Administration of recombinant IL-12 to normal mice enhances cytolytic lymphocyte activity and induces production of IFN-gamma in vivo

IL-12 is a heterodimeric cytokine that has been shown to enhance natural killer (NK) and cytotoxic T lymphocyte (CTL) responses, and to induce IFN-gamma production in vitro. In this study, we have examined the effects in vivo of administering purified murine rIL-12 to normal mice. Daily injections of rIL-12 i.p. (1 ng to 10 micrograms/day) caused dose-dependent enhancement of NK cell lytic activity in the spleens and livers of treated mice. Histologic examination of the livers of IL-12-treated mice revealed focal mononuclear cell infiltrates, and flow cytometry studies indicated that the livers of IL-12-treated mice contained increased numbers of NK cells, CD8+ T cells, and monocytes. Liver and splenic lymphoid cells from IL-12-treated mice, unlike liver and splenic lymphoid cells from control mice, spontaneously secreted IFN-gamma in vitro, suggesting that they had been induced by IL-12 to produce IFN-gamma in vivo. Consistent with this, IFN-gamma could be detected in the serum of IL-12-treated mice. In mice which had been immunized by footpad injection of allogeneic splenocytes, daily administration of rIL-12 i.p. was shown to enhance the specific CTL response in the draining lymph nodes. Thus, these studies demonstrate that IL-12 can enhance NK and CTL activity and induce IFN-gamma production in vivo, as well as in vitro, and suggest possible mechanisms by which IL-12 may exert therapeutic effects in the treatment of some tumors and infectious diseases.

Anti-Inflammatory effects of antidepressants through suppression of the interferon-gamma/interleukin-10 production ratio

There is some evidence that major depression--in particular, treatment-resistant depression (TRD)--is accompanied by activation of the inflammatory response system and that proinflammatory cytokines may play a role in the etiology of depression. This study was carried out to examine the effects of antidepressive agents, i.e., imipramine, venlafaxine, L-5-hydroxytryptophan, and fluoxetine on the production of interferon-gamma (IFN-gamma), a proinflammatory cytokine, and interleukin-10 (IL-10), a negative immunoregulatory cytokine. Diluted whole blood of fluoxetine-treated patients with TRD (mean age, 50.6+/-3.9 years) and age-matched healthy controls (mean age, 51.6+/-1.7 years) and younger healthy volunteers (mean age, 35.4+/-9.6 years) was stimulated with phytohemagglutinin (1 microg/mL) and lipopolysaccharide (5 microg/mL) for 48 hours with and without incubation with the antidepressants at 10-6 M and 10(-5) M. IFN-gamma and IL-10 were quantified by means of enzyme-linked immunoassays. The ratio of IFN-gamma to IL-10 production by immunocytes was computed because this ratio is of critical importance in determining the capacity of immunocytes to activate or inhibit monocytic and T-lymphocytic functions. All four antidepressive drugs significantly increased the production of IL-10. Fluoxetine significantly decreased the production of IFN-gamma. All four antidepressants significantly reduced the IFN-gamma/IL-10 ratio. There were no significant differences in the antidepressant-induced changes in IFN-gamma or IL-10 between younger and older healthy volunteers and TRD patients. Tricyclic antidepressants, selective serotonin reuptake inhibitors, and serotonin-noradrenaline reuptake inhibitors, as well as the immediate precursor of serotonin, have a common, negative immunoregulatory effect by suppressing the IFN-gamma/IL-10 production ratio. It is suggested that the therapeutic efficacy of antidepressants may be related to their negative immunoregulatory effects.

Novel mode of action of c-kit tyrosine kinase inhibitors leading to NK cell-dependent antitumor effects

Mutant isoforms of the KIT or PDGF receptors expressed by gastrointestinal stromal tumors (GISTs) are considered the therapeutic targets for STI571 (imatinib mesylate; Gleevec), a specific inhibitor of these tyrosine kinase receptors. Case reports of clinical efficacy of Gleevec in GISTs lacking the typical receptor mutations prompted a search for an alternate mode of action. Here we show that Gleevec can act on host DCs to promote NK cell activation. DC-mediated NK cell activation was triggered in vitro and in vivo by treatment of DCs with Gleevec as well as by a loss-of-function mutation of KIT. Therefore, tumors that are refractory to the antiproliferative effects of Gleevec in vitro responded to Gleevec in vivo in an NK cell-dependent manner. Longitudinal studies of Gleevec-treated GIST patients revealed a therapy-induced increase in IFN-gamma production by NK cells, correlating with an enhanced antitumor response. These data point to a novel mode of antitumor action for Gleevec.

In vivo evidence for a functional role of both tumor necrosis factor (TNF) receptors and transmembrane TNF in experimental hepatitis

The significance of tumor necrosis factor receptor 1 (TNFR1) for TNF function in vivo is well documented, whereas the role of TNFR2 so far remains obscure. In a model of concanavalin A (Con A)-induced, CD4+ T cell-dependent experimental hepatitis in mice, in which TNF is a central mediator of apoptotic and necrotic liver damage, we now provide evidence for an essential in vivo function of TNFR2 in this pathophysiological process. We demonstrate that a cooperation of TNFR1 and TNFR2 is required for hepatotoxicity as mice deficient of either receptor were resistant against Con A. A significant role of TNFR2 for Con A-induced hepatitis is also shown by the enhanced sensitivity of transgenic mice overexpressing the human TNFR2. The ligand for cytotoxic signaling via both TNF receptors is the precursor of soluble TNF, i.e. transmembrane TNF. Indeed, transmembrane TNF is sufficient to mediate hepatic damage, as transgenic mice deficient in wild-type soluble TNF but expressing a mutated nonsecretable form of TNF developed inflammatory liver disease.

An Anti-IL-12p40 Antibody Down-Regulates Type 1 Cytokines, Chemokines, and IL-12/IL-23 in Psoriasis

Psoriasis is characterized by activation of T cells with a type 1 cytokine profile. IL-12 and IL-23 produced by APCs are essential for inducing Th1 effector cells. Promising clinical results of administration of an Ab specific for the p40 subunit of IL-12 and IL-23 (anti-IL-12p40) have been reported recently. This study evaluated histological changes and mRNA expression of relevant cytokines and chemokines in psoriatic skin lesions following a single administration of anti-IL-12p40, using immunohistochemistry and real-time RT-PCR. Expression levels of type 1 cytokine (IFN-gamma) and chemokines (IL-8, IFN-gamma-inducible protein-10, and MCP-1) were significantly reduced at 2 wk posttreatment. The rapid decrease of these expression levels preceded clinical response and histologic changes. Interestingly, the level of an anti-inflammatory cytokine, IL-10, was also significantly reduced. Significant reductions in TNF-alpha levels and infiltrating T cells were observed in high responders (improvement in clinical score, > or =75% at 16 wk), but not in low responders. Of importance, the levels of APC cytokines, IL-12p40 and IL-23p19, were significantly decreased in both responder populations, with larger decreases in high responders. In addition, baseline levels of TNF-alpha significantly correlated with the clinical improvement at 16 wk, suggesting that these levels may predict therapeutic responsiveness to anti-IL-12p40. Thus, in a human Th1-mediated disease, blockade of APC cytokines by anti-IL-12p40 down-regulates expression of type 1 cytokines and chemokines that are downstream of IL-12/IL-23, and also IL-12/IL-23 themselves, with a pattern indicative of coordinated deactivation of APCs and Th1 cells.

Treatment of depression is associated with suppression of nonspecific and antigen-specific T(H)1 responses in multiple sclerosis

OBJECTIVE

To examine the relationship between depression, treatment of depression, and interferon gamma (IFN-gamma) production by peripheral blood mononuclear cells in patients with comorbid diagnoses of relapsing-remitting multiple sclerosis (MS) and major depressive disorder.

DESIGN

A randomized comparative outcome trial of three 16-week treatments for depression. Assessments were conducted at baseline, week 8, and treatment cessation.

SETTING

An academic outpatient treatment and clinical research center.

PATIENTS

Fourteen patients who met the criteria for relapsing-remitting MS and major depressive disorder.

INTERVENTIONS

Individual cognitive behavioral therapy, group psychotherapy, or sertraline therapy.

MAIN OUTCOME MEASURES

Depression was assessed using the Beck Depression Inventory. Interferon gamma production by peripheral blood mononuclear cells was measured following stimulation with OKT3 or recombinant human myelin oligodendrocyte glycoprotein (MOG). Variability in immune assays was controlled using 8 nondepressed healthy subjects who were enrolled at times corresponding with the enrollment of MS patients.

RESULTS

Results of the Beck Depression Inventory were significantly related to IFN-gamma production stimulated with OKT3 or MOG at baseline (P< or = .03 for all). Level of depression, OKT3-stimulated IFN-gamma production, and MOG-stimulated IFN-gamma production all declined significantly over the 16-week treatment period (P< or = .03 for all). Among controls, there were no significant changes over time in OKT3- or MOG-stimulated IFN-gamma, or in depression (P> or = .25 for all).

CONCLUSIONS

These findings suggest that the production of the proinflammatory cytokine IFN-gamma by autoaggressive T cells in relapsing-remitting MS is related to depression and that treatment of depression may decrease IFN-gamma production. Thus, treatment of depression may provide a novel disease-modifying therapeutic strategy as well as a symptomatic treatment for patients with MS.

FcgammaRIII-dependent inhibition of interferon-gamma responses mediates suppressive effects of intravenous immune globulin

Intravenous immune globulin (IVIG) suppresses autoantibody-mediated inflammation by inducing and activating the inhibitory Fc receptor FcgammaRIIb and downstream negative signaling pathways. We investigated the effects of IVIG on cellular responses to interferon-gamma (IFN-gamma), a potent macrophage activator that exacerbates inflammation. Our study showed that IVIG blocked IFN-gamma signaling and IFN-gamma-induced gene expression and suppressed IFN-gamma function in vivo during immune responses to Listeria monocytogenes and in an IFN-gamma-enhanced model of immune thrombocytopenic purpura. The mechanism of inhibition of IFN-gamma signaling was suppression of expression of the IFNGR2 subunit of the IFN-gamma receptor. The inhibitory effect of IVIG was mediated at least in part by soluble immune complexes and was dependent on FcgammaRIII but independent of FcgammaRIIb. These results reveal an unexpected inhibitory role for the activating FcgammaRIII in mediating suppression of IFN-gamma signaling and suggest that inhibition of macrophage responses to IFN-gamma contributes to the anti-inflammatory properties of IVIG.

An agonist of adenosine A3 receptors decreases interleukin-12 and interferon-gamma production and prevents lethality in endotoxemic mice

We have recently observed that the selective adenosine A3 receptor agonist N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA) augments interleukin-10 and inhibits tumor necrosis factor-alpha production in endotoxemic mice. In the present study, we extended our investigations into the effect of this compound on the bacterial lipopolysaccharide (endotoxin)-induced inflammatory response in the BALB/c, as well as in the C57BL/6 interleukin-10+/+ and the interleukin-10 deficient C57BL/6 interleukin-10(0)/0 mice strains. In the BALB/c mice, i.p. pre-treatment with IB-MECA (0.2 and 0.5 mg/kg) decreased lipopolysaccharide (60 mg/kg i.p.)-induced plasma levels of interleukin-12 (p40 and p70), interferon-gamma, and nitrite/nitrate (breakdown products of nitric oxide (NO)). On the other hand, pre-treatment with this compound failed to influence lipopolysaccharide-induced plasma interleukin-1 alpha, interleukin-6, and corticosterone concentrations. Similar to its effect in BALB/c mice, IB-MECA enhanced the release of interleukin-10 in the C57BL/6 interleukin-10+/+ mice. Furthermore, IB-MECA inhibited the production of interleukin-12, interferon-gamma, and NO in both the C57BL/6 interleukin-10+/+ and C57BL/6 interleukin-10(0)/0 mice, suggesting that the inhibition of pro-inflammatory cytokine production by this compound is independent of the increased release of interleukin-10. Finally, pre-treatment with this compound protected mice against lipopolysaccharide (60 mg/kg i.p.)-induced lethality. These results indicate that stimulation of adenosine A3 receptors has potent anti-inflammatory effects and may represent a potential strategy in the treatment of septic shock and other inflammatory diseases.

Combined spinal and general anesthesia attenuates liver metastasis by preserving TH1/TH2 cytokine balance

BACKGROUND

Many studies have shown that regional anesthesia improves postoperative outcome and particularly lessens infection by attenuating perioperative immunosuppression related to the stress response to surgery and general anesthesia. However, it remains to be determined whether regional anesthesia improves oncologic outcome after surgery.

METHODS

C57BL/6 mice were subjected to laparotomy during sevoflurane general anesthesia alone or combined with spinal block achieved with bupivacaine (5 microg) and morphine (1.25 microg). Control groups were anesthetized only or were untreated. Liver was removed 5 h after surgery to assess antitumor killer cell activity and production of interferon gamma and interleukin 4 by liver mononuclear cells, or mice were inoculated intravenously with liver-metastatic EL4 cells and hepatic metastases were counted 12 days later.

RESULTS

Laparotomy during sevoflurane anesthesia significantly increased the number (+/- SD) of liver metastases from 15.5 +/- 8.7 (control) and 19.4 +/- 5.4 (sevoflurane alone) to 33.7 +/- 8.9. Sevoflurane anesthesia plus spinal block significantly reduced this increase to 19.8 +/- 9. The in vitro killer activity of liver mononuclear cells against EL4 cells decreased from 32.7% (control) and 29.4% (sevoflurane alone) to 18.5% after sevoflurane plus laparotomy, and the addition of spinal block increased activity to 26.6%. The interferon-gamma/interleukin-4 ratio decreased from 89.3 (control) and 95.7 (anesthesia alone) to 15.7 after sevoflurane plus laparotomy, and the addition of spinal block increased the ratio to 46.5.

CONCLUSIONS

The addition of spinal block to sevoflurane general anesthesia accompanying surgery attenuates the suppression of tumoricidal function of liver mononuclear cells, presumably by preserving the T helper 1/T helper 2 (Th1/Th2) balance, and thereby reduces the promotion of tumor metastasis.

The enzyme indoleamine 2,3-dioxygenase is induced in the mouse brain in response to peripheral administration of lipopolysaccharide and superantigen

The essential amino-acid, L-tryptophan, is the precursor of serotonin. Its availability in the brain is controlled by indoleamine 2,3-dioxygenase (IDO). This enzyme is inducible by cytokines such as interferon-gamma (IFN-gamma) and is the first and rate-limiting enzyme of the catabolism pathway of tryptophan. Since induction of IDO has been proposed to mediate the influence of cytokines on mood in patients with various somatic disorders, the present study aimed at analyzing the relationships between changes in brain IDO activity and serum IFN-gamma levels in response to peripheral immune stimulation by lipopolysaccharide (LPS) and superantigen in mice. Each of these treatments induced an increase in serum IFN-gamma at 6 h post-treatment followed 24 h later by a two-fold increase in IDO activity in the brain. These results support the involvement of peripheral IFN-gamma in the control of L-tryptophan catabolism in the brain.

The flavonoid, quercetin, differentially regulates Th-1 (IFNgamma) and Th-2 (IL4) cytokine gene expression by normal peripheral blood mononuclear cells

Flavonoids are plant metabolites that are dietary antioxidants and exert significant anti-tumor, anti-allergic, anti-inflammatory and anti-viral effects. It is generally accepted that Th-1 derived cytokines such as IL-2, IFNgamma and IL-12 promote cellular immunity while Th-2 derived cytokines such as IL-4, IL-5, IL-6 exert negative immunoregulatory effects on cellular immunity while upregulating humoral immunity. The molecular mechanisms underlying the biological activities of flavonoids have not been elucidated. We hypothesize that the flavonoid, quercetin, exert significant anti-viral and anti-tumor effects possibly by modulating the production of Th-1 and Th-2 derived cytokines. Peripheral blood mononuclear cells (PBMC, 1 x 10(6) cells/ml) from normal subjects were cultured with different concentrations of quercetin (0.5-50 microM) for 24-72 h and supernates were quantitated for IFN-gamma and IL-4 by ELISA and antiviral activity of IFNgamma by bioassay. FACS analysis was done to determine the number of IFN-gamma and IL-4 positive cells and RT-PCR was done to quantitate gene expression. Quercetin significantly induces the gene expression as well as the production of Th-1 derived IFNgamma and the downregulates Th-2 derived IL-4 by normal PBMC. Further, quercetin treatment increased the phenotypic expression of IFNgamma cells and decreased IL-4 positive cells by FACS analysis, which corroborate with protein secretion and gene expression studies. These results suggest that the beneficial immuno-stimulatory effects of quercetin may be mediated through the induction of Th-1 derived cytokine, IFNgamma, and inhibition of Th-2 derived cytokine, IL-4.

Diagnosis of Mycobacterium bovis infection in cattle by use of the gamma-interferon (Bovigam®) assay

The strategic use of the gamma-interferon (IFN-gamma) assay (Bovigam) can provide a means for the early identification of Mycobacterium bovis infected cattle, thus ensuring their removal from an infected herd. When used in parallel with the tuberculin test, it is capable of identifying infected cattle, which might otherwise not be detected until later, if at all. The early detection and removal of these animals reduces the risk that they will become a source of infection for other cattle. When targeted in herds of high prevalence the benefits to the herd owner directly concerned can be considerable as the assay provides a means of shortening the period of restriction for such herds. This serves to generate confidence among herd owners and other stakeholders that effective schemes, based on sound scientific principles, can be developed to eradicate tuberculosis from infected cattle populations.

Effects of administration of progenipoietin 1, Flt-3 ligand, granulocyte colony-stimulating factor, and pegylated granulocyte-macrophage colony-stimulating factor on dendritic cell subsets in mice

We studied the effects of administration of several cytokines, including progenipoietin-1 (ProGP-1), Flt-3 ligand (FL), granulocyte colony-stimulating factor (G-CSF), and granulocyte-macrophage colony-stimulating factor in a pegylated form (pGM-CSF), on dendritic cell (DC) populations in mouse spleen. ProGP-1 produced the most striking increase in overall DC numbers, apparently more than its constituent FL and G-CSF components. However, the expansion in DC numbers was strongly subpopulation selective, with ProGP-1 and FL producing selective expansion of CD8+ DCs, whereas pGM-CSF produced selective expansion of CD8- DCs. Surprising differences were observed between the effects of murine and human recombinant FL preparations on murine DCs. Many of the biologic functions of the DC subpopulations expanded by cytokines remained intact, including the capacity of the ProGP-1- and FL-expanded CD8+ DCs to produce the T-helper-1-biasing cytokine interleukin 12 (IL-12). However, the expanded DCs from all but G-CSF-treated mice were deficient in the ability to make interferon gamma, and the CD8+ DCs produced with pGM-CSF treatment had an abrogated capacity to form bioactive IL-12. Such selective expansion of DC populations and alterations in their cytokine-secretion capacity have implications for clinical use of the studied cytokines in immune modulation.

Reduced interferon gamma production by antigen-stimulated cord blood mononuclear cells is a risk factor of allergic disorders--6-year follow-up study

BACKGROUND

It is not sufficient to predict 'high allergic risk newborns' on the basis of increased IgE concentrations of cord blood alone, because a raised cord blood IgE concentration is specific but not sensitive in the prediction of the development of allergic disorders. Warner et al. have reported that interferon gamma (IFN-gamma) production by allergen-triggered cord blood cells is a predictor of atopic eczema, based on the 1-year follow-up study.

OBJECTIVE

We examined whether IFN-gamma production by antigen-stimulated cord blood mononuclear cells (CBMCs) is a risk factor of allergic disorders, based on the 6-year follow-up study.

METHODS

The relationships among cord blood IgE concentrations, IFN-gamma and interleukin-2 (IL-2) productions by antigen-stimulated CBMCs, and the development of allergic disorders in 21 infants for 6 years were investigated.

RESULTS

Atopic dermatitis, atopic dermatitis and allergic rhinitis, or atopic dermatitis and bronchial asthma developed in seven of 21 subjects. The maximal IFN-gamma concentration in culture supernatants of ovalbumin (OA) or bovine serum albumin (BSA) stimulated CBMCs in infants who developed allergic disorders was significantly lower (P < 0.01) than that in infants who did not develop any allergic disorders. In contrast, the maximal IL-2 concentration in culture supernatants of OA- or BSA-stimulated CBMCs in infants who developed allergic disorders was not lower than in infants who did not develop any allergic disorders. Moreover, the IFN-gamma concentrations were negatively correlated with cord blood IgE concentrations.

CONCLUSION

Reduced IFN-gamma production by antigen-stimulated CBMCs is a risk factor of allergic disorders.

Control of memory CD4 T cell recall by the CD28/B7 costimulatory pathway

The CD28/B7 costimulatory pathway is generally considered dispensable for memory T cell responses, largely based on in vitro studies demonstrating memory T cell activation in the absence of CD28 engagement by B7 ligands. However, the susceptibility of memory CD4 T cells, including central (CD62L(high)) and effector memory (T(EM); CD62L(low)) subsets, to inhibition of CD28-derived costimulation has not been closely examined. In this study, we demonstrate that inhibition of CD28/B7 costimulation with the B7-binding fusion molecule CTLA4Ig has profound and specific effects on secondary responses mediated by memory CD4 T cells generated by priming with Ag or infection with influenza virus. In vitro, CTLA4Ig substantially inhibits IL-2, but not IFN-gamma production from heterogeneous memory CD4 T cells specific for influenza hemagglutinin or OVA in response to peptide challenge. Moreover, IL-2 production from polyclonal influenza-specific memory CD4 T cells in response to virus challenge was completely abrogated by CTLA4Ig with IFN-gamma production partially inhibited. When administered in vivo, CTLA4Ig significantly blocks Ag-driven memory CD4 T cell proliferation and expansion, without affecting early recall and activation. Importantly, CTLA4Ig treatment in vivo induced a striking shift in the phenotype of the responding population from predominantly T(EM) in control-treated mice to predominantly central memory T cells in CTLA4Ig-treated mice, suggesting biased effects of CTLA4Ig on T(EM) responses. Our results identify a novel role for CD28/B7 as a regulator of memory T cell responses, and have important clinical implications for using CTLA4Ig to abrogate the pathologic consequences of T(EM) cells in autoimmunity and chronic disease.

Comparison of the effects of interleukin-1 alpha, interleukin-1 beta and interferon-gamma-inducing factor on the production of interferon-gamma by natural killer

Interferon-gamma inducing factor (IGIF) is a recently identified cytokine which stimulates the production of interferon-gamma (IFN-gamma) by T cells and enhances natural killer (NK) cell cytolytic activity. Protein fold recognition, structure prediction and comparative modeling have revealed that IGIF is a member of the interleukin (IL)-1 cytokine family and has prompted the designation IL-1 gamma. Here we report functional similarities between members of the IL-1 family by comparing the effects of IL-1 alpha, IL-1 beta and IGIF on NK cell production of IFN-gamma. All three IL-1 types enhanced NK cell production of IFN-gamma when induced by IL-2 or IL-12, although at high concentrations (> 10 ng/ml), IGIF was five- to tenfold more potent than IL-1 alpha or IL-1 beta. This effect correlated with enhanced levels of mRNA for IFN-gamma when NK cells were stimulated with IGIF plus IL-12. In contrast to IL-12 and IL-2, the ability of IGIF to stimulate NK cell production of IFN-gamma was not increased by IL-1 alpha or IL-1 beta. The ability of IGIF to enhance IFN-gamma production was independent of the type I and type II IL-1 receptors or the IL-1R accessory protein. Together, these results identify IGIF as a potent stimulator of NK cell production of IFN-gamma and demonstrate that the effect of IGIF on NK cell production of IFN-gamma is similar to that of IL-1 alpha and IL-1 beta but distinct from that of IL-12.

The low-toxicity versions of LPS, MPL adjuvant and RC529, are efficient adjuvants for CD4+ T cells

Lipopolysaccharide (LPS) has long been known to enhance innate and adaptive immune responses; however, its extreme toxicity precludes its use in clinical settings. The combined toxicity and adjuvanticity of LPS have contributed to the view that immunological adjuvants need to be highly inflammatory to be maximally effective. Here, we compared the effects of LPS with its less-toxic derivatives, monophosphoryl lipid A (MPL) and a chemical mimetic, RC529, on CD4+ T cell clonal expansion, long-term survival, and T helper cell type 1 (Th1) differentiation. We found that LPS, MPL, and RC529 had similar effects on CD4+ T cell clonal expansion, cell division, and ex vivo survival. Analysis of the ability of activated CD4+ T cells to produce interferon-gamma following a 21-day immunization and challenge protocol with LPS and MPL resulted in similar Th1 differentiation. In contrast, we found that LPS was more effective in promoting long-term CD4+ T cell responses, as we recovered nearly sixfold more cells following immunization/challenge as compared with treatment with MPL. Our results indicate that low-inflammation adjuvants, such as MPL and RC529, are capable of enhancing short-term CD4+ T cell clonal expansion and Th1 differentiation, but inflammatory signaling aids in the long-term retention of antigen-specific T cells.

Efficient targeting of the IL-4 gene in a BALB/c embryonic stem cell line

Embryonic stem (ES) cell lines have been derived from the inner cell mass of day 3.5 blastocysts of the inbred mouse strain BALB/cJ. Twenty-three lines were karyotyped and three were selected for injection into C57BL/6J host blastocysts. Two of the three lines, BALB/c-I and BALB/c-IV, produced germ-line chimaeras. The suitability of the BALB/c-I line for gene targeting experiments was tested by transfecting a targeting construct for the interleukin-4 (IL-4) gene. Transfected BALB/c-I cells exhibited efficient homologous recombination of the targeting vector and transmitted the induced mutation through the germline. This newly-characterized BALB/c-ES cell line thus provides an alternative to the traditional 129-derived and the recently described C57BL/6 embryonic stem cell lines, and will be useful in disrupting genes involved in the immune system. Furthermore, the genetically pure BALB/c IL-4 deficient mice will aid in studying the role of IL-4 in several infectious disease models in which the BALB/c mouse is a susceptible strain.

IL-15 enhances survival and function of HIV-specific CD8+ T cells

HIV-specific CD8(+) T cells are prone to undergo apoptosis, and this may affect their ability to control HIV infection. Because CD8-mediated immune responses play a key role in controlling HIV infection, enhancing the survival and effector function of HIV-specific CD8(+) T cells may augment their ability to control HIV virus. We show here that interleukin 15 (IL-15) potently inhibits spontaneous and CD95/Fas-induced apoptosis of HIV-specific CD8(+) T cells. IL-15 inhibits apoptosis in both CD45RA(-)CD62L(-) and CD45RA(+)CD62L(-) effector memory subpopulations of these cells. Furthermore, IL-15 greatly enhances the survival of HIV-specific CD8(+) T cells in long-term cultures. Finally, IL-15 directly enhances activation, interferon gamma (IFNgamma) production, and direct ex vivo cytotoxicity of HIV-specific CD8(+) T cells. Thus, IL-15 potently enhances the survival and effector function of HIV-specific CD8(+) T cells and, therefore, may prove useful in augmenting the antiviral function of these cells.

Effects of interferon-alpha on cytokine profile, T cell receptor repertoire and peptide reactivity of human allergen-specific T cells

A large panel of T cell clones (TCC) specific for the recombinant form of Poa pratensis allergen (rKBG7.2 or Poa p9) were established from the peripheral blood of grass pollen-sensitive donor in the absence or presence of recombinant interferon-alpha (IFN-alpha) in bulk culture and their pattern of cytokine secretion, peptide reactivity and TCR V beta repertoire was examined. The majority of allergen-specific TCC derived in absence of IFN-alpha produced high amounts of interleukin-4 (IL-4) and IL-5 but not IFN-gamma (Th2 cells), while most of TCC derived in presence of IFN-alpha produced IFN-gamma but not, or limited amounts of, IL-4 and IL-5 (Th1 or Th0 cells). Of 24 TCC established in the presence of IFN-alpha, 22 were able to recognize a single allergen peptide, p26, while none of the clones established in the absence of IFN-alpha showed a similar specificity. The majority of both clones expressed the V beta 2 element regardless of whether they were established in the presence of INF-alpha, but the presence of IFN-alpha favored the expansion of V beta 2+, V beta 17+ and V beta 22+ Poa p9-specific T cells, whereas in the absence of IFN-alpha, other TCR V beta-bearing T cells (V beta 5, and V beta 6.7, and V beta 14) were expanded in addition to V beta 2+ T cells. None of V beta 2+ clones established in the absence of IFN-alpha reacted with p26, whereas all the V beta 2+ clones established in its presence in the absence of interferon-alpha reacted with p26, whereas all the V beta 2+ clones established in its presence reacted to this peptide. IFN-alpha also shifted the TCR V beta repertoire of both Poa p9- and Lolium perenne group 1 (Lol p1)-specific T cell lines generated from the same patient and from a different grass-sensitive individual. These data demonstrate that IFN-alpha modulates the development of allergen-specific T cells in vitro, and suggest that IFN-alpha may represent a useful tool for novel immunotherapeutic approaches in allergic disorders.

Sterile protection of monkeys against malaria after administration of interleukin-12

An estimated 300-500 million new infections and 1.5-2.7 million deaths attributed to malaria occur annually in the developing world, and every year tens of millions of travelers from countries where malaria is not transmitted visit countries with malaria. Because the parasites that cause malaria have developed resistance to many antimalarial drugs, new methods for prevention are required. Intraperitoneal injection into mice of one dose of 150 ng (approximately 7.5 micrograms per kg body weight) recombinant mouse interleukin-12 (rmIL-12) 2 days before challenge with Plasmodium yoelii sporozoites protects 100% of mice against malaria. We report that one subcutaneous injection of 10 micrograms/kg recombinant human IL-12 (rhIL-12) 2 days before challenge with P. cynomolgi sporozoites protected seven of seven rhesus monkeys. Protection was associated with marked increases in plasma levels of interferon-gamma (IFN-gamma), and relative increases of lymphoid cell messenger RNA coding for IFN-gamma and several other cytokines. We speculate that rIL-12 protects monkeys through IFN-gamma-dependent elimination of P. cynomolgi-infected hepatocytes. This first report of rIL-12-induced protection of primates against an infectious agent supports assessment of rhIL-12 for immunoprophylaxis of human malaria.

IL-5 secretion by allergen-stimulated CD4+ T cells in primary culture: relationship to expression of allergic disease

BACKGROUND

IL-5-producing allergen-specific T cells are thought to play a prominent role in the pathogenesis of allergic inflammation. We hypothesized that T cell allergen-driven IL-5 synthesis is elevated in patients with atopic disease as compared with that in atopic patients free of disease and nonatopic control subjects.

OBJECTIVES

The purpose of this study was to compare IL-5 and interferon-gamma (IFN-gamma) secretion and proliferation by peripheral blood T cells from sensitized atopic patients with asthma, rhinitis, and no symptoms and from nonatopic control subjects in response to the allergen Dermatophagoides pteronyssinus (Der p) and the control recall antigen Mycobacterium tuberculosis purified protein derivative (PPD).

METHODS

To measure allergen-induced IL-5 production and proliferation, we developed a short-term culture technique that required a single antigenic stimulation of freshly isolated peripheral blood mononuclear cells (PBMC). With this technique, we measured Der p- and PPD-induced IL-5 production and proliferation in PBMC from atopic patients with asthma who were allergic to Der p, atopic patients with rhinitis, atopic patients with no symptoms, and a group of nonatopic normal control subjects. In four experiments, CD4+ or CD8+ T cells were depleted from PBMC to confirm that IL-5 synthesis was T cell dependent.

RESULTS

T cell IL-5 production, but not IFN-gamma production, in response to Der p was elevated in atopic patients with asthma and atopic patients with rhinitis compared with findings in atopic patients with no symptoms or nonatopic control subjects. IL-5 production was abrogated by depletion of CD4+, but not CD8+, T cells. In subjects with asthma, allergen-driven IL-5 production correlated with bronchial hyperreactivity. Allergen-induced proliferation was also higher in patients with asthma than in atopic subjects with no symptoms or nonatopic controls. T cell IL-5 and IFN-gamma production and proliferation in response to PPD were similar regardless of atopic status or disease.

CONCLUSIONS

Elevated IL-5 production is a characteristic of allergen-specific peripheral blood CD4+ T cells from sensitized patients with atopic disease but not atopy per se.

Therapeutic effect of erythromycin on influenza virus-induced lung injury in mice

Erythromycin (EM) is an antibiotic with potent antiinflammatory effects that is used for treating chronic lower respiratory tract infections. It has been shown that free radicals, such as the superoxide anion and nitric oxide (NO), are pathogenic molecules in viral disease. Much attention has been given to a critical role of NO in the pathologic events of various inflammatory diseases. In the present study, we evaluated the effects of EM on influenza-virus-induced pneumonia in mice infected with a lethal dose of influenza virus A/Kumamoto/Y5/67 (H2N2). The administration of EM at a dose of 3.3 mg/kg/d (intraperitoneally, from Days 1 to 6 after infection), significantly improved the survival rate of mice infected with influenza virus, and the survival rate of the virus-infected mice at Day 20 after infection increased in a dose-dependent fashion with EM administered to the animals, from 14% among controls to 42% among animals given EM at 1.0 mg/kg/d and 57% among those given EM at 3.3 mg/kg/d. The induction of interferon-gamma (IFN-gamma) in the mouse lung was inhibited by EM treatment on Day 6 after infection. Simultaneously, the number of inflammatory cells recovered in lung lavage fluid 6 d after virus infection was significantly reduced by the treatment with EM. The EM treatment resulted in a dose-dependent decrease in the level of nitrite/nitrate (metabolites of NO) in the serum and the NO synthase (NOS)-inducting potential in the lungs of the virus-infected mice. These results indicate that EM may have substantial therapeutic value for various acute inflammatory disorders such as influenza-virus-induced pneumonia, by inhibiting inflammatory-cell responses and suppressing NO overproduction in the lung.

Polarization of naive T cells into Th1 or Th2 by distinct cytokine-driven murine dendritic cell populations: implications for immunotherapy

Dendritic cells (DCs) activate T cells and regulate their differentiation into T helper cell type 1 (Th1) and/or Th2 cells. To identify DCs with differing abilities to direct Th1/Th2 cell differentiation, we cultured mouse bone marrow progenitors in granulocyte macrophage-colony stimulating factor (GM), GM + interleukin (IL)-4, or GM + IL-15 and generated three distinct DC populations. The GM + IL-4 DCs expressed high levels of CD80/CD86 and major histocompatibility complex (MHC) class II and produced low levels of IL-12p70. GM and GM + IL-15 DCs expressed low levels of CD80/CD86 and MHC class II. The GM + IL-15 DCs produced high levels of IL-12p70 and interferon (IFN)-gamma, whereas GM DCs produced only high levels of IL-12p70. Naive T cells stimulated with GM + IL-4 DCs secreted high levels of IL-4 and IL-5 in addition to IFN-gamma. In contrast, the GM + IL-15 DCs induced higher IFN-gamma production by T cells with little or no Th2 cytokines. GM DCs did not induce T cell polarization, despite producing large amounts of IL-12p70 following activation. A similar pattern of T cell activation was observed after in vivo administration of DCs. These data suggest that IL-12p70 production alone, although necessary for Th1 differentiation, is not sufficient to induce Th1 responses. These studies have implications for the use of DC-based vaccines in immunotherapy of cancer and other clinical conditions.

Y-box Protein-1 Is the Crucial Mediator of Antifibrotic Interferon-γ Effects

Y-box protein-1 (YB-1) is a known negative regulator of collagen (Col) expression by two different mechanisms, acting directly through binding to an interferon-gamma response element within the col1A2 promoter and/or by physically interacting with p300/Smad3, thereby abrogating the stimulatory effect of transforming growth factor-beta (TGF-beta). Here, we report that YB-1 activation via the Jak1 signaling pathway is required and sufficient to confer interferon-gamma-dependent activation of the smad7 gene. By binding to a bona fide recognition site within the smad7 promoter, YB-1 up-regulates smad7 transcription, which was additively enhanced by autoinhibitory TGF-beta signaling. Importantly, the anti-TGF-beta effect was not only supplied by induced Smad7 expression but was recapitulated in the context of the col1A2 promoter, where YB-1 overexpression abolished the trans-stimulatory TGF-beta effect in a dominant fashion. In conclusion, YB-1 is the main target of interferon-gamma signaling via Jak1 that exerts antifibrotic action by both interference with TGF-beta signaling and direct down-regulation of collagen expression.