Biological and antigenic similarities of murine interferon-gamma and macrophage-activating factor

Intraperitoneal activation of myeloid cells clears ascites and reveals IL27-dependent regression of metastatic ovarian cancer

Patients with metastatic ovarian cancer (OvCa) have a 5-year survival rate of less than 30% due to persisting dissemination of chemoresistant cells in the peritoneal fluid and the immunosuppressive microenvironment in the peritoneal cavity. Here, we report that intraperitoneal administration of β-glucan and IFNγ (BI) induced robust tumor regression in clinically relevant models of metastatic OvCa. BI induced tumor regression by controlling fluid tumor burden and activating localized antitumor immunity. β-glucan alone cleared ascites and eliminated fluid tumor cells by inducing intraperitoneal clotting in the fluid and Dectin-1-Syk-dependent NETosis in the omentum. In omentum tumors, BI expanded a novel subset of immunostimulatory IL27+ macrophages and neutralizing IL27 impaired BI efficacy in vivo. Moreover, BI directly induced IL27 secretion in macrophages where single agent treatment did not. Finally, BI extended mouse survival in a chemoresistant model and significantly improved chemotherapy response in a chemo-sensitive model. In summary, we propose a new therapeutic strategy for the treatment of metastatic OvCa.

Inhibition of Tumor Growth and Metastasis by Newcastle Disease Virus Strain P05 in a Breast Cancer Mouse Model

PURPOSE

Conventional therapies and surgery remain the standard treatment for breast cancer. However, combating the eventual development of metastasis is still a challenge. Newcastle disease virus (NDV) is one of the various species of viruses under clinical evaluation as a vector for oncolytic, gene-, and immune-stimulating therapies. The purpose of this study was to evaluate the antitumor activity of a recombinant NDV (rNDV-P05) in a breast cancer murine model.

METHODS

Tumors were induced by injecting the cellular suspension (4T1 cell line) subcutaneously. The virus strain P05 was applied three times at intervals of seven days, starting seven days after tumor induction, and was completed 21 days later. Determination of tumor weight, spleen index, and lung metastasis were done after sacrificing the mice. Serum levels of interferon (IFN)-α, IFN-γ, tumor necrosis factor (TNF)-α, and TNF-related apoptosis-inducing ligand (TRAIL) were quantified by enzyme-linked immunosorbent assay. CD8+ infiltrated cells were analyzed by immunofluorescence.

RESULTS

rNDV-P05 showed a route-of-administration-dependent effect, demonstrating that the systemic administration of the virus significantly reduces the tumor mass and volume, spleen index, and abundance of metastatic clonogenic colonies in lung tissue, and increases the inhibition rate of the tumor. The intratumoral administration of rNDV-P05 was ineffective for all the parameters evaluated. Antitumor and antimetastatic capability of rNDV-P05 is mediated, at least partially, through its immune-stimulatory effect on the upregulation of TNF-α, TRAIL, IFN-α, and IFN-γ, and its ability to recruit CD8+ T cells into tumor tissue.

CONCLUSION

Systemic treatment with rNDV-P05 decreases the tumoral parameters in the breast cancer murine model.

Effect of Chlorovirus ATCV-1 infection on behavior of C57Bl/6 mice

Neuroinflammation induced during immune responses to viral infections in the brain affect behavior. Unexpected evidence that oral gavage of an algal virus in its host algal cells could alter cognition was further examined by directly injecting purified algal virus ATCV-1 intracranially into C57BL/6 mice. After 4weeks, the ATCV-1 infection impaired delayed location recognition memory, and also reduced and anxiety. Corresponding to these effects, heightened ATCV-1, IL-6, iNOS, IFN-γ, and CD11b expression in brains was observed 3-days and/or 8-weeks post infection compared with control mice. These results imply that ATCV-1 infection damages the hippocampus via induction of inflammatory factors.

Evaluation of immunological status in tumor-bearing dogs

The purpose of this study was to evaluate immunological status in dogs with cancers at different stages, in comparison with normal dogs. The population of canine peripheral blood lymphocytes (cPBL), lymphocyte phenotypes, interleukin (IL)-6 activity and alpha 1-acid glycoprotein (alpha(1)-AG) level were analyzed. The tumor-bearing dogs had higher numbers of leukocytes than normal dogs, the count being higher in dogs with more advanced tumors. In the tumor-bearing dogs, differential leukocyte counts revealed higher percentages of inflammatory cells such as neutrophils, acidophils and monocytes, and lower numbers of CD4(+)T cells, than in normal dogs, the lymphocyte counts becoming much lower with tumor progression. In the tumor-bearing dogs, the CD8(+)T cell count at the early tumor stage was similar to that in normal dogs, but decreased with tumor progression, possibly reflecting the development of humoral immunity (Th2). Plasma IL-6 and TGF-beta activities were high in the tumor-bearing dogs. The plasma alpha(1)-AG concentration was also significantly high in the tumor-bearing dogs. Our findings suggest that assay of IL-6, TGF-beta and alpha(1)-AG may be very useful for prognostication in dogs with cancer, and that anti-tumor immunity is potently suppressed in such dogs.

Limited role of macrophages in generation of nerve injury-induced mechanical allodynia

The purpose of this study was to investigate the role of peripheral macrophages in the generation of mechanical allodynia utilizing a modification of the Chung rat model of neuropathy. Three distinct methods were used: (1) systemic and perineural macrophage inhibition utilizing CNI-1493; (2) depletion of the peripheral macrophage population by liposome-encapsulated clodronate; and (3) perineural administration of activated or inactivated bone marrow-derived macrophages (BMDM) in sham-surgery rats. Mechanical allodynia was tested on days 1, 3, 5, 7, and 10 post-intervention or surgery using von Frey monofilaments. In order to assess the role of spinal glia following these interventions, microglial (CNS macrophages) and astrocytic activation was assessed using immunohistochemistry. CNI-1493 did not attenuate mechanical allodynia, or spinal glial expression as compared to the saline control group. Similarly, the clodronate depletion of peripheral macrophages prior to nerve injury did not have any effect on the resultant mechanical allodynia or spinal glial activation. Perineural administration of activated or inactivated BMDM did not evoke mechanical allodynia in sham surgery rats. Of interest, we observed an ipsilateral, dorsal horn increase in microglial expression following perineural administration of activated macrophages. In summary, these data suggest a limited role of activated macrophages in the onset of mechanical allodynia in an animal model of neuropathy.

Mediators of ischemia-reperfusion injury of rat lung

In rats, we characterized the mediators of lung reperfusion injury after ischemia. Animals underwent left lung ischemia. After 90 minutes of ischemia, reperfusion for up to 4 hours was evaluated. Lung injury, as determined by vascular leakage of serum albumin, increased in ischemic-reperfused animals when compared with time-matched sham controls. Injury was biphasic, peaking at 30 minutes and 4 hours of reperfusion. The late but not the early phase of reperfusion injury is known to be neutrophil dependent. Bronchoalveolar lavage of ischemic-reperfused lungs at 30 minutes and 4 hours of reperfusion demonstrated increased presence of serum albumin, indicative of damage to the normal vascular/airway barrier. Lung mRNA for rat monocyte chemoattractant protein-1 and tumor necrosis factor-alpha peaked very early (between 0.5 and 1.0 hour) during the reperfusion process. Development of injury was associated with a decline in serum complement activity and progressive intrapulmonary sequestration of neutrophils. Administration of superoxide dismutase before reperfusion resulted in reduction of injury at 30 minutes of reperfusion. Complement depletion decreased injury at both 30 minutes and 4 hours of reperfusion. Requirements for tumor necrosis factor-alpha, interferon-gamma, and monocyte chemoattractant protein-1 for early injury were shown whereas only tumor necrosis factor-alpha was involved at 4 hours. We propose that acute (30-minute) lung injury is determined in large part by products of activated lung macrophages whereas the delayed (4-hour) injury is mediated by products of activated and recruited neutrophils.

Identification of a lipopolysaccharide inducible transcription factor in murine macrophages

To study macrophage genes activated by lipopolysaccharide (LPS) we have constructed a cDNA library using the mouse macrophage cell line, RAW 264.7. By differential screening, a gene, designated LRG-21, was identified that showed nucleic acid sequence homology to rat liver regenerating factor-1 (LRF-1) and human activating transcription factor-3 (ATF3). Both LRG-21 and LRF-1 are transcribed within an hour following stimulation and in the absence of protein synthesis. The predicted protein sequence of LRG-21 consists of 181 amino acids with a molecular weight of 20.7 kDa. All three sequences contain basic and leucine zipper regions characteristic of the c-Fos and c-Jun family of transcription factors, but the remainder of the sequences are unrelated to this family. Recombinant LRG-21 has been shown to bind to a phorbol ester promoter element. Additional experiments have shown that LRG-21 is also induced by interferon-gamma (IFN-gamma) and by interleukin-4 (IL-4) in both RAW264.7 cells and murine peritoneal macrophages. Based on these observations, it is likely that LRG-21 plays an important role in macrophage activation.

Role of nitric oxide in parasitic infections

Nitric oxide is produced by a number of different cell types in response to cytokine stimulation and thus has been found to play a role in immunologically mediated protection against a growing list of protozoan and helminth parasites in vitro and in animal models. The biochemical basis of its effects on the parasite targets appears to involve primarily inactivation of enzymes crucial to energy metabolism and growth, although it has other biologic activities as well. NO is produced not only by macrophages and macrophage-like cells commonly associated with the effector arm of cell-mediated immune reactivity but also by cells commonly considered to lie outside the immunologic network, such as hepatocytes and endothelial cells, which are intimately involved in the life cycle of a number of parasites. NO production is stimulated by gamma interferon in combination with tumor necrosis factor alpha or other secondary activation signals and is regulated by a number of cytokines (especially interleukin-4, interleukin-10, and transforming growth factor beta) and other mediators, as well as through its own inherent inhibitory activity. The potential for design of prevention and/or intervention approaches against parasitic infection (e.g., vaccination or combination chemo- and immunotherapy strategies) on the basis of induction of cell-mediated immunity and NO production appears to be great, but the possible pathogenic consequences of overproduction of NO must be taken into account. Moreover, more research on the role and regulation of NO in human parasitic infection is needed before its possible clinical relevance can be determined.

Cytokines and murine autoimmune encephalomyelitis: inhibition or enhancement of disease with antibodies to select cytokines, or by delivery of exogenous cytokines using a recombinant vaccinia virus system

To examine the complex role of cytokines in the pathogenesis of actively induced murine EAE we measured the levels of a number of cytokines (IL-6, IFN gamma and TNF) in the spinal cord and CSF of mice with active experimental autoimmune encephalomyelitis (EAE) and found them all to be elevated. We next treated mice with antibodies to these three cytokines, which were over expressed in the CNS, to determine if they would alter disease and found the following: anti-IL-6 had no significant effect on disease, anti-IFN gamma exacerbated disease, and anti-TNF either enhanced, had no effect or inhibited EAE depending on the antibody used. We then treated mice with exogenous cytokines, delivered using a recombinant vaccinia virus system, and found that the IL-6 and TNF virus constructs inhibited EAE whereas the IFN gamma construct had no effect on disease. Other cytokine recombinant viruses were also tested and it was found that the IL-1 beta, IL-2 and IL-10 viruses inhibited EAE while an IL-4 virus either had no effect or enhanced disease. We do not know the mechanism of action of the various cytokines in this system, but irrespective of the mechanism(s), this work clearly demonstrates that delivery of select cytokines using recombinant virus-cytokine constructs can provide a powerful means of down-regulating experimental organ-specific autoimmune disease.

MDP-Lys(L18), a lipophilic derivative of muramyl dipeptide, inhibits the metastasis of haematogenous and non-haematogenous tumours in mice

The antimetastatic effects of MDP-Lys(L18), a lipophilic derivative of muramyl dipeptide (MDP), against three different types of highly metastatic murine tumour cells, B16-BL6 melanoma, colon 26-M3.1 carcinoma and L5178Y-ML25 T lymphoma, were examined in C57BL/6, Balb/c and CDF1 mice, respectively. The administration of 100 micrograms of MDP-Lys(L18) 2 or 4 days before tumour inoculation led to a significant decrease in lung metastasis of B16-BL6 melanoma or colon 26-M3.1 carcinoma cells. MDP-Lys(L18) was also effective in the inhibition of liver metastasis of L5178Y-ML25 lymphoma cells by administration 2 or 4 days before tumour inoculation. The prophylactic effect of 100 micrograms of MDP-Lys(L18) on tumour metastasis was evident for the different administration routes, i.e. subcutaneous, intravenous or intranasal injection, or oral administration. It is of prime interest that oral administration of 1 mg of MDP-Lys(L18) induced a significant decrease in lung metastasis of B16-BL6 melanoma cells. Administration of MDP-Lys(L18) 4 days before assay led to induction of tumoricidal activity by peritoneal macrophages and growth inhibition by the sera against B16-BL6 or L929 cells. When MDP-Lys(L18) was subcutaneously administered five times after tumour inoculation to test therapeutic effect in an experimental and spontaneous metastasis model using B16-BL6 melanoma, the consecutive administrations of MDP-Lys(L18) significantly inhibited lung metastasis in tumour-bearing mice. These results suggest that MDP-Lys(L18) is able to enhance host resistance to reduce tumour metastasis and is a potent immunomodulating agent which may be applied prophylactically or therapeutically for the treatment of cancer metastasis.

Interferon-gamma and interleukin-4 reciprocally regulate the production of monocytes/macrophages and neutrophils through a direct effect on committed monopotential bone marrow progenitor cells

We studied the direct effects of interferon-gamma (IFN-gamma) in single cell colony assays of CD34+HLA-DR++ bone marrow progenitor cells stimulated by either granulocyte-colony-stimulating factor (G-CSF), interleukin(IL)-3, granulocyte/macrophage-colony-stimulating factor (GM-CSF), combinations of these CSF or medium conditioned by the 5637 human bladder carcinoma cell line. In this culture system IFN-gamma stimulated monocytic colonies (CFU-M) no matter which CSF or CSF combination was used to support them and inhibited granulocytic colonies (CFU-G) if they were generated in the presence of G-CSF. IL-4 antagonized the myelopoietic effects of IFN-gamma: the IFN-gamma-induced suppression of G-CSF-supported CFU-G, as well as the stimulation of CFU-M, were reversed by IL-4. In all cultures, IFN-gamma had a limited, but statistically non-significant, inhibitory effect on CFU-GM, which was not affected by the presence of IL-4. These data show that IFN-gamma and IL-4 reciprocally regulate the generation of myeloid cells involved in humoral (neutrophils) and cellular (macrophages) immune responses through a direct effect on monopotential myeloid progenitor cells.

Regulation of interleukin-2 and interferon-gamma gene expression in renal failure

Regulated expression of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) genes, induced in cultured peripheral blood mononuclear cells from patients with end-stage renal disease on hemodialysis (HD; N = 13) or peritoneal dialysis (PD; N = 13), was compared to that of 32 normal donors. Culture conditions were chosen that measure the transient, phytohemagglutinin-induced expression of IL-2 and IFN-gamma messenger RNA (mRNA), as well the intactness of post-transcriptional and suppressor T cell-dependent mechanisms that control this expression. The latter was achieved by analyzing the superinduction of IL-2 and IFN-gamma mRNA occurring upon culture with cycloheximide or after low-dose gamma-irradiation, respectively. HD subjects showed a complete loss of inducibility of the IL-2 gene, concomitant with decreased inducibility of IFN-gamma mRNA. In PD subjects, by contrast, expression of IL-2 mRNA was as vigorous as in normal donors, while IFN-gamma mRNA was even more strongly inducible. This difference in gene inducibility is caused by a lack of T cell function in HD subjects. The defect in IL-2 gene expression in HD subjects, occurring most likely at transcription, may underly their impaired immune function.

Nonspecific defence mechanism: the role of nitric oxide

There is a marked contrast between the extraordinary complexity and specificity of the adaptive immune response and the limited number of effector mechanisms that it can direct. Recently, a great deal of interest has focused on the possible role of nitric oxide (NO) in one of these mechanisms. Here F.Y. Liew and Frank Cox examine the evidence supporting a role for NO in parasitic disease and suggest possible mechanism of NO-mediated parasite damage.

Augmented production of granulocyte-macrophage colony-stimulating factor and alpha/beta interferon in mice inoculated with heat-killed Corynebacterium liquefaciens

We demonstrated that heat-killed Corynebacterium liquefaciens bacteria, as a known potent host immune activity modulator, stimulate spleen cells to produce granulocyte-macrophage (GM) colony-stimulating factor (CSF) and another CSF with similar activity, as well as alpha/beta interferon, when injected intravenously into mice. Alpha/beta interferon was shown to be produced by C. liquefaciens-activated plastic-G-10 column-adherent cells (A cells) in a thymus-independent manner. In contrast, augmented production of GM-CSF required the action of C. liquefaciens-activated T lymphocytes that collaborated with normal A cells. Non-T spleen cells from C. liquefaciens-stimulated athymic mice, however, produced an alternative CSF that partially replaced GM-CSF. Correspondingly, the numbers of GM-producing CFU developing in cultures of spleen cells from C. liquefaciens-treated euthymic or athymic mice were 10 to 30 times higher than those in cultures of spleen cells from untreated mice. These results suggest that gram-positive rods such as C. liquefaciens activate T and A cells for production of multiple cytokines and that potential cooperative actions of these cytokines underlie the known immunomodulatory action of coryneforms.

Aberrant regulation of interleukin-2 but not of interferon-gamma gene expression in Down syndrome (trisomy 21)

The regulated expression of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) genes was analyzed in peripheral blood mononuclear cells derived from 29 noninstitutionalized Down syndrome individuals and compared to that of 32 normal donors. Culture conditions were chosen that measure the transient, phytohemagglutinin-induced expression of IL-2 and IFN-gamma mRNA, as well as the intactness of post-transcriptional and suppressor T cell-dependent mechanisms that control this expression. The latter was achieved by analyzing, respectively, the superinduction of IL-2 and IFN-gamma mRNA occurring upon culture with cycloheximide or after low-dose gamma-irradiation. A convenient, sensitive, and quantitative assay for specific mRNA was devised, suitable for measuring mRNA levels expressed in cells from 1 ml of peripheral blood. Analysis of individuals with Down syndrome revealed a pronounced decrease in inducibility of the IL-2 gene. By contrast, induction of IFN-gamma mRNA was as vigorous as that observed for normal donors. In cells from trisomic subjects, superinduction of IFN-gamma mRNA by cycloheximide was at least as extensive as for normal donors, while in the case of IL-2 mRNA, it was weaker. These abnormal patterns of IL-2 gene expression were seen irrespective of age. Our findings demonstrate a selective impairment of IL-2 gene expression in Down syndrome, rather than a general deficiency in helper T cells.

Kinetics and requirements for activation of macrophages for fungicidal activity: effect of protein synthesis inhibitors and immunosuppressants on activation and fungicidal mechanism

Peritoneal-and pulmonary macrophages can be activated in vitro with lymphokines (LK) or IFN-gamma, without exogenous lipopolysaccharide, for fungicidal activity against several pathogenic fungi. However, neither the biochemical nor metabolic events of the activation process or of the effector phase have been defined. In the present work we sought to elucidate these events with time-course studies using inhibitors of protein synthesis as well as immunosuppressive agents. We found that protein synthesis inhibitors abrogated the activation process, because cycloheximide (CHX) (1-2 micrograms/ml) prevented activation of macrophages for fungicidal activity against Candida albicans, Blastomyces dermatitidis, and Paracoccidioides brasiliensis. Blocking of the activation process by CHX was not due to macrophage cytotoxicity, and CHX did not impair the ability of nonactivated macrophages to kill Candida parapsilosis. In kinetic studies we showed that activation of macrophages was induced in 4 hr of LK treatment and that CHX had no effect if added after this time. In contrast to CHX, therapeutic concentrations of hydrocortisone (HC), such as less than or equal to 5 micrograms/ml, or cyclosporin A (CsA), 5 micrograms/ml, did not significantly inhibit LK activation of macrophages for killing of fungi. In the effector phase, the fungicidal capacity of activated macrophages in short-term (less than or equal to 4 hr) killing assays could not be abrogated by CHX (5 micrograms/ml), HC (100 micrograms/ml), or CsA (10 micrograms/ml). These results demonstrate that the activation but not the effector mechanism of macrophages for fungicidal activity is blocked by inhibition of protein synthesis. In contrast, therapeutic concentrations of HC or CsA may not interfere with activation of macrophages or their killing mechanisms, thus providing a rationale for antifungal immunotherapy in certain clinical situations (e.g., infection in the immunosuppressed patient).

Pulmonary disease in AIDS patients

Pulmonary disease remains a major complication of the human immunodeficiency virus (HIV). Over the past decade several changes in the pattern of disease have occurred. Pneumocystis carinii pneumonia (PCP) remains the most common opportunistic pathogen in AIDS patients, though its incidence on bronchoscopy has declined and empiric therapy often occurs without a specific diagnosis. Changes in the management of patients with PCP have included different dosages and routes of administration for chemotherapy, improved overall survival, and a recent increase in the number of patients surviving episodes of respiratory failure. In addition, infection with mycobacteria tuberculosis (M.Tb.) has emerged as a major public health problem. The pattern of M.Tb. is distinct from non-immunocompromised patients though response to therapy usually occurs.

Effect of gamma-interferon on phagosome-lysosome fusion in Salmonella typhimurium-infected murine macrophages

Effect of recombinant gamma-interferon (rIFN-gamma) on phagosome-lysosome fusion in Salmonella typhimurium-infected murine macrophages was examined. rIFN-gamma enhanced phagosome-lysosome fusion in macrophages infected with S. typhimurium in a dose-dependent manner, and over a range of 10(2) to 10(3) U/ml of rIFN-gamma exhibited maximum phagosome-lysosome fusion, although phagocytosis was slightly decreased. The enhancement of phagosome-lysosome fusion occurred greater than 3 h post-treatment with rIFN-gamma. Furthermore, the macrophage activation for phagosome-lysosome fusion was found to persist for 4 days even when rIFN-gamma had been removed. These results demonstrate that IFN-gamma may serve as a mediator for the activation of phagosome-lysosome fusion in murine macrophages.

Suppression of experimental allergic encephalomyelitis by intraventricular administration of interferon-gamma in Lewis rats

Experimental allergic encephalomyelitis (EAE) is an autoimmune inflammatory disease of the central nervous system (CNS) which causes paralysis. Several studies have reported the involvement of Ia antigen-expressing cells in the pathogenesis of EAE. Interferon-gamma (IFN-gamma) can induce Ia antigen expression on a wide range of cells. We examined the effect of IFN-gamma on EAE in Lewis rats. Systemically administered IFN-gamma did not change the disease course of EAE, whereas IFN-gamma applied locally into the ventricular system of the CNS resulted in complete suppression of clinical signs. Furthermore, we found that systemic administration of anti-IFN-gamma just prior to the onset of clinical symptoms resulted in a more severe disease course. We conclude that IFN-gamma is capable of exerting a suppressive action in EAE, possibly through induction of Ia antigen expression or through the induction of suppressive mechanisms locally in the CNS.

Activation by synthetic lipid A subunit analogues (GLA compounds) of tumoricidal properties in human blood monocytes

The authors have determined that synthetic lipid A subunit analogues (GLA compounds), as well as E. coli type lipopolysaccharide (LPS) and synthetic lipid A (compound 506), are able to stimulate human monocytes to become cytotoxic against tumour target cells in vitro. GLA-60, a synthetic lipid A subunit analogue of low toxicity, was found to be more active for the induction of tumoricidal monocytes than GLA-59, and similar to that of LPS. GLA-60 could induce not only the secretion of cytotoxic factor into the culture supernatant but also expression of the membrane-associated form of cytotoxic factor in human monocytes. Supernatant-mediated cytotoxicity was completely inhibited by the addition of monoclonal anti-human TNF antibody. These results indicate that a synthetic lipid A subunit analogue, GLA-60, would be a useful activator of tumoricidal monocytes in spite of its low toxicity.

The role of interferon-gamma in the pathogenesis of experimental autoimmune disease of the peripheral nervous system

The role of interferon-gamma in the pathogenesis of experimental autoimmune disease of the peripheral nervous system was investigated. Administration of rat recombinant interferon-gamma markedly augmented both myelin-induced and T-cell line-mediated experimental autoimmune neuritis. Conversely, in vivo application of a monoclonal antibody to interferon-gamma suppressed the disease. Clinical and electrophysiological findings were corroborated by semiquantitative morphometric analysis. Mechanisms responsible for the enhancing effects of interferon-gamma include upregulation of major histocompatibility complex class II antigen expression in the nerve lesion, increased cellular influx of T cells and macrophages, and heightened macrophage activity with enhanced release of toxic oxygen species. These observations establish a pivotal role of the cytokine interferon-gamma in the pathogenesis of experimental autoimmune disease of the peripheral nervous system.

Production of interleukin 1 from human monocytes stimulated by synthetic lipid A subunit analogues

We have investigated that synthetic lipid A subunit analogues (GLA compounds) as well as E. coli type lipopolysaccharide (LPS) and synthetic lipid A (compound 506) are able to stimulate human monocytes to release IL-1 in vitro. Of monosaccharide-type GLA compounds, GLA-60 was found to be more active for the induction of IL-1 production than GLA-59 and GLA-27, and similar to that of LPS or compound 506. GLA-60 could induce not only the secretion of IL-1 into culture supernatant but also the expression of membrane-associated form of IL-1 in human monocytes. Furthermore, no detectable IL-2 activity was observed in the culture supernatant. These results show that synthetic lipid A analogues of low toxicity, in particular GLA-60, are active in inducing IL-1 production in human monocytes.

Cure of murine leishmaniasis with anti-interleukin 4 monoclonal antibody. Evidence for a T cell-dependent, interferon gamma-independent mechanism

BALB/c mice infected with Leishmania major develop fatal, progressive disease, despite an immune response characterized by expansion of CD4+ T cells in the draining lymph nodes. The immune response has been further characterized by a lack of IFN-gamma mRNA, but increased IL-4 mRNA in lymphoid tissues, and striking elevation of serum IgE. Treatment of infected BALB/c mice with rIFN-gamma at doses shown to be beneficial in other protozoan infections was insufficient to ameliorate L. major infection. In contrast, neutralization of IL-4 by six weekly injections of mAb 11B11 led to attenuation of disease in 100% of animals, and complete cure in 85%. Resolution of disease required the presence of T cells, and recovered mice remained resistant to reinfection at 12 wk. This immunity was adoptively transferable and was dependent on both CD4+ and CD8+ cells. Although administration of anti-IL-4 was associated with fourfold increase in IFN-gamma mRNA in lymph node cells draining the lesion, the coadministration of neutralizing R4 6A2 anti-IFN-gamma mAb had no effect on resistance to disease. This was in marked contrast to resolution of disease in both resistant C57BL/6- and GK1.5-pretreated BALB/c mice that was abrogated by in vivo treatment with anti-IFN-gamma. These data suggest a novel mechanism of cellular immunity established by interference with the development of Th2 cells during infection.

Lung defenses against opportunistic infections

This review has examined the possible role of CMI in providing protection against three pathogens that can be opportunists in the lung. Monoclonal antibodies that identify the cellular components of the immune response and recombinant cytokines are important tools to better understand how pulmonary immunity is regulated. Although not discussed in detail, recombinant microbial antigens are useful for understanding various aspects of protective immunity and immunosuppression as well as for advancing vaccine development. There are important problems to address in order to continue steady progress in understanding pulmonary defenses, including some of those mentioned in this brief review. There should be an increased use of infectious models that more closely mimic naturally occurring infections, and comparisons should be made between results obtained with parenteral versus intrapulmonary routes of infection.

Gamma-interferon-induced monocyte major histocompatibility complex class II antigen expression individuals with acquired immune deficiency syndrome

Twelve patients with the acquired immune deficiency syndrome (AIDS) and Kaposi's sarcoma were treated with recombinant human gamma-interferon (rIFN-gamma). A rapid, substantial increase in the fraction of HLA-DQ-positive monocytes was noted after treatment with rIFN-gamma. The rIFN-gamma-induced increase in monocyte HLA-DQ was seen throughout the course of treatment, with the percentage of HLA-DQ-positive monocytes dropping slightly following each week's treatment with rIFN-gamma and then rapidly increasing following the next course of treatment. Although the percentage of HLA-DR-positive monocytes was unchanged (HLA-DR was expressed on greater than 80% of monocytes prior to treatment), the density of HLA-DR on monocytes also increased following rIFN-gamma treatment. Following rIFN-gamma treatment, no changes were seen in CD3, CD4, CD8 T cell numbers, in T cell subset ratio (CD4/CD8), in Leu 7 or CD16 (Leu 11) cell number, in spontaneous Ig secretion, in PHA-induced in vitro proliferation, or in NK activity. These results indicate that exposure to rIFN-gamma in vivo led to the increased expression of class II antigens on monocytes in patients with AIDS.

In vivo activation of peripheral blood polymorphonuclear neutrophils by gamma interferon results in enhanced fungal killing

The effect of in vivo administration of murine recombinant gamma interferon (IFN) on the fungicidal activity of murine peripheral blood polymorphonuclear neutrophils (PB-PMNs) was studied. Mice were injected intramuscularly with 250, 2,500, 25,000 or 250,000 U of IFN 5 h before collection of peripheral blood. Purified PB-PMNs were cocultured in vitro with Blastomyces dermatitidis yeast cells for 2 h. PB-PMNs from untreated mice killed 44.5 +/- 12.5% of the fungal inoculum, whereas PB-PMNs from mice treated with 25,000 or 250,000 U of IFN showed significantly enhanced in vitro killing (68.0 +/- 9.4% [P less than 0.005] and 72.3 +/- 1.1% [P less than 0.001], respectively). Treatment with 250 or 2,500 U of IFN or 25,000 U of heated (100 degrees C, 15 min) IFN had no effect. The IFN-induced activation of PB-PMNs was transitory. Significant enhancement of PB-PMN killing activity occurred 1, 2, or 5 h after in vivo IFN administration, but no enhancement was observed 16 or 24 h after IFN treatment. Enhanced fungicidal activity by PB-PMNs from mice treated for 5 h with 25,000 U of IFN correlated with an increased release of superoxide anion (O2-) in vitro after stimulation of PB-PMNs with phorbol ester; normal PB-PMNs and IFN-activated PB-PMNs, respectively, produced 2.2 +/- 2.5 and 23.5 +/- 4.8 nmol of O2- per 10(6) PB-PMNs per 30 min (P less than 0.005). The exogenous addition of compounds that antagonize or inhibit the formation of oxygen radicals (superoxide dismutase, catalase, dimethyl sulfoxide, or sodium azide) significantly inhibited fungal killing by both normal and IFN-activated PB-PMNs. In addition to the enhanced microbicidal activity and superoxide generation demonstrated in vitro with constant cell numbers, there was a transient leukocytosis (particularly neutrophilia) in peripheral blood at doses of IFN and at times after IFN administration where enhanced activity was also demonstrated. In summary, our results indicate that PB-PMNs can be activated in vivo for enhanced killing of a fungal target. The enhanced killing capacity of IFN-activated PB-PMNs is due at least in part to the enhancement of oxidative killing mechanisms.

Intracellular multiplication of Paracoccidioides brasiliensis in macrophages: killing and restriction of multiplication by activated macrophages

The effect of coculturing yeast-form Paracoccidioides brasiliensis with murine cells was studied. Coculture of resident peritoneal or pulmonary macrophages with P. brasiliensis for 72 h dramatically enhanced fungal multiplication 19.3 +/- 2.4- and 4.7 +/- 0.8-fold, respectively, compared with cocultures with lymph node cells or complete tissue culture medium alone. Support of P. brasiliensis multiplication by resident peritoneal macrophages was macrophage dose dependent. Lysates of macrophages, supernatants from macrophage cultures, or McVeigh-Morton broth, like complete tissue culture medium, did not support multiplication of P. brasiliensis in 72-h cultures. Time course microscopic studies of cocultures in slide wells showed that macrophages ingested P. brasiliensis cells and that the ingested cells multiplied intracellularly. In sharp contrast to resident macrophages, lymphokine-activated peritoneal and pulmonary macrophages not only prevented multiplication but reduced inoculum CFU by 96 and 100%, respectively, in 72 h. Microscopic studies confirmed killing and digestion of P. brasiliensis ingested by activated macrophages in 48 h. These findings indicate that resident macrophages are permissive for intracellular multiplication of P. brasiliensis and that this could be a factor in pathogenicity. By contrast, activated macrophages are fungicidal for P. brasiliensis.

Changes in lymphocyte subsets following multiple administration of recombinant interleukin-2 plus recombinant interferon-beta or -gamma in tumor-bearing mice

Treatment with a combination of recombinant human interleukin-2 (rHIL-2) and recombinant mouse interferon-beta (rIFN-beta) or -gamma (rIFN-gamma) showed a significant antitumor effect against sc adenocarcinoma 755 in mice, although treatment with either one alone had almost no effect. The combination of rHIL-2 and rIFN-beta caused regression of the tumor but the combination of rHIL-2 and rIFN-gamma did not. Injection of tumor-bearing mice with the combinations of rHIL-2 and rIFN resulted in marked increases in the total number of peritoneal lymphocytes, and the frequency of Lyt-2+ cells was more markedly increased by the combination of rHIL-2 and rIFN-beta than by the combination of rHIL-2 and rIFN-gamma. In Winn assay, elimination of the Lyt-2+ population abolished the protective capacity of the peritoneal cells. The subsets of thymocytes were drastically changed when mice were bearing a tumor or were treated with cytokines. In particular, Lyt-2+/L3T4+ cells were decreased in tumor-bearing mice, but many Lyt-2+/L3T4+ cells were maintained in the thymus by treatment with a cytokine alone. When treated with rHIL-2 and rIFN-beta, the Lyt-2+/L3T4+ cells were markedly decreased, while Lyt-2+/L3T4- T-cells were increased, but these subsets were little changed by treatment with rHIL-2 plus rIFN-gamma. Thus, injections of rHIL-2 and rIFN-beta into tumor-bearing mice resulted in a high frequency of Lyt-2+/L3T4- cells in the peritoneal cavity, together with changes in the T-cell subsets in the thymus. These results suggest that maturation of T-cells in the thymus may be an important step in the pathway by which cytokine treatment brings about regression of tumors.

The effect of gamma interferon on interleukin 1 release of human monocytes. Dependence on the activating agent and correlation to the mRNA levels

The effect of gamma interferon (IFN-gamma) on interleukin 1 (IL-1) production by human monocytes induced either by bacterial lipopolysaccharide (LPS) or silica dust was examined. Release of biologically active IL-1 from LPS-activated monocytes was enhanced in a dose-dependent manner with IFN-gamma. The augmenting effect of IFN-gamma was most marked in monocytes stimulated with a sub-optimal dose of LPS (1 ng/ml). IFN-gamma delivered the augmenting effect only if present at the beginning of the IL-1 induction. The IL-1 released in the presence of IFN-gamma was characterized by gel filtration on fast protein liquid chromatography (FPLC) and by isoelectric focusing; the augmented form of IL-1 was a 17 kDa molecule, with pI 7, i.e. IL-1 beta. In contrast to these data, IFN-gamma had a decreasing effect on IL-1 release by monocytes stimulated with silica dust; in monocyte cultures stimulated with a sub-optimal dose of silica (100 micrograms/ml), only minute amounts of biologically active IL-1 were released in the presence of IFN-gamma. With higher silica concentrations the decreasing effect was less strong. The effects of IFN-gamma on the levels of IL-1 beta mRNA were also analysed. IFN-gamma did not alter the accumulation of IL-1 beta mRNA in LPS-stimulated monocytes. In contrast, in silica-stimulated monocytes IFN-gamma reduced the steady-state levels of IL-1 beta mRNA. Thus, these data indicate that, depending on the stimulating agent, IFN-gamma either down- or up-regulates IL-1 production; the former takes place mainly at the level of transcription, while the latter occurs with post-transcriptional mechanisms.

The effect of interleukin 2 on Fc-gamma receptor function of human monocytes requires specific intercellular interaction

We examined the effect of interleukin 2 (IL 2) on the capacity of human monocytes to secrete reactive oxygen species triggered via Fc-gamma receptor (Fc gamma R) function as measured by chemiluminescence (CL). IL 2 did not activate highly purified (hp) monocytes to respond to Fc gamma R-mediated phagocytic stimulation with an enhanced respiratory burst activity, unless low numbers of T lymphocytes had been cocultured with hp monocytes. The degree of monocyte activation in peripheral blood mononuclear cells (PBMC) by IL2 was dependent on T lymphocytes to monocytes ratios as well as on IL 2 concentrations. Optimal Fc gamma R function was detected with IL 2 concentrations of 60 to 600 U/ml and one to two T lymphocytes per monocyte, whereas higher cellular ratios were suppressive. Supernatants from IL 2-treated PBMC contained interferon-gamma (IFN-gamma) and monocyte activating factor (MAF) activity (= enhanced monocytic Fc gamma R mediated CL). The secretion of both cytokine activities was strongly enhanced by a cooperative function of monocytes. The correlation of IL 2-induced secretion of IFN-gamma and MAF activity was striking; however, monoclonal anti-IFN-gamma antibodies failed to abrogate IL 2-stimulated and lymphocyte-dependent monocyte activation. Although IL 2 had no direct monocyte activating effect, pretreatment of hp monocytes with IL 2 led to a monocyte priming: subsequent coculture with autologous control T lymphocytes enhanced the monocyte Fc gamma R-mediated CL response. The priming of monocytes by IL 2 was dependent on the interaction of IL 2 with the monocytic IL 2 receptor, as shown by inhibition experiments with anti-IL 2 receptor monoclonal antibodies. Thus, we observed an IL 2-driven monocyte/T lymphocyte interaction leading to an increased Fc gamma R-mediated monocytic respiratory burst activity and to the secretion of a soluble MAF activity, but there were no detectable amounts of IFN-gamma.

Enhanced killing of Blastomyces dermatitidis by gamma interferon-activated murine peripheral blood polymorphonuclear neutrophils

Normal peripheral blood polymorphonuclear neutrophils (PB-PMNs), challenged in vitro with yeast form Blastomyces dermatitidis, reduced inoculum colony-forming units of a virulent strain by 37.5 +/- 9.5%. Pre-incubation of PB-PMNs with 10-100,000 U/ml of purified recombinant murine gamma-interferon (IFN) for 1 h prior to challenge with fungi resulted in significant enhancement of PB-PMN fungicidal activity. No direct fungicidal activity by IFN alone was observed. Pretreatment of selected concentrations of IFN shown to have PMN-enhancing activity (100 or 1000 U/ml) with rabbit hyperimmune anti-IFN antiserum for 1 h before addition to PB-PMNs abrogated the enhancement of fungicidal activity. Isolated peripheral blood mononuclear cells failed to kill B. dermatitidis, even when mononuclear cells were present at a concentration ten times greater than that normally used in killing assays, and failed to be activated by IFN. Treatment of unstimulated or IFN-activated PB-PMNs with complement and hybridoma-derived monoclonal antibody specific for PMNs eliminated PB-PMN fungicidal activity. Exogenously added lipopolysaccharide (0.0005-50,000 ng/ml) did not activate PB-PMNs, whether added alone or in conjunction with IFN. The PB-PMN activating capacity of IFN could be destroyed by heat treatment (100 degrees C, 15 min) or by acid treatment with HCl (pH 2). These results demonstrate that recombinant gamma-interferon can stimulate PB-PMNs to kill B. dermatitidis, that the PB-PMN activating moiety is IFN and that PB-PMNs are responsible for fungal killing in this assay system.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of gamma interferon in Mls disparate interactions

The murine T-cell clone E11 isolated from a primary H-2k histocompatible one-way mixed lymphocyte culture of B10.BR anti C3H/Tif spleen cells was used to study multidirectional interactions in strong stimulatory Mls disparate responses. Several parameters have recently been studied, and proliferation of T cells upon stimulation by macrophages or B cells of Mls-disparate stimulator cells, induction of differentiation of B cells of stimulator strains but inhibition of their macrophage differentiation, and the inhibition by E11 T cells of the production of a mitogenic mediator by Mls-disparate spleen cells have been found. As shown in this paper, these phenomena can be explained by an Mlsa, d, e specific induction of gamma-interferon (IFN-gamma) production in the responder B10.BR (Mlsb) E11 T cells. It is suggested that IFN-gamma, as a regulator of feedback mechanisms plays a critical role in Mls disparate T-cell stimulation.

Co-operative effect of MCF and MAF(IFN-gamma) in the protection of mice against Listeria monocytogenes

The effects of macrophage chemotactic factor (MCF) and macrophage-activating factor (MAF) on protection to Listeria monocytogenes were analysed using 'MCF-rich fraction' and murine recombinant interferon-gamma (rIFN-gamma). Recombinant IFN-gamma showed no macrophage chemotactic activity in the assays performed in vitro and in vivo. Although a single injection of either MCF-rich fraction or rIFN-gamma into the footpads of mice led to a significant degree of anti-listerial activity, the highest degree of protection was observed when injected together. The i.v. administration of 20,000 U rIFN-gamma did not raise significant protective activity against Listeria; however, injection with rIFN-gamma prior to that with the MCF-rich fraction into the footpad produced a higher level of protective activity than the group treated with MCF alone. In addition to MAF(IFN-gamma), MCF seems to play another important role in the full expression of protection against L. monocytogenes.

Interferon-gamma-induced alterations of monocyte susceptibility to lysis by autologous lymphokine-activated killer (LAK) cells

Interleukin-2 (IL-2)-activated killer (LAK) cells specifically lyse human monocytes, which may account for some of the toxicity seen during LAK/IL-2 immunotherapy of cancer patients. In an effort to protect autologous monocytes, we treated monolayer cultures of monocytes with various doses of recombinant human interferon-gamma (IFN-gamma) and assessed their sensitivity to LAK-mediated lysis. IFN-gamma lessens the sensitivity of monocytes to lysis in a dose-dependent manner. Treatment of FMEX, an NK-resistant melanoma tumor cell line, with IFN-gamma did not affect its susceptibility to LAK lysis. Kinetic studies demonstrated that as little as 2 hr incubation with IFN-gamma was sufficient for protection to occur, and that monocytes which were treated with IFN-gamma for 2 hr, washed, and then cultured in medium alone retained their resistance to lysis for at least 4 days. Cold target inhibition studies showed that IFN-treated and untreated monocytes could effectively compete with each other for binding sites on LAK cells. Finally, binding studies demonstrated that there was no significant difference between the number of conjugates formed using either IFN-treated or untreated monocytes. This indicates that resistance to lysis induced by IFN treatment affects a post-binding event and not an initial recognition signal.

Induction of tumoricidal macrophages and production of cytokines by synthetic muramyl dipeptide analogues

The ability of various synthetic muramyl dipeptide (MDP) derivatives to induce the production of interleukin-1 (IL-1) and colony stimulating factor (CSF) in vitro and in vivo and to induce cytotoxic macrophages was studied. 6-O-L18-MDP(Me) and MDP-Lys(L18), which were potent inducers of IL-1 and CSF production and of cytotoxic macrophages, had protective activity against Sendai virus infection in mice. In contrast, 1-O-L18-(6-O-P)-MDP(Me) and 2-N-L18-MDP exhibited weak or no ability to induce IL-1 and CSF production and no induction of tumoricidal macrophages, and did not protect against infection of Sendai virus. MDP derivatives, except 2-N-L18-MDP, efficiently rendered macrophages cytotoxic against target cells in the presence of murine recombinant interferon-gamma in vitro. The derivatives that induced cytokines and cytotoxic macrophages appeared to produce anti-viral activity.

Role of gamma interferon in induction of natural killer activity by Legionella pneumophila in vitro and in an experimental murine infection model

Legionella pneumophila has been shown to induce gamma interferon (IFN-gamma) both in vitro and in vivo during experimental infections of mice. With complement-mediated serologic depletion of murine splenocytes, the cellular sources of IFN-gamma following in vitro stimulation with L. pneumophila antigens were Thy-1.2+, Lyt-2-, L3T4-, and asialo-GM1+, which is consistent with the natural killer (NK) cell phenotype. Additionally, Percoll density discontinuous centrifugation demonstrated that maximal production of IFN coincided with high NK activity in fractions which were enriched for large granular lymphocytes. Furthermore, 18- to 24-h incubation of splenocytes with L. pneumophila whole-cell vaccine resulted in augmented NK cytotoxic activity against YAC-1 tumor target cells in a 51Cr release assay. The addition of macrophages to purified large granular lymphocyte populations augmented both IFN-gamma production and NK activity, suggesting that antigen is required for optimal responses. In an experimental infection model using an intratracheal inoculation route, NK activity was enhanced in the spleen, peripheral blood, and lung cells of infected mice, with maximal stimulation in the lung leukocytes at the site of infection. The results of the present study indicate that NK cells respond in vivo and in vitro to stimulation by L. pneumophila by producing IFN-gamma and by increased cytolytic activity.

Multidirectional interactions in an Mls-disparate response

The murine T cell clone E11, isolated from a primary H-2k-histocompatible, one-way mixed lymphocyte culture of B10.BR anti-C3H/Tif spleen cells, has been used to analyse multidirectional interactions in Mls-disparate responses. Several events can be observed. There is proliferation of T cells upon stimulation by macrophages or B cells of Mls-disparate stimulator cells. In addition, one finds induction of differentiation of B cells of stimulator strains. E11 T cells inhibit spreading and differentiation of macrophages of stimulator strains and also prevent the production of a T cell growth-supporting mediator by Mls-disparate spleen cells. All these phenomena can be explained by Mlsa,d,e-specific induction of gamma-interferon (gamma-IFN) production in the responder B10.BR (Mlsb) E11 T cells. It is suggested that gamma-IFN, as a regulator of feedback mechanisms, plays an essential role in Mls-disparate cell interactions.

Synergism between gamma interferon and lipopolysaccharide for synthesis of factor B, but not C2, in human fibroblasts

Four different human fibroblast cell lines synthesized C2 and factor B. Factor B synthesis was increased 12.1-fold by 50 ng/ml LPS and 7.1-fold by 100 U/ml IFN-gamma. C2 synthesis was increased only 2.1-fold by LPS, but 6.4-fold by IFN-gamma. Both LPS and IFN-gamma increased levels of factor B mRNA. LPS induced a 4.7-fold greater increase in factor B protein than in factor B mRNA, whereas IFN-gamma stimulated comparable increases in protein and mRNA. These data suggest that LPS acts to increase factor B synthesis at both pretranslational and translational sites, while IFN-gamma acts primarily at a pretranslational level. In contrast to factor B, increases in C2 protein and C2 mRNA were comparable for both stimuli. A synergistic effect between the two stimuli was observed for factor B only: protein synthesis was increased 54.5-fold or 2.8-fold greater than the additive effects of the stimuli separately. The rate of synthesis in the presence of LPS and IFN-gamma together could not be achieved by increasing concentrations of, or the times of incubation with, either stimulus separately. The synergism was not the result of an increased sensitivity of the cells to either stimulus and was not reproduced by preincubation with one stimulus before incubation with the other stimulus. Several lines of evidence suggest that the synergism, like the stimulation of factor B synthesis by LPS, was dependent on both translational and pretranslational regulation of factor B mRNA. C2 and factor B synthesized in human fibroblasts may play a role in host defense in inflammatory reactions before increases in vascular permeability and recruitment of other complement producing cells.

Gamma-interferon activation of macrophages for killing of Paracoccidioides brasiliensis and evidence for nonoxidative mechanisms

Fungicidal activity of murine peritoneal macrophages for the yeast form of the dimorphic fungal pathogen P. brasiliensis was studied. Killing was assessed by reduction of colony forming units (CFU) using a new medium which has a good plating efficiency. Resident peritoneal macrophages phagocytosed but did not kill P. brasiliensis. Macrophages treated overnight with recombinant gamma-interferon (IFN), lymph node cells plus concanavalin A (Con A) or Con A-stimulated spleen cell culture supernatants (Con A Sup) reproducibly killed three different isolates of P. brasiliensis (35 - 55%, P less than 0.05 - P less than 0.001). This is the first demonstration of killing of this organism by macrophages. Activated macrophages did not show enhanced phagocytosis of P. brasiliensis. Activation of macrophages for killing by IFN was dose-dependent and, varying with the isolate, 100 - 10,000 U/ml was required for inducing significant fungicidal effects against P. brasiliensis. Activation of macrophages by IFN or Con A Sup was abrogated by anti-IFN antibody. These results suggest that immune modulation may be an approach to therapy of paracoccidioidomycosis. Killing was not significantly inhibited in the presence of superoxide dismutase (450 U/ml), catalase (20,000 U/ml), dimethylsulfoxide (300 mM) or azide (1 mM). This indicated that killing mechanism(s) did not depend upon products of the oxidative burst. These results show that P. brasiliensis can be significantly killed by activated macrophages without products of the oxidative burst.

Activation of pulmonary macrophages for fungicidal activity by gamma-interferon or lymphokines

The ability of murine recombinant gamma interferon (IFN) or lymphokines to enhance the fungicidal activity of murine pulmonary macrophages (PuM) was studied in in vitro. PuM monolayers were incubated overnight with IFN, lymph node cells (LNC) plus concanavalin A, supernatants from Con A stimulated LNC or spleen cell cultures (Con A Sup), or tissue culture medium (TCM) +/- Con A (5 micrograms/ml) or +/- lipopolysaccharide (LPS, 10 ng to 10 micrograms/ml). After treatment, culture fluids were removed and PuM were challenged for 4 h with the yeast-form Blastomyces dermatitidis or 2 h with Candida albicans. Inoculum colony forming units (CFU) of B. dermatitidis were significantly reduced by PuM treated with 1000 U/ml of IFN (25 +/- 3%), Con A Sup (25 +/- 3%) or LNC plus Con A (37-44%), but not by TCM, ConA or LPS. Candida albicans was killed by PuM treated with Con A Sup (33 +/- 8%) or LNC plus Con A (30-43%), but not by TCM, Con A, or LPS, and the activity of Con A Sup was neutralized by anti-IFN antibody. Candida albicans was not significantly killed by PuM treated with IFN doses ranging from 1 to 10(5) U/ml; nor did addition of LPS to IFN, or prolonged (3 day) treatment with IFN, result in significant killing of C. albicans by PuM. However, IFN (100 U/ml) could activate resident peritoneal macrophages for significant candidacidal activity (63%). These data indicate that PuM can be activated for fungicidal activity, and that PuM differ from resident peritoneal macrophages with regard to induction of candidacidal activity by recombinant gamma-IFN.

Fungicidal activation of murine macrophages by recombinant gamma interferon

Alveolar macrophages from BALB/c mice readily phagocytized endospores (2 to 5 micron) and arthroconidia of Coccidioides immitis in vitro. Within 24 to 30 h at 37 degrees C, the phagocytized endospores started developing into spherules, and the arthroconidia formed germ tubes and hyphae. However, these processes did not occur if the macrophages were incubated with murine recombinant gamma interferon (rIFN-gamma) during infection with C. immitis. Treatment with rIFN-gamma activated the fungicidal capabilities of the alveolar macrophages, as evidenced by the 50% reduction in the CFU which could be recovered from macrophages infected in the presence of gamma interferon compared with alveolar macrophages infected without gamma interferon (P less than 0.05). Similar results were seen with peritoneal macrophages incubated with rIFN-gamma and infected with C. immitis. As little as 10 U of rIFN-gamma per ml reduced by half the number of C. immitis CFU which could be recovered from the phagocytes 8 h after infection with arthroconidia, although interferon alone did not affect the viability of the fungi.