Generation of nitric oxide and induction of major histocompatibility complex class II antigen in macrophages from mice lacking the interferon gamma receptor

Availability of mice with a targeted disruption of the interferon gamma (IFN-gamma) receptor gene (IFN-gamma R0/0 mice) made it possible to examine parameters of macrophage activation in the absence of a functional IFN-gamma receptor. We asked to what extent other cytokines could replace IFN-gamma in the induction of nitric oxide or major histocompatibility complex class II antigen (Ia) expression in peritoneal macrophages. In thioglycollate-elicited macrophages from wild-type mice, tumor necrosis factor (TNF) alone was virtually ineffective in inducing release of NO2- (the endproduct of nitric oxide generation), but TNF enhanced NO2- release in the presence of IFN-gamma. In macrophages from IFN-gamma R0/0 mice, which were unresponsive to IFN-gamma, TNF completely failed to stimulate NO2- release. The stimulatory actions of IFN-alpha/beta on NO2- release were indistinguishable in wild-type and IFN-gamma R0/0 macrophages: IFN-alpha/beta was ineffective on its own, showed marginal stimulation of NO2- release in combination with TNF, and was moderately effective in the presence of lipopolysaccharide. The level of constitutive Ia antigen expression was not significantly different in peritoneal macrophages from wild-type and IFN-gamma R0/0 mice. An increased Ia expression was induced by IL-4 and granulocyte-macrophage colony-stimulating factor in both wild-type and IFN-gamma R0/0 macrophages, but the magnitude of this induction was less than with optimal concentrations of IFN-gamma in macrophages from wild-type mice. IFN-alpha/beta showed only a minor stimulatory effect on Ia expression in both wild-type and IFN-gamma R0/0 macrophages. Simultaneous treatment of wild-type macrophages with IFN-alpha/beta and IFN-gamma reduced the IFN-gamma-induced Ia expression in wild-type macrophages, but IFN-alpha/beta did not show an inhibitory effect on IL-4- or granulocyte-macrophage-colony-stimulating factor-induced Ia expression in either wild-type or IFN-gamma R0/0 macrophages. The important role of IFN-gamma in the regulation of the induced expression of major histocompatibility complex class II antigen was confirmed by showing that after systemic infection with the BCG strain of Mycobacterium bovis resident peritoneal macrophages from IFN-gamma R0/0 mice had a lower level of Ia expression than macrophages from wild-type mice. The inability of other cytokines to substitute fully for IFN-gamma in macrophage activation helps to explain the earlier observed decreased resistance of IFN-gamma R0/0 mice to some infections.     

Novel delivery systems for coagulation proteins

Interferon-alpha (IFN-alpha) is an important molecule in the antiviral response, but cells from HIV-1-infected individuals show a reduced ability to secrete IFN-alpha. We investigated an association between an imbalance of type 1/type2 cytokines and the production of IFN-alpha in HIV-1 infection. We used whole blood culture to study the cytokine production profile, interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), in response to HIV-1 antigens and to study the Sendai Virus and HSV-1-induced-production of IFN-alpha in seven HIV-1-infected patients. An impaired synthesis of IFN-alpha was obtained in patients with a predominant IL-4 production (IL-4 > IFN-gamma), and we found a positive correlation between the ex vivo production of IFN-alpha and the IFN-gamma/IL-4 ratio but not with the HIV RNA copy number in plasma. We investigated the role of T-cell-derived cytokines in the in vitro production of IFN-alpha by PBMC from eight healthy donors, activated with Sendai Virus or HSV-1. Whereas type 2 cytokines (IL-4, IL-13) inhibited virus-induced IFN-alpha synthesis, on the contrary, type 1 cytokines (IL-2, IFN-gamma) enhanced it. A disarray in the T-cell-derived cytokine response may play a role in the defect of IFN-alpha production in HIV-1-infected individuals. Further investigations are needed to explore this hypothesis.     

IFN-gamma increases the severity and accelerates the onset of experimental autoimmune uveitis in transgenic rats

Experimental autoimmune uveitis (EAU) is a predominantly Th1-mediated intraocular inflammatory disease that serves as a model for studying the immunopathogenic mechanisms of uveitis and organ-specific autoimmune diseases. Despite the well-documented role of IFN-gamma in the activation of inflammatory cells that mediate autoimmune pathology, recent studies in IFN-gamma-deficient mice paradoxically show that IFN-gamma confers protection from EAU. Because of the implications of these findings for therapeutic use of IFN-gamma, we sought to reexamine these results in the rat, another species that shares essential immunopathologic features with human uveitis and is the commonly used animal model of uveitis. We generated transgenic rats (TR) with targeted expression of IFN-gamma in the eye and examined whether constitutive ocular expression of IFN-gamma would influence the course of EAU. We show here that the onset of rat EAU is markedly accelerated and is severely exacerbated by IFN-gamma. In both wild-type and TR rats, we found that the disease onset is preceded by induction of ICAM-1 gene expression and is characterized by selective recruitment of T cells expressing a restricted TCR repertoire in the retina. In addition, these events occur 2 days earlier in TR rats. Thus, in contrast to the protective effects of IFN-gamma in mouse EAU, our data clearly show that intraocular secretion of IFN-gamma does not confer protection against EAU in the rat and suggest that IFN-gamma may activate distinct immunomodulatory pathways in mice and rats during uveitis.     

Two cases of severe bacterial meningitis with paranasal sinusitis followed by cerebrovascular disease--pathophysiology and treatment of cerebrovascular disease

We report two cases of pneumococcal meningitis with paranasal sinusitis followed by cerebrovascular disease. Both cases were occupational divers, and had past histories of head trauma and paranasal sinusitis. Despite the combined therapy with antibiotics and dexamethasone, they developed cerebrovascular complications. Case 1 developed cerebral infarction and hemorrhage on day 13, and in case 2 cerebral infarction occurred on day 15. In both cases, serum levels of TNF-alpha and IL-6 were elevated in the early stage of the illness (12 pg/ml and 21.3 pg/ml in case 1, and 50 pg/ml and 7,570 pg/ml in case 2, respectively). In case 2, TNF-alpha, IL-1 beta and IL-6 levels in the cerebrospinal fluid were also elevated on day 4 (25 pg/ml, 320 pg/ml and 6,870 pg/ml, respectively). Thrombocytosis was observed in both cases before the onset of the cerebrovascular complications. These cytokines may play significant roles in thrombocytosis leading to cerebrovascular complications in pneumococcal meningitis. Although the use of steroids as adjunctive therapy for bacterial meningitis has been found to be beneficial, the dosage of dexamethasone administered in our cases may not be enough to suppress the synthesis and release of the cytokines. Therefore, administration of large doses of glucocorticoid should be recommended before the treatment with antibiotics.     

Measuring the quality of outpatient treatment for schizophrenia

OBJECTIVE: Usually it is not possible to study the initial systemic response in patients with acute pancreatitis in the first hours after onset of the disease. We used postendoscopic retrograde pancreatography (ERP) pancreatitis as a model to study cytokine and anticytokine release in the early phase of human acute pancreatitis. METHODS: Post-ERP pancreatitis was defined as a threefold increase in serum amylase and at least two of the following clinical symptoms: abdominal pain, nausea, vomiting or peritonism 24 h after ERP. Serum levels of pro-inflammatory cytokines interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), tumour necrosis factor alpha (TNF), as well as endogenous antagonistic mediators of the systemic inflammatory response such as soluble tumour necrosis factor alpha receptors p55 (TNFR p55) and p75 (TNFR p75), and IL-1-receptor antagonist (IL-1-RA) and interleukin-2-receptor (IL-2R) as indicators of lymphocyte activation were measured before and 0, 1, 4, 12, 24 and 48 h after ERP. In nine patients with acute post-ERP pancreatitis, these parameters were monitored daily until C-reactive protein (CRP) was within normal ranges and were compared to patients without pancreatitis after ERP. RESULTS: IL-1beta was not detectable in five patients with and four patients without post-ERP pancreatitis. The values of the remaining patients in both groups were lower than 3.9 pg/ml. IL-8 and IL-1-RA serum concentrations peaked 12 h after ERP (132.9 and 3245.0 pg/ml respectively) compared to patients without post-ERP pancreatitis (25.8 and 389.9 pg/ml respectively). The IL-6 concentration increased to 81.6 pg/ml (8.0 pg/ml in control patients) 24 h after ERP, while the peak values for CRP were measured 72 h after ERP (164.0 versus 7.7 mg/l). IL-2R content was maximally elevated 144 h after ERP (688.8 versus 255.9 U/ml), while concentrations of TNF and its receptors showed no significant change over time. CONCLUSION: The initial response of the cytokine network to damage of the human pancreas leading to acute pancreatitis includes the release of IL-8 and the IL-1 antagonist IL-1-RA, while IL-1beta is not found in the systemic circulation. The TNF system does not seem to be involved as indicated by the lack of detectable changes in TNF and the soluble TNFR p55 and p75 serum concentrations. Lymphocyte activation as indicated by elevated IL-2R levels occurred days after the initial trauma. Even mild post-ERP pancreatitis leads to significant systemic release of cytokines and their biological counterparts.     

Interleukin-6, gamma interferon, and tumor necrosis factor receptors in typhoid fever related to outcome of antimicrobial therapy

To study mechanisms of antibiotic effects in typhoid fever, levels of interleukin-6 (IL-6), gamma interferon (IFN-gamma), and cytokine receptors (tumor necrosis factor receptor [TNF-R] p55 and TNF-R p75) were measured in the plasma of 29 adult Nepalese with culture-positive typhoid fever before therapy and on days 4 and 15 after start of therapy with either ceftriaxone at 2 g/day for 3 days or chloramphenicol at 50 mg/kg of body weight per day for 14 days. Bacteriologic cure was defined as blood cultures testing negative on days 4 and 15 after start of therapy; clinical cure was defined as symptomatic improvement within 5 days after start of therapy and absence of relapse. Clinical and bacteriologic cures occurred in 24 patients. There were two clinical failures, two patients who failed to complete therapy because of leukopenia, and one relapse. Mean levels before therapy were elevated compared with those in healthy controls (IL-6, 11.4 pg/ml; IFN-gamma, 1.3 ng/ml; TNF-R p55, 3.8 ng/ml; and TNF-R p75, 6.1 ng/ml) and fell progressively during and after therapy. For six patients (three in each treatment group) who showed prolonged fever (> 5 days) or relapse, mean levels of IL-6 and TNF-R p55 before therapy (29.5 pg/ml and 6.1 ng/ml, respectively) and on day 4 (17.7 pg/ml and 4.0 ng/ml) were significantly greater than corresponding means for 23 patients who showed early defervescence (on admission, 6.7 pg/ml and 3.3 ng/ml, and on day 4, 1.8 pg/ml and 2.7 ng/ml, P < .05). These results indicate that the concentrations of plasma cytokines and their receptors are elevated in typhoid fever and that these concentrations can be useful in predicting outcome.     

IFN-gamma-deficient mice develop experimental autoimmune uveitis in the context of a deviant effector response

Experimental autoimmune uveitis (EAU) is a T cell-mediated disease that targets the neural retina and serves as a model of human uveitis. Uveitogenic effector T cells have a Th1-like phenotype (high IFN-gamma, low IL-4), and genetic susceptibility to EAU is associated with an elevated Th1 response. Here we investigate whether the ability to produce IFN-gamma is necessary for the development of EAU by immunizing IFN-gamma-deficient (GKO) mice with the uveitogenic protein interphotoreceptor retinoid binding protein (IRBP) and characterize the associated immunologic responses. GKO mice developed EAU comparable in severity and incidence to that of their wild-type littermates. However, the cytokine profile in their uveitic eyes as well as the cytokines produced by primed lymph node cells in response to IRBP showed a distinct profile: undiminished TNF-alpha and elevated IL-5, IL-6, IL-10, and lymphotoxin (but not IL-4) responses. The inflammatory infiltrate in GKO eyes contained an excess of granulocytes and IL-5- and IL-6-producing cells, but uveitic GKO mice did not up-regulate inducible nitric oxide synthase. GKOs had enhanced lymphocyte proliferation and delayed-type hypersensitivity responses to IRBP. Histology of the delayed-type hypersensitivity lesion in GKO had superimposed elements of an allergic-like response. Anti-IRBP Ab isotypes of GKO mice showed a reduction of IgG2a, but no enhancement of IgG1. Comparison of responses in +/+ and +/- wild-type mice revealed some limited evidence of a gene-dose effect. We conclude that IFN-gamma is not required for priming of pathogenic T cells or for effecting the retinal damage and photoreceptor loss typical of EAU. However, what appears to be a grossly similar disease is caused in the GKO by a deviant type of effector response.     

Release of interleukin-12 in experimental Escherichia coli septic shock in baboons: relation to plasma levels of interleukin-10 and interferon-gamma

Interleukin (IL)-12 is thought to be a key factor for the induction of interferon gamma (IFN-gamma), a cytokine essential for the lethal effects of endotoxin. We report here on the release of the nonfunctional subunit of IL-12, p40, as well as biologically active heterodimeric IL-12, p70, after administration of a lethal (n = 5) or sublethal (n = 8) dose of live Escherichia coli to baboons. Remarkably, on lethal challenge, peak levels of p40 were observed at 3 hours that were about twofold lower than those elicited after sublethal challenge (2,813 +/- 515 pg/mL v 4,972 +/- 732 pg/mL, P < .05). This disparity was also observed, although to a lesser extent, for IL-12 p70 antigen, of which maximum levels of 91 +/- 47 pg/mL and 151 +/- 41 pg/mL were measured 6 hours after a lethal or sublethal dose of E coli, respectively. Circulating p70 antigen correlated with IL-12 biologic activity (r = 0.869; P < .001). When comparing lethal to sublethal conditions, lower peak levels of IL-12 on lethal E coli sharply contrasted with higher levels of other proinflammatory cytokines, such as tumor necrosis factor (TNF)-alpha, IL-1beta, IL-6, and IL-8 observed in these animals. Lower IL-12 concentrations in the lethal group may have resulted in part from the enhanced production of IL-10, a known inhibitor of IL-12 synthesis in vitro, as peak levels of this cytokine 3 hours postchallenge inversely correlated with peak levels of IL-12, in particular p40 (r = -0.802; P < .01). Contrary to what might be expected if IFN-gamma were solely induced by IL-12, lethally challenged baboons generated threefold more IFN-gamma at 6 hours than those receiving a sublethal dose (P < .05). Moreover, higher levels of IFN-gamma were associated with lower p40/p70 ratios, suggesting that, in agreement with observations in vitro, IFN-gamma may have preferentially upregulated the release of p70 over p40. These data show that IL-12 is released in experimental septic shock in nonhuman primates and suggest that IL-10 and IFN-gamma are involved in the regulation of this release. Furthermore, this study indicates that the systemic release of IL-12 might be essential, but is not likely sufficient, to promote lethal production of IFN-gamma in sepsis.     

Cytokine and eosinophil responses in the lung, peripheral blood, and bone marrow compartments in a murine model of allergen-induced airways inflammation

Selective accumulation of eosinophils and activated CD4+ cells is now considered a central event in the pathogenesis of asthma, and this process is thought to be mediated by a number of cytokines including tumor necrosis factor-alpha (TNF-alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), and the Type 2 cytokines interleukin-4 (IL-4) and IL-5. To carry out a detailed time-course analysis of cellular changes in the bronchoalveolar lavage fluid (BAL), peripheral blood (PB), and bone marrow (BM), and of changes in the aforementioned cytokines in BAL and serum, Balb/c mice were sensitized by intraperitoneal injection with ovalbumin (OVA) adsorbed to aluminum hydroxide on two occasions 5 days apart, and were subjected to an OVA aerosol challenge 12 days after the second sensitization. This resulted in an airways inflammatory response characterized by early transient neutrophilia, marked eosinophilia, and, to a lesser extent, lymphocytosis in the BAL. Inflammatory events were first observed 3 h and 24 h after antigen challenge in the lung tissue and BAL, respectively, and lasted for 21 days. In the BM, we detected a 1.5- and 5-fold increase in the total number of cells and eosinophils, respectively, 4 days after the second sensitization. This was followed by a decrease, although BM eosinophilia remained clearly present at the time of antigen challenge. A second eosinopoietic event was observed in the BM shortly after challenge and reached a peak at day 3. BM cellularity returned to normal at day 21 after challenge. Serum OVA-specific IgE was first detected 3 days following the second sensitization (150 ng/ml). IgE levels then decreased but remained at the 75 ng/ml range at the time of the aerosol challenge. During the sensitization period, TNF-alpha (approximately 25 pg/ml), IL-4 (approximately 40 pg/ml), and IL-5 (approximately 250 pg/ml) were detected in serum, but not in the BAL fluid (BALF) and returned to background levels at the time of the antigen challenge. After antigen challenge, TNF-alpha, IL-4, IL-5, and GM-CSF were detected in serum. Peak levels were observed at 3 h (approximately 40 pg/ml), 3 h (approximately 120 pg/ml), 12 h (approximately 350 pg/ml), and 3 h (approximately 10 pg/ml), respectively, and returned to background levels 24 h after challenge. In the BALF, we detected peak levels of TNF-alpha, IL-4, IL-5, and GM-CSF at 6 h (approximately 250 pg/ml), 24 h (approximately 140 pg/ml), 24 h (350 pg/ml), and 3 h (approximately 10 pg/ml), respectively, with a return to background levels 5 days after challenge. No IL-10 could be detected at any time point during sensitization or after challenge in either serum or BAL. We also detected approximately 40 pg/ml of interferon-gamma (IFN-gamma) in the serum of normal untreated mice. Serum IFN-gamma levels fluctuated during sensitization and after challenge, but never exceeded those observed in untreated mice. Thus, the cytokine profile observed in this experimental model of allergic inflammation is characterized by IL-4 and IL-5 dominance, with an apparently minor TNF-alpha and GM-CSF contribution and relatively low or undetectable levels of IFN-gamma and IL-10.     

Effects of interferons on tumour necrosis factor alpha production from human keratinocytes

Interferons (IFNs) have been reported to have pleiotrophic effects including the ability to induce the production of other cytokines in several cell types. Tumour necrosis factor alpha (TNF-alpha) is pro-inflammatory cytokine a known to be produced by a variety of cells including human keratinocytes. In the present study, we sought to determine the effects of IFNs on TNF-alpha production from human keratinocytes. IFN-gamma (50-100 ng/ml) induced TNF-alpha production dose dependently, but no induction of TNF-alpha was observed with IFN-alpha or IFN-beta. Since in the epidermis cytokines often work with in a cascade fashion and keratinocytes are a source of primary cytokine, IL-1 alpha, whether combined treatment with IFN-gamma and IL-1 alpha had a synergistic effect on TNF-alpha production was examined. Combined treatment with IFN-gamma (100 ng/ml) and IL-1 alpha (10 ng/ml) induced 2-3-fold higher level of TNF-alpha than IL-1 alpha alone. These results suggest that IFN-gamma is a positive regulator for the production of TNF-alpha from human keratinocytes and likely to increase skin inflammation.     

Cytokine production regulating Th1 and Th2 cytokines in hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is caused by the hyperactivation of T cells and macrophages. The clinical characteristics associated with this disease result from overproduction of Th1 cytokines including interferon-gamma (IFN-gamma), interleukin-2 (IL-2), and tumor necrosis factor-alpha (TNF-alpha). In this study, we analyzed the production of IL-12 and IL-4, which determine Th1 and Th2 response, respectively, and IL-10, which antagonizes Th1 cytokines, in 11 patients with HLH. IL-12 was detected in plasma in all patients (mean peak value, 30.0 +/- 5.0 pg/mL), while IFN-gamma was massively produced in nine patients (mean peak value, 79.2 +/- 112.0 U/mL). IL-4 was not detected in any of the patients. Plasma IL-10 levels were elevated in all patients (mean peak value, 2,698.0 +/- 3,535.0 pg/mL). There was a positive correlation between the levels of IFN-gamma and IL-10 (P < .01). The plasma concentrations of these cytokines were initially high, before decreasing after the acute phase. However, the decrease in IL-10 levels was slower than that of IFN-gamma. Although the concentration of IL-12 was high at the acute phase, in some patients, a peak in the level was delayed until the chronic phase. Thus, in HLH, production of cytokines that promote development of Th1 cells appears to be predominant over that for Th2 cell development. Overproduction of IL-10 was also observed indicating that a mechanism suppressing hyperactivation of Th1 cells and monocytes/macrophages functions in patients with this disease.     

Mode of action of interleukin-1 in suppression of pituitary LH release in castrated male rats

These studies were undertaken to elucidate the mechanisms whereby the cytokine, Interleukin (IL-1) suppresses pituitary LH release in orchidectomized rats. Since LH secretion is pulsatile in castrated rats, the effects of IL-1 on the components of the LH pulsatility were assessed. Intracerebroventricular (i.c.v.) administration of IL-1 alpha or IL-1 beta suppressed LH release, but IL-1 beta was relatively more effective than IL-1 alpha in terms of the onset (IL-1 beta = 30 min; IL-1 alpha = 105 min) as well as the magnitude and duration of LH suppression. Further, the marked suppression of LH secretion in IL-1 beta-treated rats was found to be due to significant reductions both in the frequency and amplitude of LH episodes. We next evaluated whether the IL-1 beta-induced suppression of LH release was mediated by either of the two inhibitory hypothalamic peptidergic systems, corticotrophin releasing hormone (CRH) and endogenous opioid peptides (EOP). Passive immunoneutralization of CRH by i.c.v. administration of a specific CRH-antibody, either once at 15 min or twice at 75 and 15 min before IL-1 beta injection, failed to block the suppressive effects of IL-1 beta on LH release. Similarly, pharmacological blockade of CRH by i.c.v. injection of the CRH receptor antagonist, alpha-helical CRH9-41 15 min before IL-1 beta was ineffective. However, i.v. infusion of the opiate receptor antagonist, naloxone, which on its own had no effect on LH secretion, counteracted the inhibitory effects of IL-1 beta. To further identify the opiate receptor subtype involved, we utilized specific opiate receptor subtype antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impedance cardiography accurately measures cardiac output during exercise in children with cystic fibrosis

Pro-inflammatory cytokines produced in the central nervous system (CNS) have been suggested to have a role in the anorexia and cachexia of disease. In the present study, the effects of chronic exposure of the CNS to interleukin-1beta (IL-1beta) on several indicators of cachexia were studied. Rats were prepared with an intracerebroventricular (i.c.v.) cannula and an osmotic minipump that delivered vehicle or 1.56 ng/h recombinant murine IL-1beta for 4 days. Food intake and body weight were determined daily during the 4-day infusion period and plasma IL-6 and corticosterone concentrations were determined from plasma collected postinfusion. Chronic i.c.v. infusion of IL-1beta resulted in a chronic reduction in food intake. Rats infused i.c.v. with IL-1beta ate less food each day compared to vehicle controls and, at the end of the 4-day infusion period, consumed an average of 17.2 g less. Intracerebroventricular infusion of IL-1beta also caused an immediate and substantial loss of body weight that was sustained throughout the infusion period. In addition, rats infused with IL-1beta had plasma levels of IL-6 double those of vehicle controls (401 pg/ml vs. 185 pg/ml). Plasma corticosterone concentrations were similar between treatments. These results suggest that chronic exposure of the CNS to cytokines such as IL-1beta may be sufficient to induce anorexia and cachexia.     

Successful immunotherapy of the highly metastatic murine ESb lymphoma with sensitized CD8+ T cells and IFN-alpha/beta

Daily IFN-alpha/beta therapy was totally ineffective in inhibiting the development of visceral metastases in DBA/2 mice injected i.v. with the ESb lymphoma regardless of the number of tumor cells injected. The finding that IFN-alpha/beta therapy increased the survival time of ESb-immunized mice rechallenged with ESb cells suggested that cooperation between the immune system and IFN-alpha/beta was important. Adoptive transfer of Esb-immune spleen cells (but not normal cells) together with IFN-alpha/beta treatment did inhibit the development of ESb metastases in immunocompetent DBA/2 mice. Either treatment alone was ineffective. The anti-metastatic effect was specific for the ESb lymphoma as spleen cells from ESb-immunized mice together with IFN-alpha/beta treatment did not inhibit the development of metastases in mice challenged with IFN-alpha/beta-resistant 3C18 FLC. Depletion of CD8+ T cells (but not CD4+ T cells or B lymphocytes) prior to transfer eliminated the protective effect of ESb-immune splenocytes in IFN-alpha/beta-treated mice. As few as 1 x 10(6) ESb-immune spleen cells highly enriched for CD8+ cells increased the survival time of IFN-alpha/beta-treated ESb-challenged DBA/2 mice. The combined therapy of ESb-specific immune cells and IFN-alpha/beta resulted in long-term immunity to this tumor.     

The role of Stat4 in species-specific regulation of Th cell development by type I IFNs

Type I IFNs (IFN-alpha/beta), in addition to IL-12, have been shown to play an important role in the differentiation of human, but not mouse, Th cells. We show here that IFN-alpha/beta act directly on human T cells to drive Th1 development, bypassing the need for IL-12-induced signaling, whereas IFN-alpha cannot substitute IL-12 for mouse Th1 development. The molecular basis for this species specificity is that IFN-alpha/beta activate Stat4 in differentiating human, but not mouse, Th cells. Unlike IL-12, which acts only on Th1 cells, IFN-alpha/beta can activate Stat4 not only in human Th1, but also in Th2 cells. However, restimulation of human Th2 lines and clones in the presence of IFN-alpha does not induce the production of IFN-gamma. These results suggest that activation of Stat4, which is necessary for the differentiation of naive T cells into polarized Th1 cells, is not sufficient to induce phenotype reversal of human Th2 cells.     

Cytokines induce airway smooth muscle cell hyperresponsiveness to contractile agonists

Inflammatory cytokines have been shown to play an important role in the pathogenesis of various inflammatory processes. In throat infections, intracellular inflammatory cytokines have been detected from the sites of inflammation. The present study aimed to evaluate serum cytokine levels of patients with throat infections and correlate them to the inflammatory parameters and type of inflammation. Significantly higher inflammatory cytokine levels (interleukin [IL]-6 > 7 pg/mL, IL-1 > 1 beta pg/mL, tumor necrosis factor alpha > 1 pg/mL) were detected in most of the patients as opposed to healthy controls. Clinical parameters of infection (fever > 38 degrees C, leukocytosis > 11,000 white blood cells per cubic millimeter, polymorphonuclear neutrophils > 75%) were significantly correlated with high levels of inflammatory cytokines: mainly IL-6 and tumor necrosis factor alpha, and to a lesser degree with IL-1 beta. No correlation, however, was found between the type of inflammation and cytokine levels. The present study indicates a role of inflammatory cytokines in the pathogenesis of throat infections and the need for an anti-inflammatory and anticytokine therapeutic approach.     

IFN-alpha priming of human monocytes differentially regulates gram-positive and gram-negative bacteria-induced IL-10 release and selectively enhances IL-12p70, CD80, and MHC class I expression

Administration of IFN-gamma and IFN-alpha may protect or induce autoimmune diseases. Although the in vitro regulation of monokine secretion by IFN-gamma have been extensively studied, the regulatory function of IFN-alpha has not yet been elucidated. We compared IFN-alpha and IFN-gamma, added alone or simultaneously before bacterial stimulation, for the control of monokine release and the expression of costimulatory molecules by human monocytes. Our data show that: 1) IFN-alpha primes monocytes for increased production of IL-10 in response to Staphylococcus aureus Cowan I strain (SAC) but not to LPS, leading to a lack of IFN-alpha priming for TNF-alpha secretion; 2) pretreatment of monocytes with IFN-alpha inhibits LPS- or SAC-induced IL-12p40 production but unexpectedly enhances the release of the biologically active form of IL-12 (IL-12p70); 3) IFN-alpha and IFN-gamma exert an antagonistic effect on LPS- and SAC-induced IL-10 as well as IL-12p40 release, whereas they further enhance IL-12p70 production when added simultaneously; 4) in contrast to IFN-alpha, IFN-gamma primes monocytes to enhance LPS- or SAC-induced TNF-alpha and IL-12 production, but surprisingly, it increases IL-10 production by monocytes following LPS but not SAC stimulation; and finally, 5) IFN-alpha pretreatment selectively up-regulates CD80 and MHC class I expression on monocytes. It is proposed that the outcome of the immune response at the site of inflammation may depend on both the type of bacterial injury (gram-positive or -negative) and of locally produced IFNs, and that the differential and opposite effects of type I and type II IFNs on monocytes may account for the beneficial or detrimental effects of IFN-alpha therapy.     

Basic surface properties of mononuclear cells from Didelphis marsupialis

The role of IL-10 in the regulation of ocular autoimmune disease was studied in experimental autoimmune uveoretinitis (EAU) elicited in mice by immunization with the retinal antigen interphotoreceptor retinoid binding protein. IL-10-deficient mice were susceptible to EAU, indicating that pathogenesis can occur without presence of IL-10. Treatment of normal mice with IL-10 for 5 days after uveitogenic immunization ameliorated subsequent EAU scores, and down-regulated antigen-specific production of tumor necrosis factor-alpha and IFN-gamma. A concomitant treatment with IL-4 further reduced disease, and resulted in emergence of antigen-specific IL-4 and IL-10 production, as well as in enhancement of the IgG1 antibody isotype. IL-4 by itself was not protective. Only IL-10, but not IL-4, was able to inhibit the function of differentiated uveitogenic T cells in culture. Expression of mRNA for Th1 and Th2 cytokines in the eye during the course of EAU showed that while a Th1 pattern predominated early, IL-10 mRNA expression coincided with down-regulation of the Th1 response and resolution of EAU. Systemic neutralization of IL-10 during the expression phase of EAU resulted in elevated disease scores. Our results suggest that endogenous IL-10 limits expression of EAU and may play a role in the natural resolution of disease. The data further suggest that exogenous IL-10 may be useful in therapeutic control of autoimmune uveitis. While IL-10 by itself is sufficient to suppress Th1 effector development and function, a concomitant administration of IL-4 is required to shift the autoimmune response towards a non-pathogenic Th2 pathway.