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S F Wolf

Publications and source records attributed to S F Wolf.

At least 19 recordsLinked to original sources
PubMed1997

IL-12 induces IFN-gamma expression and secretion in mouse peritoneal macrophages.

We previously reported that resting mouse peritoneal macrophages (PM) constitutively express low levels of IFN-gamma, whose production is consistently enhanced by exogenous IFN-gamma. In this study, we investigated the effects of IL-12 on the replication of vesicular stomatitis virus and on IFN-gamma gene expression in mouse PM. The addition of IL-12 to freshly explanted PM resulted in the persistence of an antiviral state to vesicular stomatitis virus, while control PM progressively became permissive for virus replication after 3 to 4 days in culture. The IL-12-induced antiviral state was inhibited by Abs to IFN-gamma, suggesting that endogenous IFN-gamma was largely responsible for this antiviral response. Moreover, IL-12 induced a consistent secretion of IFN-gamma, especially in cultured PM. The IL-1 2-induced antiviral state and IFN-gamma production were observed using PM from various strains of mice, including LPS-defective C3H/HeJ, NK-deficient bg/bg, DBA/2, Swiss (CD1), and Swiss nude mice treated or not with anti-asialo GM1 Abs. A 4-h treatment with IL-12 was sufficient to induce a marked accumulation of IFN-gamma mRNA, which was greater in cultured PM than in freshly harvested cells. Lastly, immunofluorescence studies in IL-12-stimulated macrophages clearly showed an enhancement of immunoreactive IFN-gamma compared with basal levels in cells exhibiting a macrophage (i.e., F4/80-positive) phenotype. Together, these findings demonstrate that IL-12 can directly stimulate mouse PM to produce IFN-gamma. We suggest that IL-12-induced IFN-gamma production by macrophages can play some role in the generation of the antiviral and immunoregulatory effects of IL-12.

Animals↗
PubMed1996

Interleukin-12 stimulates B cell growth by inducing IFN-gamma.

Human interleukin-12 (IL-12) is a 70-kDa polypeptide that activates human natural killer cells. It has been purified from the culture supernatant of a human Epstein-Barr virus-transformed B cell line and cloned. We show that native as well as recombinant IL-12 promoted growth of Staphylococcus aureus Cowan I strain (SAC) or anti-mu antibody-activated B cells in a dose-dependent manner. IL-12 also acted in synergy with IL-2 in growth and differentiation of SAC-activated B cells. Since anti-interferon (IFN)-gamma antibody completely abrogates B-cell growth factor (BCGF) activity of IL-12, the BCGF activity is mediated by IFN-gamma. This conclusion is clearly supported by the results that IL-12 indeed induced IFN-gamma production by activated B cells. These results suggest that the B cell proliferative effect of IL-12 may be mediated by autocrine IFN-gamma.

Antigens, CD20↗
PubMed1996

IL-12, as an adjuvant, promotes a T helper 1 cell, but does not suppress a T helper 2 cell recall response.

IL-12 is a potent inducer of NK and cytolytic T cell activity, IFN-gamma production, and T cell proliferation, and is necessary for differentiation of naive T cells to the Th1 subset. We have previously shown that IL-12 promotes a primary Th1 response and suppresses a primary Th2 response in lymph nodes of mice primed with a model hapten-protein conjugate, 2,4,6-trinitrophenyl (TNP)-keyhole limpet hemocyanin (KLH). We have now extended these studies to determine the Th phenotype of the recall response following immunization with soluble Ag and IL-12. For these experiments, mice were primed with TNP-KLH with or without treatment with IL-12, allowed to progress beyond the primary immune response, and challenged by i.p. injection of TNP-KLH. The phenotype of the recall response was monitored by measuring ex vivo production of IFN-gamma and IL-4 in Ag-stimulated lymph node and spleen cell cultures. Titer and isotype of TNP-specific serum Abs were also evaluated. Mice primed with Ag+IL-12 developed a Th1 recall response, as detected by KLH-specific IFN-gamma production from cultured spleen cells and the presence of TNP-specific IgG2a Ab in serum. However, they also developed an Ag-specific Th2 recall response, as characterized by Ag-induced IL-4 production from spleen cells and the presence of high titers of anti-TNP IgG1 in the serum. Studies of the cytokine profile during the primary response revealed that IL-12 induced in spleen cells the capacity to express both IL-4 and IFN-gamma. CD4+ T cells are necessary for production of IL-4 in the spleens of IL-12-treated mice, and most likely account for the Th2 recall response detected in mice primed with Ag+IL-12. These results indicate that the Th1 phenotype induced by immunization with IL-12 and Ag is maintained so that a Th1 recall response is expressed upon subsequent challenge with Ag. However, immunization with IL-12 also supports the development of a Th2 recall response, indicating that the Th1-inducing effect of IL-12 in vivo is not accompanied by a long lasting suppression of Th2 development.

Adjuvants, Immunologic↗
PubMed1996

The interleukin 12 p40 gene promoter is primed by interferon gamma in monocytic cells.

Interleukin (IL) 12 is a proinflammatory cytokine produced by phagocytic cells, B cells, and other antigen-presenting cells that modulates adaptive immune responses by favoring the generation of T helper type 1 cells. IL-12 mediates some of its physiological activities by acting as a potent inducer of interferon (IFN) gamma production by T and natural killer cells. IFN-gamma enhances the ability of the phagocytic cells to produce IL-12 and other proinflammatory cytokines. Thus, IL-12-induced IFN-gamma acts in a positive feedback loop that represents an important amplifying mechanism in the inflammatory response to infections. We show here that IFN-gamma enhances IL-12 production mostly by priming phagocytic cells for lipopolysaccharide (LPS)-induced transcription of the IL-12 p40 gene, which encodes the heavy chain of the IL-12 heterodimer; furthermore, IFN-gamma directly induces transcription of the IL-12 p35 gene, which encodes the light chain of IL-12, and has at least an additive effect with LPS stimulation in inducing its transcription. The priming effect of IFN-gamma on the LPS-induced p40 gene transcription requires preincubation of the cells with IFN-gamma for at least 8 h to obtain a maximal effect. The priming effect of IFN-gamma for IL-12 production is predominantly at the transcriptional level for both the p40 and the p35 gene, and no evidence for a major role of posttranscriptional or translational mechanisms was found. A 3.3-kb human IL-12 p40 promoter construct transfected into cell lines recapitulated the tissue specificity of the endogenous gene, being silent in two human T cell lines, constitutively active in two human Epstein-Barr virus-positive B lymphoblastoid cell lines, and LPS inducible in the human THP-1 and mouse RAW264.7 monocytic cell lines. Because the RAW264.7 cell line is easily transfectable and regulates the endogenous IL-12 p40 gene in response to IFN-gamma or LPS similarly to human monocytes, it was used for analysis of the regulation of the cloned human IL-12 p40 promoter. A requirement for the region between -222 and -204 in both LPS responsiveness and IFN-gamma priming was established. This region contains an ets consensus sequence that was shown to mediate activation of the promoter by IFN-gamma and LPS, as well as by a cotransfected ets-2. The -222 construct was also regulated in a tissue-specific manner. Two other elements, IRF-1 located at -730 to -719, and NF-IL6 at -520 to -512, were also studied by deletion analysis, which did not result in decreased response to IFN-gamma and LPS stimulation.

Animals↗
PubMed1996

Interleukin (IL)-12 deficiency in susceptible mice infected with Mycobacterium avium and amelioration of established infection by IL-12 replacement therapy.

Mycobacterium avium is an intracellular microorganism that infects and multiplies within macrophages. Cell-mediated immunity plays an important role in host defense, and interleukin (IL)-12, which is produced mainly by macrophages, is critical for its development. In a mouse model of disseminated M. avium infection, genetically susceptible BALB/c mice had increased mycobacterial growth and decreased IL-12 expression and developed large and numerous granulomas. In contrast, resistant DBA/2 mice exhibited reduced mycobacterial burden with increased IL-12 expression and developed fewer and smaller granulomas. In susceptible mice with established M. avium infection, IL-12 replacement therapy resulted in persistent reduction of mycobacterial burdens. IL-12 itself, however, could not inhibit mycobacterial growth in vitro. By enhancing host defenses, IL-12 exerts a potent mycobactericidal activity in vivo with low toxicity. This suggests that IL-12 replacement therapy is rational for M. avium infection in susceptible hosts.

Animals↗
PubMed1996

Interleukin-12 production by human monocytes infected with Mycobacterium tuberculosis: role of phagocytosis.

Mycobacterium tuberculosis and its antigens are potent inducers of cytokine expression by mononuclear phagocytes. In this study, the ability of live M. tuberculosis to stimulate interleukin-12 (IL-12) expression by human monocytes was examined. Monocytes were purified from peripheral blood mononuclear cells by adherence and either infected with M. tuberculosis or exposed to soluble protein antigens of M. tuberculosis (purified protein derivative [PPD]). Live M. tuberculosis (10(6) to 10(7) CFU/ml) was a potent stimulus for interleukin-12 (IL-12). By using reverse transcription-PCR, p40 mRNA was detected at 3 h, peaked at 6 to 12 h, and decayed to baseline levels at 18 to 24 h following infection. Bioactive IL-12 (p70) was measured by the phytohemagglutinin blast proliferation assay and confirmed the p40 mRNA results. In contrast, soluble PPD at concentrations known to readily induce IL-1 and tumor necrosis factor alpha expression by monocytes (10 to 100 microg/ml) was a poor stimulus for IL-12 p40 mRNA expression. The different efficiencies of M. tuberculosis bacilli and PPD for IL-12 expression by monocytes was in part due to a requirement for phagocytosis. Induction of IL-12 in response to M. tuberculosis was reduced by cytochalasin D. Furthermore, phagocytosis of dead M. tuberculosis or inert 2-micron-diameter polystyrene beads by monocytes induced IL-12 p40 mRNA. In contrast, 0.5-micron-diameter beads, which can enter cells through pinocytosis, did not stimulate IL-12 expression. Functionally, IL-12 readily enhanced PPD-stimulated IFN-gamma production and CD4+ T-cell-mediated cytotoxicity by peripheral blood mononuclear cells from healthy tuberculin-positive donors but induced less enhancement when live M. tuberculosis was the antigen. These results suggest that IL-12 is upregulated as part of the early cytokine response of mononuclear phagocytes to M. tuberculosis and that the cellular events associated with phagocytosis are themselves a potent signal for IL-12 production. IL-12 released by infected macrophages in turn can further upregulate M. tuberculosis-specific CD4+ T-cell effector function.

Base Sequence↗
PubMed1995

IL-12-induced protection against blood-stage Plasmodium chabaudi AS requires IFN-gamma and TNF-alpha and occurs via a nitric oxide-dependent mechanism.

The effects of IL-12 administration on the development of protective immunity to blood-stage Plasmodium chabaudi AS were analyzed. Treatment of susceptible A/J mice on the day of infection and for 5 days postinfection with various doses 0.025-0.3 microgram) of rIL-12 significantly decreased the peak parasitemia level, but only treatment with 0.1 microgram resulted in increased survival. Treatment of resistant B6 mice with 0.1 microgram of rIL-12 using the same regimen also significantly decreased the peak parasitemia level, but 40% of the animals died. Treatment of these mice with anti-IL-12 mAb resulted in a more severe course of infection, but survival was not significantly altered. The mechanism of IL-12-induced resistance was examined in A/J mice during infection. Compared with spleen cells from untreated mice, cells from IL-12-treated mice produced significantly higher levels of IFN-gamma spontaneously as well as in response to Con A or Ag stimulation on day 7 postinfection. Significantly higher levels of INF-gamma and TNF-alpha were found in the sera of IL-12-treated mice, which correlated with high levels of the nitric oxide (NO) metabolite, NO3-. Furthermore, CD4+T cell depletion was found to abrogate IL-12-induced resistance. Administration of neutralizing mAb against IFN-gamma or TNF-alpha to IL-12-treated mice showed that simultaneous depletion of both cytokines resulted in 100% mortality. The role of NO was investigated by administration of aminoguanidine, a selective inhibitor of cytokine-inducible nitric oxide synthase, to IL-12-treated mice. Significantly increased mortality was observed following treatment twice daily with 9 mg of aminoguanidine, but there was no effect on parasitemia. In conclusion, these results demonstrate that IL-12 regulates the development of resistance to P. chabaudi AS via a CD4+ Th1 response, which involves the cytokines IFN-gamma and TNF-alpha, and is in part NO dependent. Therefore, IL-12, given in the appropriate dose, may be useful in the induction of protective immunity to blood-state malaria.

Animals↗
PubMed1995

Interleukin 12 suppresses autoantibody production by reversing helper T-cell phenotype in hepatitis B e antigen transgenic mice.

Helper T (Th) cells are classified as Th1 or Th2 cells by virtue of cytokine secretion and function as mediators of cellular or humoral immunity, respectively. Cytokines also regulate the differentiation of Th cells. For example, interleukin (IL)-12 promotes Th1 and suppresses Th2 cell development, suggesting that IL-12 may be useful therapeutically in Th2-mediated autoimmune and allergic disorders. Therefore, the effect of systemic IL-12 treatment on in vivo autoantibody synthesis in hepatitis B e antigen (HBeAg)-expressing transgenic mice, which is dependent on self-reactive Th2 cells, was examined. Low-dose IL-12 significantly inhibited autoantibody production by shifting the Th2-mediated response toward Th1 predominance. Additionally, previous studies suggest that a predominance of HBeAg-specific Th2-type cells may contribute to chronicity in hepatitis B virus infection. Therefore, IL-12 may also prove beneficial in modulating the HBeAg-specific Th response to favor viral clearance in chronic hepatitis B virus infection.

Animals↗
PubMed1995

IL-12 inhibits the production of IL-4 and IL-10 in allergen-specific human CD4+ T lymphocytes.

IL-12 influences cytokine synthesis in unprimed CD4+ T cells by enhancing IFN-gamma synthesis and enhancing the development of Th1 cells, but its effects upon Ag-primed T cells, which are thought to have relatively fixed cytokine profiles, is less clear. We investigated the capacity of IL-12 to modify cytokine synthesis in allergen-specific human CD4+ T lymphocytes from allergic donors after in vitro stimulation. CD4+ T cells were obtained from the peripheral blood of subjects with allergic rhinitis, depleted of activated T cells, and cultured with APCs and allergen. IL-12 dramatically inhibited the development of IL-4 and IL-10 synthesis, while it enhanced T cell secretion of IFN-gamma and IL-2, and enhanced Ag-specific T cell proliferation. The inhibitory effect of IL-12 on IL-4 synthesis was not dependent on the presence of IFN-gamma, was greatest when IL-12 was added at the initiation of culture, and was minimal when added late, indicating that resting memory CD4+ T cells were more sensitive than activated CD4+ T cells to the effects of IL-12. The effect of IL-12 on IL-4 and IL-10 synthesis was not dependent on the APC type, because IL-12 decreased IL-4 synthesis when either B cells or monocytes served as APCs. These results indicate that IL-12 may be therapeutically beneficial in the treatment of allergic diseases in which allergen-specific T cells characteristically produce enhanced quantities of IL-4 and IL-10.

Antigen-Presenting Cells↗
PubMed1995

IL-12 inhibits IL-4 synthesis in keyhole limpet hemocyanin-primed CD4+ T cells through an effect on antigen-presenting cells.

Although IL-12 is known to enhance IFN-gamma synthesis in unprimed CD4+ T cells, the effect of IL-12 on IL-4 synthesis in primed CD4+ T cells, which are thought to have relatively fixed cytokine profiles, has not been clearly examined. We examined the effects of IL-12 on cytokine production by CD4+ keyhole limpet hemocyanin (KLH)-primed memory lymph node T cells and by already established KLH-specific CD4+ T cell clones. First, we found that the presence of IL-12 greatly reduced the development of IL-4 synthesis in resting but not activated memory CD4+ T cells. Although IL-12 did not inhibit the production of IL-4 in cloned Th2 effector cells, it greatly inhibited the development of IL-4 synthesis in primed CD4+ T cells taken from the lymph nodes of mice previously immunized with KLH. Secondly, we found that IL-12 inhibited IL-4 synthesis either when directly added to cultures of T cells or when APC were preincubated in IL-12. Inasmuch as the enhancing effect of IL-12 on IFN-gamma synthesis occurred optimally only when the T cells were cultured directly in IL-12, these studies indicate that IL-12 affects IL-4 synthesis via a mechanism that involves APC, a process that differs from that by which it affects IFN-gamma synthesis. These studies also indicate that the administration of IL-12 would be clinically useful in treating patients, for example those with allergic disease or lepromatous leprosy, in whom memory T cells inappropriately overproduce IL-4.

Animals↗
PubMed1995

IL-12 reverses cytokine and immune abnormalities in Sezary syndrome.

Cutaneous T cell lymphoma is a lymphoproliferative disorder typically characterized by skin invasion of clonally derived malignant CD4+ lymphocytes that phenotypically resemble mature Th cells. Sezary syndrome (SzS) represents an advanced form of cutaneous T cell lymphoma associated with generalized erythroderma and involvement of the peripheral blood by the malignant cell population. We have previously demonstrated aberrant cytokine production by PBMC in SzS characterized by increased IL-4 and deficient IL-2 and IFN-gamma production, as well as increased expression of mRNA for IL-4 and IL-5 within active skin lesions, suggesting that the clonal T cell population is derived from the Th 2 subset of helper T lymphocytes. These findings have been associated with a constellation of immune abnormalities that have been attributed to the cytokine abnormalities. Because IL-12 is a potent inducer of IFN-gamma production, and causes the activation of cytotoxic lymphocytes, we examined the production of IL-12 by PBMC from SzS patients and whether IL-12 could alter the unfavorable cytokine balance typical of SzS and thus lead to correction of immune defects. Despite normal numbers of peripheral blood monocytes and normal TNF-alpha production, mean Staphyloccus aureus and LPS-induced IL-12 p40 and p70 production by SzS PBMC was significantly decreased compared with PBMC from normal controls. Mean IFN-gamma production by patient PBMC in response to PHA alone was depressed, but increased to levels comparable with normal after addition of 1 ng/ml IL-12. Pretreatment of PBMC for 24 h with IL-12, IFN-alpha, or both together resulted in a decrease in PHA-stimulated IL-4 production from a base line of 1818 pg/ml to 1520, 1350, and 1058 pg/ml, respectively. Lastly, culture of patient PBMC with IL-12 for 24 h also resulted in significant increases in NK activity against K562 cells. These results indicate that PBMC from patients with SzS manifest a defect in IL-12 production and that the cytokine abnormalities associated with SzS can be favorably altered by IL-12.

Cytokines↗
PubMed1995

Administration of systemic or local interleukin-2 enhances the anti-tumor effects of interleukin-12 gene therapy.

Interleukin-12 (IL-12) is a cytokine with a wide variety of immunoregulatory activities. These include stimulation of interferon-gamma production, cytolytic activity of natural killer (NK) cells and T-cell subsets, the development of cellular immunity, and induction of maturation of Th1 cells. IL-12 also has potent anti-tumor activity in vivo. In the present study the possibility of enhanced anti-tumor activity was examined using a combination of local IL-12 by cytokine gene therapy at the tumor site, combined with systemic or local IL-2 delivery. NIH 3T3 fibroblasts transfected with the genes for both subunits of IL-12, p35 and p40, were used as the source of IL-12 therapy producing 240 HLRU/10(6) cells/48 hr. In the first part of the study the effect of different regimens of systemic IL-2 delivery with local IL-12 administration on the size and growth rate of subcutaneous MCA-105 murine sarcoma was examined. Local IL-12 alone reduced the sizes of tumors after 32 days from 163 to 26.8 mm2 (P < 0.002). Adding the longer-acting polyethylene-glycol-modified IL-2 (PEG IL-2; 30,000 IU) for 5 days prevented the development of tumors in all treated mice compared to 1/3 mice treated with PEG IL-2 alone and 3/6 mice with IL-12, but this was a highly toxic therapy and most of the animals died. Administration of 60,000 IU of IL-2 on Days 1-5 postinoculation of tumor, delivered with IL-12 gene therapy, reduced the tumor growth rate compared to animals treated with IL-2 alone (P < 0.02) or IL-12 (0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1995

Systemic administration of rIL-12 induces complete tumor regression and protective immunity: response is correlated with a striking reversal of suppressed IFN-gamma production by anti-tumor T cells.

Unfractionated spleen cells taken from tumor-bearing mice 2 weeks after tumor implantation contained tumor-primed T cells which produced cytokines including IL-2 and IFN-gamma when cultured in vitro. With progressive tumor growth this initial lymphokine-producing capacity decreased. Here, we investigated the ability of IL-12 to (i) restore suppressed IFN-gamma production, (ii) cause tumor regression and (ii) induce anti-tumor protective immunity. Addition of rIL-12 to spleen cell cultures from 4- to 10-week-old tumor-bearing mice resulted in a striking enhancement in the production of IFN-gamma compared with cultures of these cells in the absence of rIL-12 or of normal spleen cells in the presence of rIL-12. Five i.p. injections of rIL-12 into mice bearing s.c. tumors induced complete tumor regression. This was found when rIL-12 was given at early (1-2 weeks), intermediate (4-5 weeks) or even late (7 weeks) stages of tumor growth. Furthermore, IL-12-treated mice which rejected the primary tumor exhibited complete resistance to a rechallenge with the same tumor but did not reject a second syngenetic tumor. Immunohistochemical analyses following IL-12 treatment revealed that CD4+ and CD8+ T cells infiltrate the tumor. More importantly, IFN-gamma mRNA expression was observed in fresh tumor masses from tumor-bearing mice receiving IL-12 treatment. The importance of IFN-gamma was further demonstrated by the observation that the systemic administration of anti-IFN-gamma mAb prior to IL-12 treatment completely abrogated the anti-tumor effect of IL-12. Thus, these results indicate that administration of modest levels of rIL-12 to tumor-bearing mice results in tumor regression through mechanisms involving reversal of suppressed IFN-gamma production by anti-tumor T cells and the establishment of a tumor-specific protective immune response.

Animals↗
PubMed1995

Interleukin-12 gene expression after viral infection in the mouse.

Interleukin-12 is a lymphokine that triggers gamma interferon secretion by various cells and differentiation of T-helper lymphocytes towards the Th1 subtype. Since viruses are potent inducers of gamma interferon production and elicit immune responses most probably mediated by Th1 cells, like B-cell immunoglobulin G2a secretion, we analyzed interleukin-12 message expression after infection of mice with lactate dehydrogenase-elevating virus, mouse hepatitis virus, and mouse adenovirus. Our results indicated that the message for the p40 component of interleukin-12 was transiently increased shortly after infection. Interleukin-12 was expressed mainly by macrophages. Therefore, production of interleukin-12 might constitute the initial event that would determine the subsequent characteristics of the immune response elicited by viral infections.

Adenoviridae Infections↗
PubMed1994

Type 1/type 2 cytokine modulation of T-cell programmed cell death as a model for human immunodeficiency virus pathogenesis.

In vitro T-cell receptor-induced programmed cell death in both activated T cells from human immunodeficiency virus-seronegative (HIV-) donors and resting T cells from HIV+ donors was substantially influenced by cytokines. Addition of exogenous recombinant "type 1" lymphokines interferon gamma and interleukin 2 (IL-2), as well as the macrophage-produced IL-12, which favor cell-mediated T-cell responses, blocks both systems of T-lymphocyte programmed cell death. In contrast, the "type 2" lymphokines IL-4 and IL-10, which favor antibody responses, either had no effect or enhanced these systems of in vitro T-cell programmed cell death. A role for endogenously produced cytokines was suggested by the inhibition of T-cell receptor-mediated death by antibodies against IL-4 and IL-10 and its enhancement by anti-IL-12 in cultures containing monocytes. These results demonstrate that the functional properties of type 1 and type 2 cytokine classes may be further extended to include their effects on T-cell programmed cell death and their possible role in the pathogenesis of HIV infection.

Apoptosis↗