our results suggest that the cellular differentiation is a crucial factor that affects the capacity of monocytes/macrophages to produce IL-1 beta and IL-18 in response to virus infections. Furthermore, the virus-induced activation of caspase-1 is required for the efficient production of biologically active IL-1 beta and IL-18.     

TRAF6 and MEKK1 play a pivotal role in the RIG-I-like helicase antiviral pathway

Type I interferons (IFN-alpha/beta) are essential for immune defense against viruses and induced through the actions of the cytoplasmic helicases, RIG-I and MDA5, and their downstream adaptor molecule IPS-1. TRAF6 and the downstream kinase TAK1 have been shown to be essential for the production of proinflammatory cytokines through the TLR/MyD88/TRIF pathway. Although binding of TRAF6 with IPS-1 has been demonstrated, the role of the TRAF6 pathway in IFN-alpha/beta production has not been fully understood. Here, we demonstrate that TRAF6 is critical for IFN-alpha/beta induction in response to viral infection and intracellular double-stranded RNA, poly(I:C). Activation of NF-kappaB, JNK, and p38, but not IRF3, was impaired in TRAF6-deficient mouse embryo fibroblasts in response to vesicular stomatitis virus and poly(I:C). However, TAK1 was not required for IFN-beta induction in this process, since normal IFN-alpha/beta production was observed in TAK1-deficient mouse embryo fibroblasts. Instead, another MAP3K, MEKK1, was important for the activation of the IFN-beta promoter in response to poly(I:C). Forced expression of MEKK1 in combination with IRF3 was sufficient for the induction of IFN-beta, whereas suppression of MEKK1 expression by small interfering RNA inhibited the induction of IFN-beta by poly(I:C). These data suggest that IPS-1 requires TRAF6 and MEKK1 to activate NF-kappaB and mitogen-activated protein kinases that are critical for the optimal induction of type I interferons.     

Inhibition of B cell receptor-mediated apoptosis by IFN.

IFNs are a family of cytokines that are involved in the regulation of immune and inflammatory responses. Clinical use of IFN-alpha/beta encompasses treatment for a variety of diseases; however, prolonged exposure to IFN-alpha/beta results in elevated levels of autoreactive Abs. In this study, we investigated the potential of IFNs to modulate apoptotic signals in B cells. We demonstrate that IFN-alpha or IFN-beta inhibit Ag receptor-mediated apoptosis in a dose-dependent manner. Inhibition of phosphatidylinositol 3' (PI3)-kinase did not abolish the effect of IFN, indicating that the antiapoptotic mechanism is PI3-kinase- and protein kinase B/Akt-independent. Instead, IFN-alpha and IFN-beta, but not IFN-gamma, significantly increase the levels of the survival protein Bcl-2, and to a lesser extent, Bcl-xL expression. Thus, IFN-alpha/beta-mediated inhibition of B cell Ag receptor-triggered apoptosis may offer a model for the process that leads to the escape of self-reactive B cells from negative selection and consequently results in autoantibody production.     

The effects of infection of thermal injury by Pseudomonas aeruginosa PAO1 on the murine cytokine response.

Pseudomonas aeruginosa infection, one of the major complications of burn wounds, may lead to sepsis and death. Using the Multi-Probe Template/RNase protection assay, we have compared the expression of different cytokine genes within the skin and livers of thermally injured mice infected with P. aeruginosa PAO1. Thermal injury alone enhanced or up-regulated certain cytokines, including macrophage colony-stimulating factor (M-CSF), interleukin 1 (IL-1)RI, IL-1 beta, macrophage inflammatory protein (MIP)-1 beta and MIP-2; while PAO1 challenge alone up-regulated tumour necrosis factor alpha (TNF-alpha) and transforming growth factor beta (TGF-beta) expression. The combination of thermal injury plus PAO1 infection enhanced the expression of several pro-inflammatory and haematopoietic cytokines [stem cell factor (SCF), leukocyte inhibitory factor (LIF), IL-6 and TNF-alpha]; induced the expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) and G-CSF by 5 h and the expression of additional cytokines, including TGF-beta, TNF-beta, lymphotoxin beta (LT-beta), interferon gamma (IFN-gamma), and IFN-beta by 40 h post-burn/infection. While the most intense cytokine expression occurred in the skin, the majority of cytokines tested were also expressed in the liver by 40 h post-burn/infection. These results suggest that in P. aeruginosa infection of burn wounds: (1) up-regulation of the expression of different cytokines, locally and within the livers of burned mice, is an indication of P. aeruginosa -induced sepsis; and (2) IL-6 and G-CSF play an important role in the host response mechanism.     

Interleukin-2 and alpha/beta interferon down-regulate hepatitis B virus gene expression in vivo by tumor necrosis factor-dependent and -independent pathways.

We have recently reported that administration of recombinant tumor necrosis factor alpha (TNF-alpha) to hepatitis B virus (HBV) transgenic mice reduces the hepatic steady-state content of HBV-specific mRNA by up to 80% in the absence of liver cell injury. In the current study, we analyzed the regulatory effects of several other inflammatory cytokines in the same transgenic model system. Hepatic HBV mRNA content was reduced by up to 90% following administration of a single noncytopathic dose (100,000 U) of interleukin 2 (IL-2). Comparable effects were produced by administration of alpha and beta interferons (IFN-alpha and IFN-beta), but only after multiple injections of at least 500,000 U per mouse. Importantly, the regulatory effect of IL-2 was completely blocked by the prior administration of antibodies to tumor necrosis factor alpha (TNF-alpha), which did not block the effect of IFN-alpha or IFN-beta. In contrast to these observations, recombinant IFN-gamma, IL-1, IL-3, IL-6, TNF-beta, transforming growth factor beta, and granulocyte-monocyte colony-stimulating factor were inactive in this system. These results suggest that selected inflammatory cytokines can down-regulate HBV gene expression in vivo by at least two pathways, one that is dependent on TNF-alpha and another that is not. These results imply that antigen-nonspecific products of the intrahepatic HBV-specific inflammatory response may contribute to viral clearance or persistence during HBV infection.     

Type I IFN induced IL1-Ra expression in hepatocytes is mediated by activating STAT6 through the formation of STAT2: STAT6 heterodimer

The biological activities of type I interferons (IFNs) are mediated by their binding to a heterodimer receptor complex (IFNAR1 and IFNAR2), resulting in the activation of the JAK (JAK1 and TYK2)-STAT (1, 2, 3, 5 isotypes) signalling pathway. Although several studies have indicated that IFN-alpha and IFN-beta can activate complexes containing STAT6, the biological role of this activation is still unknown. We found that exposure of hepatoma cells (HuH7 and Hep3B) to IFN-alpha or IFN-beta led to the activation of STAT6. Activated STAT6 in turn induced the formation of STAT2: STAT6 complexes, which led to the secretion of IL-1Ra. The activation of STAT6 by type I IFN in hepatocytes was mediated by JAK1 and Tyk2. In addition, IFN-alpha or IFN-beta significantly enhanced the stimulatory effect of IL-1beta on production of IL-1Ra. The present study suggests a novel function of IFN-alpha and IFN-beta signalling in human hepatocytes. Our results provide evidence for the mechanism how IFN-alpha and IFN-beta modulate inflammatory responses through activation of STAT6 and production of secreted IL-1Ra.     

Induction of cytokines in human peripheral blood mononuclear cells by mycoplasmas.

Various species of mycoplasmas were tested for their ability to induce cytokine production in human peripheral blood mononuclear cells (PBMC). Human PBMC were incubated with Mycoplasma pneumoniae, M. hyorhinis, M. arginini, M. salivarium, M. orale, M. gallisepticum or A. laidlawii for 48 hr, and the activities of interleukin-1 beta (IL-1 beta), IL-2, IL-4, IL-6, tumor necrosis factor-alpha (TNF-alpha) and interferon (IFN) in the supernatants were determined by ELISA or bioassay. All mycoplasma species induced IL-1 beta, IL-6 and TNF-alpha, although IL-2 was induced only by M. pneumoniae. IFN was induced by 5 of the 7 species, and the IFN produced was antigenically confirmed to be mainly IFN-alpha. On the other hand, mycoplasma-stimulated cultures did not contain detectable amounts of IFN-beta and IL-4 activities. Furthermore, the cytokines were induced by mycoplasmal contaminating cells in human PBMC as well as by mycoplasma alone. These results suggest that many kinds of cytokines induced by mycoplasma contamination in cell culture affect immunological experiments in vitro.     

Acute ethanol administration profoundly alters poly I:C-induced cytokine expression in mice by a mechanism that is not dependent on corticosterone

Polyinosinic polycytidylic acid (poly I:C) is an analog of double stranded RNA, which is a common replication intermediate for many viruses. It acts through a toll-like receptor (TLR3) to induce a group of cytokines that can mediate host resistance to viruses and some cancers. The effect of ethanol (EtOH) on induction of this set of cytokines has not been determined. Mice were treated with a single dose of EtOH (by gavage) at the same time as poly I:C was administered (intraperitoneally), and cytokine mRNA expression was measured by RNAse protection assay. Concentrations of IFN-alpha, IL-10, and IL-12 in the serum were measured by ELISA. A single dose of EtOH suppressed induction of mRNA for IFN-alpha, IFN-beta, IFN-gamma, IL-6, IL-9, IL-12, and IL-15. The concentrations of IFN-alpha and IL-12 in the serum were also decreased. In contrast, IL-10 was minimally induced by poly I:C alone, but it was substantially induced by poly I:C plus EtOH. Dose response and time course studies demonstrated that significant alterations of IFN-alpha, IL-10, and IL-12 expression occurred at dosages as low as 4 g/kg (a dosage previously shown to produce blood EtOH concentrations of approximately 0.2%) and that alterations persisted at least 4-6 hr after administration of EtOH. The glucocorticoid synthesis inhibitor, aminoglutethimide, diminished corticosterone levels to normal, but did not block the effects of EtOH on cytokine expression. These results demonstrate that EtOH affects the expression of poly I:C-induced cytokines and that this action is not mediated by corticosterone. These results plus previously published findings are consistent with the idea that EtOH may be a generalized suppressor of toll-like receptor signaling.     

Virus-induced interferon alpha/beta (IFN-alpha/beta) production by T cells and by Th1 and Th2 helper T cell clones: a study of the immunoregulatory actions of IFN-gamma versus IFN-alpha/beta on functions of different T cell populations

Spleen cells, resting T cells, activated T cells, and T cell clones characterized as type 1 (Th1) and type 2 (Th2) were investigated for their ability to produce interferon (IFN) following in vitro culture with Newcastle disease virus (NDV). All of the above cell populations, including both Th1 and Th2 T cell clones, produced high levels of IFN following in vitro culture with NDV. This IFN was characterized as a mixture of IFN-alpha and IFN-beta with IFN-alpha being the predominate species of IFN contained in the mixture. IL-2 greatly enhanced the production of IFN-alpha/beta by all cell populations in response to NDV. These different T cell populations responded very differently to the immunoregulatory actions of IFN-gamma versus IFN-alpha/beta. IFN-alpha/beta was shown to be a potent inhibitor of Con A or IL-2-induced proliferation of different T cell populations. This inhibition was not associated with a reduction in lymphokine production since spleen cells or Th1 T cell clones cultured with Con A and IFN-alpha/beta had no decrease in IL-2 or IFN-gamma production when compared to Con A-stimulated control cultures. IFN-gamma had little to no inhibitory activity on Con A-induced proliferation of spleen cells. In fact, Con A-induced proliferation was usually enhanced by IFN-gamma when nylon wool-enriched T cells were assessed. Different results were observed when IFN-gamma and IFN-alpha/beta were investigated for their ability to inhibit IL-2-induced proliferation of different T helper cell clones. IFN-gamma and IFN-alpha/beta were both capable of inhibiting IL-2-induced proliferation of T cell clones characterized as type 2 (Th2). In contrast, IFN-gamma had no effect on IL-2-induced proliferation of Th1 clones. IFN-alpha/beta, however, inhibited IL-2-induced proliferative responses of both Th1 and Th2 T cell clones. These results document the facts that (1) IFN-gamma and IFN-alpha/beta differ in their immunoregulatory actions, (2) different T cell subpopulations vary in their susceptibility to IFN-gamma regulation, and (3) virus induction of IFN-alpha/beta appears to be a ubiquitous function associated with different T cell populations.     

Activation of macrophages for ADCC in vitro: effects of IL-4, TNF, interferons-alpha/beta, interferon-gamma, and GM-CSF.

Macrophages in varying states of activation differ in their ability to perform antibody-dependent cellular cytotoxicity (ADCC) and antibody-independent macrophage-mediated tumor cytotoxicity (MTC). To define further the activation requirements for macrophages to perform various cytolytic functions, we stimulated peptone-elicited peritoneal macrophages, which are only poorly cytolytic, with one of a panel of cytokines and then quantified three distinct cytolytic capacities. The peptone-elicited macrophages, after stimulation with IFN-alpha/beta, IL-4, or TNF, had increased ability to perform both the rapid and slow variants of ADCC but not to perform MTC. Stimulation with high doses of IFN-gamma, however, increased the macrophages' ability to perform all three cytolytic functions. GM-CSF had no effects on any cytolytic capacity. The effects of IL-4, TNF, IFN-gamma, and IFN-alpha/beta on the macrophages' capacity for both forms of ADCC were dose-dependent. IFN-gamma and IFN-alpha/beta increased the macrophages' capacity for both variants of ADCC within 4 hr of treatment, whereas IL-4 and TNF did so only after prolonged treatment. These results suggest that three forms of macrophage cytolytic capacity can be enhanced by cytokine treatment but that the requirements for enhancing each of the three forms of macrophage cytolytic capacity differ.     

Modulation by biologic response modifiers of hepatitis C virus antigen-independent cytokine secretion in blood mononuclear cells.

The systemic hepatitis C virus (HCV) antigen-non-specific cytokine responses were investigated in cultures of peripheral blood mononuclear cells. Cytokines of the T helper (Th) 1 [interferon (IFN)gamma and interleukin (IL)-2] and Th2 (IL-4 and IL-10) phenotype, and the pro-inflammatory cytokines tumour necrosis factor alphaIL-1beta and IL-6, were secreted by the cells activated by the HCV antigen-independent pathway. Furthermore, these cytokine responses were shifted towards a Th1 predominance by treatment with IFN-beta and with IL-2, whereas cytokine responses were selectively amplified towards a combined Th1-Th2 profile by granulocyte-macrophage- but not by macrophage colony-stimulating factor. Moreover, pro-inflammatory cytokine production was significantly enhanced by IFN-beta and augmented dose-dependently with GM-CSF and IL-2. Therefore, these immune mediators can promote unique-as well as overlapping-systemic cytokine responses that may be relevant for immunotherapeutic interventions to control HCV infection.     

Vascular hyperpermeability induced by tumor necrosis factor and its augmentation by IL-1 and IFN-gamma is inhibited by selective depletion of neutrophils with a monoclonal antibody

We investigated whether various recombinant cytokines induce vascular hyperpermeability when intradermally injected into rats. Only TNF did so. Of the other cytokines examined (IL-1, IL-2, granulocyte-CSF, IFN-alpha, IFN-beta, IFN-gamma) none had this effect. The increase in vascular permeability was dose dependent, and the peak response was observed at 90 min after TNF injection. When mixtures of TNF and various other cytokines (IL-1, IL-2, granulocyte-CSF, IFN-alpha, IFN-beta, IFN-gamma) were injected, only IL-1 and IFN-gamma augmented TNF-induced vascular hyperpermeability, the increase occurring in a dose-dependent manner. The induction of vascular hyperpermeability by TNF and its enhancement by IL-1 and IFN-gamma were inhibited by selective depletion of peripheral blood neutrophils with i.p. administration of an anti-rat neutrophil mAb, RP-3. Reconstitution of neutrophils to the depleted rats by in situ injection of these cells, restored TNF increased vascular permeability.