Role of Th1 and Th2 cytokines in immune response to uncomplicated Plasmodium falciparum malaria

The relative balance between Th1 and Th2 cytokines appears crucial, since the role of cytokines has been evaluated in several studies by comparison of clinically heterogeneous groups of patients. The aim of this study is to determine the role of proinflammatory Th1 cytokines, interleukin-12 (IL-12) and gamma interferon (IFN-gamma), and anti-inflammatory Th2 cytokines, IL-4 and IL-10, in a homogeneous group of patients with uncomplicated Plasmodium falciparum malaria. Levels of IL-12, IFN-gamma, Il-4, and IL-10 in serum for 20 adult patients and 15 healthy control subjects were determined by an immunoenzymatic assay. Serum levels of Th1 cytokines, IL-12 (8.6 +/- 2.8 pg/ml; controls, 3.2 +/- 0.7 pg/ml) and IFN-gamma (39.2 +/- 67.6 pg/ml; controls, 8.4 +/- 6.3 pg/ml), were significantly increased at admission; 3 days later, levels of IL-12 in serum remained significantly high (8.8 +/- 2.6 pg/ml), whereas IFN-gamma levels returned to control values. The anti-inflammatory response of Th2 cytokines (IL-10 and IL-4) was distinct. Levels of IL-10 in serum were not significantly increased at day 0 and day 3 (306.6 +/- 200.4 pg/ml and 56.6 +/- 38.4 pg/ml, respectively; controls, 17.4 +/- 9.0 pg/ml). In contrast, levels of IL-4 in serum were not increased on admission (3.4 +/- 1.2 pg/ml; controls, 2.4 +/- 0.8 pg/ml), but at day 3 a moderate and significant increase of IL-4 levels was observed (4.5 +/- 1.7 pg/ml). In conclusion, the increase of Th1 cytokine IL-12 and IFN-gamma levels during the acute phase of uncomplicated P. falciparum malaria may reflect an early and effective immune response regulated by proinflammatory Th1 cytokines, and in particular IFN-gamma may play a role in limiting progression from uncomplicated malaria to severe and life-threatening complications.     

Serum Cytokines in Patients with Legionella Pneumonia: Relative Predominance of Th1-Type Cytokines

Serum samples from 14 patients with Legionella pneumonia were examined for the presence of cytokines. In spite of high levels of serum C-reactive protein in all patients during the acute phase in only four cases (one involving interleukin-1β [IL-1β], three involving IL-6, and none involving tumor necrosis factor alpha) was the concentration of cytokines more than 100 pg/ml. Th2 cytokines IL-4 and IL-10 were detected in only one patient each. In contrast, significant increases of serum gamma interferon (IFN-γ) and IL-12 levels were observed during the acute phase in 6 and 11 cases, respectively. Interestingly, although serum IFN-γ levels diminished thereafter, in seven cases IL-12 levels remained high or increased further during the convalescent phase. In an additional 22 cases clinically suspected to be but not diagnosed as Legionella pneumonia, increases of serum IL-12 levels were observed in 16 cases, whereas the remaining 6 cases showed no detectable IL-12. Our results demonstrate the relative predominance of Th1 cytokine production in Legionella pneumonia. Although the role and significance of prolonged increases in IL-12 levels in Legionella disease are unknown, our results should prompt further investigation of the host immune response in terms of Th1 and Th2 balance in legionellosis.     

Production of interleukins 10 and 12 by peripheral blood mononuclear cells (PBMC) in chronic hepatitis C virus (HCV) infection

We previously reported that interferon-gamma (IFN-γ) production by PBMC in response to HCV core protein was increased in patients with type C chronic liver disease. To understand better the pathophysiology of this disease, we evaluated production of IL-10 and IL-12 by PBMC from 41 patients with chronic HCV infection, including asymptomatic HCV carriers with persistently normal serum ALT values. IL-10 is known to inhibit many effector functions of the immune system, suppressing Th1-type cell development, while IL-12 stimulates differentiation of Th1-type cells, facilitating cell-mediated immunity. IL-10 production was determined by culturing lymphocytes with concanavalin A (Con A), while IL-12 was produced by monocytes in the presence of Staphylococcus aureusCowan 1 (SAC) with or without recombinant HCV core protein, respectively. The cytokine levels in culture supernatants were measured by ELISA. Spontaneous IL-10 production was greater in patients with chronic hepatitis (CH) (229±119 pg/ml, P<0.01) and liver cirrhosis (LC) (185±88 pg/ml, P<0.05) than in controls (119±27 pg/ml), while it was decreased during IFN treatment (70±25 pg/ml). Both HCV core protein and Con A enhanced IL-10 production by cells from HCV-infected patients. IL-12 was not detectable in medium alone cultures, and SAC-induced IL-12 production did not differ between various patient groups and controls. Simultaneous addition of HCV protein resulted in an increase of IL-12 production in chronic liver disease compared with SAC-alone cultures. Addition of IL-10 to the cultures equally suppressed IFN-γ production for both controls and patient groups, but the enhancing effect of IL-12 on IFN-γ production was significantly less in LC than in controls and other patient groups. The findings suggest that secretion of IL-10/IL-12 by cells from control individuals and various patient groups may be different, and that the cytokines might show different effects on IFN-γ production by some cells.     

Corticosteroids restore the balance between locally produced Th1 and Th2 cytokines and immunoglobulin isotypes to normal in sarcoid lung

In this study, we have investigated the balance between Th1- and Th2-like activity in the lungs in sarcoidosis and have determined the effect of corticosteroid treatment on this. Twenty-one patients with acute untreated sarcoidosis were investigated by bronchoalveolar lavage (BAL) and compared with 11 normal volunteers. Sixteen of the sarcoid patients required corticosteroid therapy and seven of these were reinvestigated after 2–3 months'' treatment. In order to assess Th1- and Th2-like activity in the lungs, IgG subclasses and IgE were measured in BAL fluid and serum, and IL-2, IL-4 and interferon-gamma (IFN-γ) in BAL. In patients with untreated sarcoidosis, albumin-corrected BAL/serum ratios for IgG4 and IgE were significantly reduced (IgG4, 1.04±0.18 (mean±s.e.m.); IgE 9.58±3.11) compared with those in normal controls (IgG4 5.3±0.72, P<0.001; IgE 67.7±28.9, P<0.01). Estimates of actual levels of immunoglobulins produced in the lungs were also made and showed extremely high levels of total IgG in sarcoid patients (39.56±8.2 mg/l ) compared with controls (1.17±0.5 mg/l, P<0.001). Although there was no difference between the groups in amount of IgG4 locally produced, the proportion of total IgG which was IgG4 was greatly reduced in those with sarcoidosis (1.6±0.4% compared with 38.5±3.2%; P<0.001). Lavage levels of IL-4 were also reduced in sarcoid patients (IL-4 2.103±0.21 pg/ml) compared with those in normals (IL-4 6.8±1.05; P<0.001). Levels of IL-2 were lower (7.63±0.51 pg/ml compared with 9.4±0.95 pg/ml), but this difference was not significant. IFN-γ, however, could not be detected above 0.4 pg/ml in any of the normal lavage fluid, but was detectable in 12/21 patients with sarcoidosis (χ²=7.74; P<0.001). These changes reverted towards normal on treatment with oral corticosteroids. The mean albumin-corrected BAL/serum ratio for IgG4 before treatment was 0.88±0.33 compared with 5.5±2.1 (P<0.05) on treatment, and for IgE before treatment 9.52±2.15 compared with 50.8±17.9 (P<0.05) on treatment. Total IgG produced in the lung fell from 26.16±7.9 to 6.12±2.4 mg/l (P<0.001) on treatment, and the proportion of IgG4 locally produced rose from 2.3±0.8% to 23.9±6.1% (P<0.01). The mean level of IL-4 in lavage before treatment was 2.53±0.34 pg/ml compared with 4.7±0.34 (P<0.001) on treatment. Levels of IL-2 also rose significantly on treatment from 8.74±0.95 pg/ml before to 14.44±1.38 pg/ml (P<0.001) on treatment. Levels of IFN-γ fell from 1.65±0.43 pg/ml before treatment to undetectable levels in all patients (P<0.001) on treatment. These results demonstrate an imbalance between Th1- and Th2-like activity in the lungs in sarcoidosis, with suppression of Th2 and increase in Th1. Corticosteroid therapy restores the normal balance between Th1 and Th2 cytokines and immunoglobulins in the lungs, suggesting an effect on local immune regulation.     

Effect of rTsP53 on the M1/M2 activation of bone-marrow derived macrophage in vitro

We investigated that if rTsP53 could be used to activate bone-marrow derived macrophage (BMDM) into M2 macrophage and stop M1 macrophage activation. After 72 h incubation in blank culture medium, cells with PE-CCR7 (-) and FITC-CD206 (-) was extracted and its mean proportion was 92.30 ± 0.22%. With the stimulation of 20 μg/ml IFN-γ for 72 h, cells with PE-CCR7 (+) was extracted and its mean proportion was 16.24 ± 0.82%. With the stimulation of IL-3/IL-14 (both 10 μg/ml) for 72 h, cells with FICT-CD206 (+) was extracted and its mean proportion was 87.32 ± 4.29%. Co-incubation with different dose of rTsP53 (0.001 μg/ml, 0.01 μg/ml, 0.1 μg/ml, 1 μg/ml, 2 μg/ml, 5 μg/ml, 10 μg/ml, respectively) for 72 h, FITC-CD206 (+) macrophage was extracted. The mean proportion in each group was 1.09 ± 0.22%, 2.13 ± 0.13%, 4.91 ± 0.07%, 5.48 ± 0.29%, 9.81 ± 0.06%, 12.83 ± 0.55%, 17.87 ± 0.02%, respectively. The dose of rTsP53 was significantly positive correlated to the proportion of FITC-CD206 (+) macrophage. Co-incubation with 20 μg/ml IFN-γ and 5 μg/ml rTsP53 for 72 h, cells with PE-CCR7 (+) was extracted and its mean proportion was 10.60 ± 0.19%. Compared to that of mere co-incubation with IFN-γ, there was significant difference between the two groups. ELISA showed that Th1 cytokines’ (IFN-γ, IL-6 and TNF-α) level decreased in the culture medium supernatant of BMDM co-incubated with rTsP53. There was negative correlation between the Th1 cytokines’ level and the dose of rTsP53. Both Th2 cytokines (IL-4 and IL-13) and regulatory cytokines in the culture medium increased. There was positive correlation between the Th2 cytokines’ level and the dose of rTsP53. There was also positive correlation between the regulatory cytokines’ level and the dose of rTsP53. Compared to that of BMDM co-incubated with IFN-γ, levels of TNF-α and IL-6 were significant lower than that of BMDM co-incubated with both IFN-γ and rTsP53 (both P < 0.05), while the levels of IL-4 and TGF-β were significant higher (both P < 0.05). There was no significant difference in the levels of IL-13 and IL-10 between the two groups.     

The increased but non-predominant expression of Th17- and Th1-specific cytokines in Hashimoto's thyroiditis but not in Graves' disease

Hashimoto''s thyroiditis (HT) is considered to be mediated mainly by Th1 cells, but it is not known whether Graves'' disease (GD) is associated with Th1 or Th2 predominance. Th17 cells, a novel subset of Th cells, play a crucial role in the pathogenesis of various autoimmune disorders. In the present study, the expression of IL-17A and IFN-γ was investigated in patients with HT or GD. mRNA expression of IL-17A and IFN-γ in peripheral blood mononuclear cells (PBMC) from 43 patients with autoimmune thyroid disease (AITD) and in thyroid tissues from 40 AITD patients were measured by real-time quantitative PCR. The protein expression of IL-17A and IL-23p19 was examined by immunohistochemistry in thyroid tissues from 28 AITD patients. The mRNA levels of IL-17A and IFN-γ were higher in both PBMC and thyroid tissues of HT patients than in controls (mRNA levels are reported as the cytokine/β-actin ratio: IL-17 = 13.58- and 2.88-fold change and IFN-γ = 16.54- and 2.74-fold change, respectively, P < 0.05). Also, the mRNA levels of IL-17A and IFN-γ did not differ significantly in GD patients (P > 0.05). The high protein expression of IL-17A (IOD = 15.17 ± 4.8) and IL-23p19 (IOD = 16.84 ± 7.87) in HT was confirmed by immunohistochemistry (P < 0.05). The similar high levels of IL-17A and IFN-γ suggest a mixed response of Th17 and Th1 in HT, where both cells may play important roles in the destruction procedure by cell-mediated cytotoxicity.     

IMMUNE RESPONSES IN AUTOIMMUNE HEPATITIS: EFFECT OF PREDNISONE AND AZATHIOPRINE TREATMENT: CASE REPORT

The role of the immune response in autoimmune hepatitis has not been studied before and after prednisone and azathioprine treatment. Distributions of blood lymphocytes (CD4+, CD8+, CD19+, CD23+, CD16/56+), levels of serum immunoglobulins (IgM, IgG, IgE, IgA) and cytokines (IFN-γ, IL-4, IL-12, TNFα ) were studied in a child (f/14 y/o) with autoimmune hepatitis before and after prednisone (20 mg/d) and azathioprine (50 mg/d) treatment (nephelometry, UniCAP Total IgE Fluoroenzymeimmunoassay, flow cytometry, cytokine ELISA). Patient was studied for 0-2.5 yrs; treatment was initiated 12 weeks post diagnosis. Numbers of CD4+ T cells increased (50%), while CD19+ and CD23+ cells decreased (>50%) post treatment; other lymphocyte subsets were unaffected by treatment. Serum IgG and IgE levels decreased (>50%) after treatment; serum IgM and IgA were within normal range and were not affected by treatment High levels of IFN-γ (5-23 pg/ml) were initially detected in serum, which decreased after treatment (<0.1 pg/ml). Furthermore, low levels of IL-4 (0.2 pg/mL) were detected before treatment, which were not detected after treatment (<0.1 pg/ml). In contrast, before treatment, IL-12 and TNFα were not detected in serum; however after treatment the levels of IL-12 and TNFα dramatically increased. Prednisone and azathioprine treatment decreased total serum IgG, IgE, IFN-γ and IL-4 levels, and blood CD19+ and CD23+ cells; however serum IL-12, TNFα and blood CD4+ T cells increased with treatment. Understanding immunomodulation in autoimmune hepatitis will provide better insight and mechanisms of this disease and may tailor more effective therapeutic intervention.     

Reciprocal Regulation of Th1- and Th2-Cytokine-Producing T Cells during Clearance of Parasitemia in Plasmodium falciparum Malaria

Flow cytometry for the intracellular detection of T-cell cytokines was performed for 15 Gabonese patients during acute uncomplicated Plasmodium falciparum malaria. A striking expansion of CD4⁺ and CD8⁺ T cells producing gamma interferon (IFN-γ) was found during drug-induced clearance of parasitemia, paralleled by a decrease of interleukin-2 (IL-2) production. The frequency of IL-4- and IL-13-producing CD4⁺ cells gradually decreased, whereas the frequency of T cells producing IL-2⁺–IFN-γ⁺, IL-4⁻–IL-5⁺, and IL-4⁺–IL-5⁺ cytokines as well as IL-4⁺–IFN-γ⁺ and IL-13⁺–IFN-γ⁺ cytokines was not significantly altered. The capacity for IL-10 production within the CD4⁺ subset increased due to an expansion of both IL-10⁺–IFN-γ⁻ and IL-10⁺–IFN-γ⁺ cytokine-expressing cells. Thus, a more pronounced Th2-driven immune response during acute untreated P. falciparum infection with a shift towards Th1 responsiveness induced by parasite clearance is suggested.     

Inactivated Parapoxvirus ovis induces a transient increase in the expression of proinflammatory,Th1-related,and autoregulatory cytokines in mice

The immunostimulatory properties of inactivated Parapoxvirus ovis (iPPVO) have long been investigated in different animal species and experimental settings. In this study, we investigated the effects of iPPVO on cytokine expression in mice after intraperitoneal inoculation. Spleen and sera collected from iPPVO-treated mice at intervals after inoculation were submitted to cytokine mRNA determination by real-time PCR (qPCR), serum protein concentration by ELISA, and interferon (IFN)-α/β activity by bioassay. The spleen of iPPVO-treated animals showed a significant increase in mRNA expression of all cytokines assayed, with different kinetics and magnitude. Proinflammatory cytokines interleukin (IL)-1β, tumor necrosis factor-alpha (TNF-α), and IL-8 mRNA peaked at 24 hours postinoculation (hpi; 5.4-fold increase) and 48 hpi (3- and 10-fold increases), respectively. A 15-fold increase in IFN-γ and 6-fold IL-12 mRNA increase were detected at 48 and 24 hpi, respectively. Increased expression of autoregulatory cytokines (Th2), mainly IL-10 and IL-4, could be detected at later times (72 and 96 hpi) with peaks of 4.7- and 4.9-fold increases, respectively. IFN-I antiviral activity against encephalomyocarditis virus was demonstrated in sera of treated animals between 6 and 12 hpi, with a >90% reduction in the number of plaques. Measurement of serum proteins by ELISA revealed increased levels of IL-1, TNF-α, IL-12, IFN-γ, and IL-10, with kinetics similar to those observed by qPCR, especially for IL-12 and IFN-γ. These data demonstrate that iPPVO induced a transient and complex cytokine response, initially represented by Th1-related cytokines followed by autoregulatory and Th2 cytokines.     

Significantly Higher Cytokine and Chemokine Levels in Patients with Japanese Spotted Fever than in Those with Tsutsugamushi Disease

Tetracyclines are administered to cure Japanese spotted fever (JSF) and tsutsugamushi disease (TD). It is generally said that the clinical course of JSF is worse than that of TD despite antibiotic treatment. The precise mechanism underlying the more severe clinical course of JSF is not fully understood. We therefore examined whether the differential cytokine profile between these two infectious diseases contributes to the difference in clinical severity. The serum concentrations of various cytokines (tumor necrosis factor alpha [TNF-α], interleukin-6 [IL-6], and gamma interferon [IFN-γ]) and chemokines (IL-8, interferon-inducible protein 10 [IP-10], monocyte chemoattractant protein 1 [MCP-1], macrophage inflammatory protein 1α [MIP-1α], MIP-1β, and eotaxin) were measured in 32 TD and 21 JSF patients. The results showed that serum levels of TNF-α in the acute phases of TD and JSF were significantly increased, with a higher concentration of TNF-α in patients with JSF (mean, 39.9 pg/ml) than in those with TD (mean, 13.8 pg/ml). Comparatively higher levels of other cytokines and chemokines (IL-6, IFN-γ, IL-8, IP-10, MCP-1, MIP-1α, and MIP-1β) were also observed in the acute phase of JSF. The clinical severity score (3.67 ± 1.71) of JSF patients was higher than that of TD patients (1.47 ± 0.77). Our findings revealed that the cytokine and chemokine levels in the acute phase of JSF were significantly higher than those in the acute phase of TD. The differential cytokine levels may be related to the difference in clinical severity between JSF and TD.     

Role of Peripheral Blood Mononuclear Cells in the Predisposition of Obese Individuals to Inflammation and Infection

ObjectiveTo compare the production of pro- and anti-inflammatory cytokines by peripheral blood mononuclear cells (PBMC) from obese but otherwise healthy individuals to that of normal-weight volunteers.Methods25 healthy normal-weight subjects and 41 obese individuals were enrolled. Weight and height were measured twice. PBMC were examined for their capacity to generate pro-inflammatory (TNF-α, IFN-γ, IL-1β, IL-6, IL-2) and anti-inflammatory IL-10 and IL-1ra) cytokines.ResultsPBMC from obese individuals, compared to those from subjects with normal weight showed an increased production of the pro-inflammatory cytokines IL-2 (6.7 ± 0.4. vs. 4.9 ± 0.3 ng/ml; p = 0.003), TNF-α (505 ± 45 vs. 277 ± 32 pg/ml; p = 0.001), and IFN-γ (93.8 ± 6.0 vs. 73.9 ± 2.7 ng/ml; p = 0.0016). However, PBMC from obese individuals produced a lower amount of the anti-inflammatory cytokine IL-10 (651 ±72 pg/ml) versus those from subjects with normal weight (951 ± 133 pg/ml; p = 0.039).ConclusionsThe findings imply that obese individuals are in a ‘low-grade inflammatory state’, presumed to be connected with metabolic and cardiovascular co morbidities. The surplus of pro-inflammatory cytokines produced by circulating mononuclear cells of obese individuals, together with those secreted by adipocytes and non-fat cells in the adipose tissue, may contribute to the predisposition of obese patients to inflammation and infections.Key Words: Obesity, Peripheral blood mononuclear cells, Cytokines, Inflammation, Infection     

Serum Cytokine Responses during Acute Human Granulocytic Ehrlichiosis

Human granulocytic ehrlichiosis (HGE) is caused by obligate intracellular bacteria in the Ehrlichia phagocytophila group. The disease ranges from subclinical to fatal. We speculated that cell-mediated immunity would be important for recovery from and potentially in the clinical manifestations of HGE; thus, serum tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), gamma interferon (IFN-γ), IL-10, and IL-4 concentrations were studied. IFN-γ (1,035 ± 235 pg/ml [mean ± standard error of the mean]) and IL-10 (118 ± 46 pg/ml) concentrations were elevated in acute-phase sera versus convalescent sera and normal subjects (P≤0.013 and P≤0.018, respectively). TNF-α, IL-1β, and IL-4 levels were not elevated. Cytokine levels in severely and mildly affected patients were not different. HGE leads to induction of IFN-γ-dominated cell-mediated immunity associated with clinical manifestations, recovery from infection, or both.     

Immunomodulatory Effects of CpG Oligodeoxynucleotides on Established Th2 Responses

CpG oligodeoxynucleotides (CpG ODNs) are known to induce type 1 T-helper-cell (Th1) responses. We have previously demonstrated that CpG ODNs administered during sensitization prevent Th2-mediated eosinophilic airway inflammation in vivo. We also reported that key Th1 cytokines, gamma interferon (IFN-γ) and interleukin 12 (IL-12), are not necessary for this protection. Recent in vivo data suggest that CpG ODNs might also reverse established pulmonary eosinophilia. In order to clarify how CpG ODNs can inhibit established Th2 responses, we evaluated the cytokine production from splenocytes from antigen- and alum-immunized mice. Restimulation with antigen induced IL-5, which was clearly inhibited by coculture with CpG ODNs in a concentration-dependent manner. CpG ODNs also induced IFN-γ, but in a concentration-independent manner. The inhibition of IL-5 production was not mediated through natural killer cells or via CD8⁺ T lymphocytes. Although IFN-γ plays an important role in inhibition of antigen-induced IL-5 production by CpG ODNs, IFN-γ was not the sole factor in IL-5 inhibition. CpG ODNs also induced IL-10, and this induction correlated well with IL-5 inhibition. Elimination of IL-10 reduced the anti-IL-5 effect of CpG ODNs, although incompletely. This may be because IFN-γ, induced by CpG ODNs, is also inhibited by IL-10, serving as a homeostatic mechanism for the Th1-Th2 balance. Overproduction of IFN-γ was downregulated by CpG ODN-induced IL-10 via modulation of IL-12 production. These data suggest that CpG ODNs may inhibit established Th2 immune responses through IFN-γ and IL-10 production, the latter serving to regulate excessive Th1 bias. These properties of CpG ODNs might be a useful feature in the development of immunotherapy adjuvants against allergic diseases such as asthma.     

Gamma Interferon (IFN-γ) and IFN-γ-Inducing Cytokines Interleukin-12 (IL-12) and IL-18 Do Not Augment Infection-Stimulated Bone Resorption In Vivo

Periapical granulomas are induced by bacterial infection of the dental pulp and result in destruction of the surrounding alveolar bone. In previous studies we have reported that the bone resorption in this model is primarily mediated by macrophage-expressed interleukin-1 (IL-1). The expression and activity of IL-1 is in turn modulated by a network of Th1 and Th2 regulatory cytokines. In the present study, the functional roles of the Th1 cytokine gamma interferon (IFN-γ) and IFN-γ-inducing cytokines IL-12 and IL-18 were determined in a murine model of periapical bone destruction. IL-12^−/−, IL-18^−/−, and IFN-γ^−/− mice were subjected to surgical pulp exposure and infection with a mixture of four endodontic pathogens, and bone destruction was determined by microcomputed tomography on day 21. The results indicated that all IL-12^−/−, IL-18^−/−, and IFN-γ^−/− mice had similar infection-stimulated bone resorption in vivo as wild-type control mice. Mice infused with recombinant IL-12 also had resorption similar to controls. IFN-γ^−/− mice exhibited significant elevations in IL-6, IL-10, IL-12, and tumor necrosis factor alpha in lesions compared to wild-type mice, but these modulations had no net effect on IL-1α levels. Recombinant IL-12, IL-18, and IFN-γ individually failed to consistently modulate macrophage IL-1α production in vitro. We conclude that, at least individually, endogenous IL-12, IL-18, and IFN-γ do not have a significant effect on the pathogenesis of infection-stimulated bone resorption in vivo, suggesting possible functional redundancy in proinflammatory pathways.     

Different modulation by histamine of IL-4 and interferon-gamma (IFN-γ) release according to the phenotype of human Th0, Th1 and Th2 clones

Histamine, an important inflammatory mediator in allergic diseases and asthma, has been reported to have modulator effects on T cells, suggesting that the bronchial microenvironment may regulate the function of resident T cells. We examined the effect of histamine on the release of the Th2-associated cytokines IL-4 and IL-5 and the Th1-associated cytokine IFN-γ by 30 CD4⁺ T cell clones from peripheral blood or bronchial biopsy of one atopic subject. Based on the IL-4/IFN-γ ratio, the clones were ascribed to the Th2 (ratio >1), Th0 (ratio 0.1 and 1) or Th1 (ratio <0.1) phenotype. Histamine inhibited IFN-γ production by Th1-like cells (P<0.02, Kruskall–Wallis), especially from bronchial biopsy, but had no effect on IL-4 release. Regarding Th0 clones, histamine inhibited IL-4 production (P<0.02) in a dose-dependent manner and slightly inhibited IFN-γ production, but had no effect on Th2-like cells. Histamine had a heterogeneous and insignificant effect on IL-5 production. The H₂-receptor antagonist ranitidine completely reversed the inhibition of IL-4 and IFN-γ production, whereas the agonist dimaprit mimicked this effect. In contrast, H₁- and H₃-receptor agonists and antagonists had no significant effect. These data demonstrate that histamine has different effects on IL-4 and IFN-γ release by T helper cells according to their phenotype via H₂-receptors. This study extends the immunomodulatory effects of histamine which may contribute to the perpetuation of airway inflammation in asthma.     

Decreased Secretion of Th2 Cytokines Precedes Up-regulated and Delayed Secretion of Th1 Cytokines in Activated Peripheral Blood Mononuclear Cells from Patients with Insulin-Dependent Diabetes Mellitus

Recent evidence suggests that autoimmune animal diabetes is associated with an imbalance between the Th1 and Th2 arms of the cellular immune system. However, limited data is available regarding the Th1/Th2 imbalance in human Insulin dependent diabetes mellitus (IDDM) patients. Therefore, we examined the peak levels, secretory pattern and total cytokine production (calculated as the area under the curve, AUC) of the Th1 cytokines, IL-2 and IFN-γ, and Th2 cytokines, IL-4 and IL-10, from stimulated peripheral blood mononuclear cells, from 17 IDDM patients and 24 normal controls. In contrast to controls, diabetic patients were characterized by an early, uniformly low secretion of Th2 cytokines, followed by a late increased secretion of Th1 cytokines. This resulted in significant differences in secretory patterns of IFN-γIL-2, IL-4 and IL-10 between the two groups;P<0.001,P<0.005,P<0.005 andP<0.001, respectively. No correlation was found in the diabetic patients between any profiles of the cytokines and their various clinical parameters, including age, gender, disease duration, insulin requirements or glycated hemoglobin levels. In conclusion, our data provides the first comprehensive evidence for an independent and persistent impairment of both Th1 and Th2 cytokine secretory patterns in IDDM patients.     

Co-operative action of interleukin-10 and interferon-γ to regulate dendritic cell functions

Interleukin-10 (IL-10) and interferon-γ (IFN-γ) double producer is found in a subpopulation of T regulatory type 1 (Tr1) and T helper type 1 (Th1) cells. Consequently, it is of interest how IL-10 and IFN-γ influence the immune system. However, few studies have addressed the co-operative action of these ‘immunosuppressive’ and ‘immunostimulatory’ cytokines. Here, we examine the effect of IL-10 combined with IFN-γ on dendritic cell (DC) functions. Murine bone marrow-derived conventional DCs were stimulated with IL-10 and/or IFN-γ for 24 hr. Tumour necrosis factor-α and IL-12 p40 production by DCs treated with both IL-10 and IFN-γ was significantly lower than that by DCs treated with IL-10 or IFN-γ alone. Major histocompatibility complex class II expression on DCs treated with both cytokines was attenuated compared with that on DCs treated with either cytokine alone. In contrast, levels of inducible nitric oxide synthase and indoleamine 2,3-dioxygenase, which appear to suppress T-cell responses and promote tolerance, in DCs treated with both cytokines were higher than those in DCs treated with IL-10 or IFN-γ alone. Simultaneous treatment with IL-10 and IFN-γ significantly suppressed the ability of DCs to activate CD4⁺ T cells compared with treatment with either cytokine. Therefore, IL-10 and IFN-γ co-operatively suppress the immunostimulatory functions of DCs.     

Exposure of cord blood to Mycobacterium bovis BCG induces an innate response but not a T-cell cytokine response

Despite routine vaccination with Mycobacterium bovis bacillus Calmette-Guérin (BCG) soon after birth, tuberculosis in babies and adults remains epidemic in South Africa. The immune responses of the naïve newborn child and how they are affected by vaccination with BCG are as yet not fully understood. Immunity during pregnancy and in healthy human newborns may be skewed toward type 2 cytokine production; however, it is type 1 cytokines that are required for protection against M. tuberculosis infection. To better understand neonatal cytokine responses prior to and following exposure to mycobacteria, we have collected cord blood and peripheral blood samples and evaluated the cytokine response following ex vivo incubation with BCG. Gamma interferon (IFN-γ), interleukin 10 (IL-10), IL-12, and low levels of IL-13 and IL-5 but no IL-4 were secreted into the culture supernatant of cord blood mononuclear cells. Intracellular staining showed that IL-10 and IL-12 were produced by monocytes and that IFN-γ was produced by natural killer (NK) cells but not by CD4⁺ or CD8⁺ T cells. In contrast, in the peripheral blood samples collected from babies 13 weeks post-BCG vaccination, IFN-γ was detected within CD4⁺ and CD8⁺ cells. Taken together, the data suggest a central role for Th1 cytokines in naïve as well as BCG-vaccinated neonates in the protective immune response to tuberculosis. NK cell-derived IFN-γ produced in naïve neonates likely plays a key protective role via monocyte activation and the priming of a subsequent adaptive Th1 response.     

An assessment of peripheral immunity in patients with sarcoidosis using measurements of serum vitamin D3, cytokines and soluble CD23

The aetiology of the peripheral anergy in sarcoidosis is unclear. To investigate this further we measured the serum levels of several factors important in different aspects of immune regulation to obtain a profile of those factors which promote and inhibit immune activation in sarcoidosis. Thirty-seven patients with sarcoidosis and 20 healthy controls of similar sex and age comprised the study group. Serum IL-10, interferon-gamma (IFN-γ), soluble CD23 (sCD23), IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1β and tumour necrosis factor-alpha (TNF-α) were measured using in-house ELISAs. Vitamin D3 was measured using a radioreceptor assay. Serum levels of sCD23 and IL-10 were significantly elevated in patients with sarcoidosis relative to controls (median 13.9 versus 9.5 arbitrary units/ml, P < 0.01 for sCD23, and 9.6 versus 5.0 pg/ml, P < 0.04 for IL-10). Regardless of steroid therapy or disease activity, serum levels of IFN-γ, TNF-α, IL-1β, GM-CSF and IL-8 were no different in patients with sarcoidosis and controls. Vitamin D3 levels were significantly higher in patients with sarcoidosis versus normal controls (medians 78.0 versus 56.0, P < 0.001), active sarcoidosis (n = 20) versus inactive disease (n = 17) (medians 81.5 versus 66.0, P < 0.03) and active sarcoidosis versus controls (medians 81.5 versus 56.0, P < 0.0002). The levels were no different between patients with inactive sarcoidosis and controls. We suggest that IL-10 and vitamin D3 may contribute to the peripheral anergy in sarcoidosis. The elevated serum sCD23 suggests an increase in peripheral humoral immunity. Consistent with a quiescent peripheral immune system, factors capable of monocyte/macrophage activation (TNF-α, IFN-γ, GM-CSF and IL-8) were not elevated in the peripheral circulation.     

Elevated plasma levels of IgE in Plasmodium falciparum-primed individuals reflect an increased ratio of IL-4 to interferon-gamma (IFN-γ)-producing cells

People living in Plasmodium falciparum-endemic areas frequently have elevated levels of total as well as P. falciparum-specific serum IgE. This study aimed at investigating whether the elevated serum IgE levels reflect a shift in the balance between CD4⁺ T helper 1 (Th1) and T helper 2 (Th2) cells in individuals naturally exposed to the P. falciparum parasite. To investigate the role of Th1 and Th2 cells in the human P. falciparum system we used the ELISPOT assay to determine the ratio of IFN-γ- and IL-4-producing cells after specific antigen or mitogen activation in vitro. The donors were individuals who had acquired immunity through natural exposure to the parasite. In response to the specific malaria antigens, very few IL-4-producing cells were seen. However, in the response of individual donors to the polyclonal T cell activator, leucoagglutinin (La), the anti-malarial IgE levels in plasma were correlated with an increased ratio of IL-4/IFN-γ producing cells. Thus, donors with ratios of IL-4/IFN-γ > 1 exhibited mean plasma anti-malarial IgE levels significantly greater than those with ratios < 1. In individuals not living in P. falciparum-endemic areas the ratio of IL-4/IFN-γ was always < 1. Taken together, our data suggest a shift in the balance between Th1 and Th2 cells in naturally P. falciparum-primed individuals, associated with elevated anti-P. falciparum plasma IgE levels. The role and biological significance of IgE (Th2-type immune response) for protection against P. falciparum and/or pathogenesis of malaria require further study.