Exposure to environmental bacteria may have differing effects on tumour necrosis factor-α and interleukin-6-producing capacity in infancy

Background Our previous study showed an association between increased concentration of endotoxin in house dust and elevated IFN‐γ responses in neonates. The impact of other microbial agents on immune responses in infancy is poorly known. Objective To examine whether stimulated cytokine responses of mothers and their children are associated with concentrations of other microbial markers in addition to endotoxin in house dust samples. Methods Mitogen‐stimulated production of IFN‐γ, IL‐4, IL‐6 and TNF‐α was measured in cord blood and in peripheral blood of mothers (n=29) and their children (n=29) 3 months after birth. Gas chromatography mass spectrometric analysis was applied to measure the concentrations of ergosterol (marker of fungal biomass), muramic acid (indicating the presence of Gram‐positive bacteria) and 3‐hydroxy fatty acids (C_10:0–C_14:0, indicating the presence of Gram‐negative bacteria) in house dust. Endotoxin was determined with Limulus assay. Results Significant mother‐to‐child correlations were observed in stimulated production of TNF‐α and IL‐6 3 months after birth. 3‐hydroxy fatty acid (C_10:0–C_14:0) levels in bed dust were inversely associated with the production of TNF‐α and IL‐6 in blood samples of mothers and their 3‐month‐old children. High concentrations of muramic acid in floor dust were related to increased production of TNF‐α and IL‐6 at the age of 3 months. In contrast to endotoxin, none of the other microbial markers were significantly associated with enhanced IFN‐γ‐producing capacity from birth to 3 months. Conclusions Exposure to Gram‐negative bacteria and their components may be associated with down‐regulated immune responses in early infancy, indicated as an impaired production of pro‐inflammatory cytokines following mitogen stimulation. Gram‐positive bacteria and their constituents seem to have opposite effects. Of the measured markers, exposure to bioactive endotoxin appears to have the strongest impact on T‐helper type 1 responses.     

尘螨诱导新生儿脐血单个核细胞ICOS与转录因子表达的研究

为了解尘螨(HDM)抗原对新生儿脐血单个核细胞(CBMC)及成人外周血单个核细胞(PBMC)CD3+ICOS+细胞阳性率、转录因子T-bet、GATA-3、Foxp3 mRNA表达水平以及培养上清中IL-4、IL-10、IFN-γ表达水平的影响。用流式细胞术,检测新生儿CBMC、成人PBMC体外经PHA和/或HDM抗原刺激前、后CD3+ICOS+细胞阳性率;用RT-PCR法检测细胞体外经PHA和/或HDM抗原刺激前、后T-bet、GATA-3以及Foxp3 mRNA表达水平;用ELISA法,检测细胞在体外经PHA和/或HDM刺激前、后培养上清液中IL-4、IL-10、IFN-γ表达水平。结果表明,高剂量HDM抗原显著下调CBMC经PHA刺激后的CD3+ICOS+阳性率(P<0.05),同时也显著上调PHA刺激前其T-bet mRNA表达(P<0.05),而显著下调该类细胞经PHA刺激后的Foxp3 mRNA的表达(P<0.05)。也显著增加其PHA刺激前的IFN-γ分泌(P<0.01),减少其PHA刺激后IL-10分泌(P<0.05)。高剂量HDM抗原对CBMC的作用强于PBMC,可下调CD3+ICOS+阳性率,显著上调PHA刺激前CBMC T-bet mRNA表达,增加PHA刺激前IFN-γ的分泌,减少PHA刺激后IL-10分泌,提示早期接触高剂量HDM抗原对机体免疫功能的影响较强,可促进新生儿Th1样反应,高剂量HDM抗原可能通过作用于下调Foxp3 mRNA的表达而下调CD4+CD25+调节性T细胞的功能。     

Impairment of lung function might be related to IL-10 and IFN-γ defective production in allergic children

A functional defect of T regulatory cells (Tregs) has been proposed as pathogenic mechanism of allergic reaction. Impairment of lung function frequently occurs in children with respiratory allergy. This study aimed at investigating the possible role of IL-10 and IFN-γ on lung function deterioration in allergic children. Forty children with mild asthma, monosensitized to house dust mites, were evaluated and followed-up for 2 years. Spirometry was performed in all children. IL-10 and IFN-γ were evaluated in in vitro experiments. FEV(1), FVC, and FEF(25-75), evaluated as percent of predicted, significantly diminished over time (p<0.0001, p=0.03, and p<0.0001 respectively). There was a strong relationship between changes in spirometric parameters and IL-10 production and between changes in FEV(1) values and IFN-γ production over time. This preliminary study provided evidence that IL-10 and IFN-γ production could be defective in allergic children prone to develop functional impairment.     

Change in IFN-gamma-producing capacity in early life and exposure to environmental microbes

BACKGROUND: Exposure to environmental microbes in early life might lead to type 1-skewed T cell responses and therefore reduce the risk of allergic diseases. OBJECTIVE: To investigate whether the cytokine responses at birth and at age 3 months are associated with environmental factors, especially exposure to microbes. Living in a farm, level of house dust endotoxin, cleanliness of the home, and presence of cats and dogs in the household were studied as possible determinants of cytokine production. METHODS: Twelve farmers' and 17 nonfarmers' children were studied. Production of IL-4, IL-6, TNF-alpha, and IFN-gamma in cord blood and in peripheral blood at 3 months was measured after 8-hour and 24-hour stimulation with phorbol ester plus concanavalin A. RESULTS: IFN-gamma responses at age 3 months were associated with farming (median, 53 vs 17 pg/mL; P = .019) and cats and dogs (49 vs 14 pg/mL; P = .014) (8 hours). Change in IFN-gamma-producing capacity from birth to 3 months was larger in children with higher than median endotoxin concentration in bed dust (P = .038) and in children with a cat or dog (P = .005) (8 hours). Increased IL-6 responses at birth were associated with cat or dog exposure (P = .004; 8 hours) and endotoxin level in settled dust (P = .039; 24 hours). CONCLUSION: The development of IFN-gamma-producing capacity during the first 3 months of life is associated with farming, endotoxin in house dust, and cat and dog exposure. These environmental characteristics may indicate some microbial exposure capable of driving developing immune system toward T(H)1 responses.     

Sensitization to house dust mites in Reykjavik, Iceland, in the absence of domestic exposure to mites

BACKGROUND: House dust mites are common sources of indoor allergens. In Reykjavik, Iceland, 9% of the young adult population had serum-specific IgE to Dermatophagoides pteronyssinus. Sensitization to mites is usually assumed to be due to exposure to house dust mites in the indoor environment. This investigation was carried out to measure the concentrations of house dust mite allergens and to investigate which species of mites were present in beds in Iceland. METHODS: A total of 197 randomly selected adults were visited at home using the European Community Respiratory Health Survey (ECRHS) II Indoor protocol. Dust samples were collected from mattresses for measurement of house dust mite allergen concentrations and to estimate the number and type of house dust mites. Additional samples from mattresses and floors were collected from the homes of 10 patients with positive skin prick tests (SPT) to D. pteronyssinus. House dust mite allergen concentrations were measured using ELISA and examination of mite species was carried out using microscopy. Climatic parameters were assessed using psychrometer readings in the bedrooms and outdoors. RESULTS: We found two single mite specimens, both D. pteronyssinus, in two dust samples. Mite allergen analyses indicated that two other dust samples had Der f 1 results close to the cut-off of 0.1 microg/g of dust. No samples were positive for Der p 1. In an additional collection of dust from the homes of 10 SPT-positive patients no Dermatophagoides spp. were found. CONCLUSIONS: Reykjavik citizens are exposed to extremely low amounts of house dust mite allergens in their homes. Possible alternative sources for sensitization are discussed, such as bird nests, exposure from travelling abroad, or other mites or invertebrates that cross-react with house dust mite allergens. Our findings suggest that exposures other than to house dust mites indoors are possible sources of mite allergen exposure.     

TLR-mediated distinct IFN-γ/IL-10 pattern induces protective immunity against murine visceral leishmaniasis

Resistance to murine visceral leishmaniasis (VL) correlates with the development of an IFN-γ predominant immune response. Beta1,4-galactose terminal glycans are potent inducers of IFN-γ. Here, we demonstrate the efficacy of a 29 kDa β1,4-galactose terminal glycoprotein (GP29) of Leishmania donovani (LD) in an in vitro macrophage model and an in vivo mouse model of VL. GP29 induced splenic macrophages to release NO and ROS in appreciable amounts that resulted in effective parasite clearance from macrophages. This was associated with the toll-like receptor (TLR)-4 mediated IL-12 induction and inhibition of TLR2-mediated IL-10 production. Two subcutaneous injections of GP29 at fortnightly intervals resulted in dominant IL-12-mediated IFN-γ production and 100% animals were protected against a subsequent challenge with virulent LD parasites. Vaccinated mice showed a reversal of T-cell anergy, significantly elevated expression of iNOS and a type-1 IgG subclass response. Moreover, vaccinated mice downregulated arginase1 and IL-10 expression but did not alter IL-4 expression. The IFN-γ/IL-10 ratio regulated the intensity of the protective immune response. Experiments with IFN-γ and IL-10 knockout mice reiterated the role IL-10 and IFN-γ play in disease progression or resolution in the murine model of VL.     

Flow cytometric determination of cytokines in activated murine T helper lymphocytes: Expression of interleukin-10 in interferon-γ and in interleukin-4-expressing cells

In an immune response, effector functions are controlled by T helper (Th) 1 cytokines [interferon-γ (IFN-γ), interleukin (IL)-2 and tumor necrosis factor-β] and Th 2 cytokines (IL-4, IL-5 and IL-10). Here we analyze by multiparameter immunofluorescence to what extent IL-2, IL-4, IL-5, IL-10 and IFN-γ are co-expressed in individual normal murine Th cells upon activation in vitro with the bacterial superantigen Staphylococcus aureus enterotoxin B, presented in the context of major histocompatibility complex class II. IL-2 and IFN-γ are co-expressed by some, but not by other Th cells. Expression of IL-4 and IFN-γ is exclusive. IL-10 is co-expressed in individual cells either with IL-4 or with IFN-γ. No IL-5-expressing cells are detected. While IL-10- and IL-4-co-expressing Th cells correspond to classical Th 2 cells, cells co-expressing IL-10 and IFN-γ could be involved in negative-feedback regulation of a Th 1 response. Apart from such functional implications, our results show that IL-2, IL-4, IL-5, IL-10 and IFN-γ are expressed independently of each other in individual murine Th cells.     

Age-dependent alterations in serum cytokines,peripheral blood mononuclear cell cytokine production,natural killer cell activity,and prostaglandin F<Subscript>2α</Subscript>

This study aimed to determine age-dependent alterations in serum cytokines, peripheral blood mononuclear cell (PBMC) cytokine production, natural killer (NK) cell activity, and urinary 8-epi-prostaglandin F_2α (PGF_2α). Nine hundred eighty-seven healthy and nonobese subjects were divided into five age groups: 20–34 (group 1), 35–44 (group 2), 45–54 (group 3), 55–64 (group 4), and 65–80 (group 5) years of age. After adjusting for BMI, sex, and smoking and drinking status, serum interferon (IFN)-γ levels decreased in groups 3, 4, and 5 compared with those in groups 1 and 2. Production of IFN-γ by unstimulated PBMCs was lower in the older groups (groups 4 and 5) than in the younger groups (groups 1 and 3). Serum interleukin (IL)-12 was lower in group 5 than in groups 1 and 2. In contrast, both serum and PBMC IL-6 were higher in group 5 than in groups 1, 2, and 3. Urinary 8-epi-PGF_2α increased in group 3 compared with that in group 1 and further increased in group 5. Multiple linear regression analysis revealed that serum IFN-γ levels were negatively affected by age, and NK cell activity at a ratio of E:T = 5:1 was positively affected by PBMC IFN-γ. This study shows the age-related reductions in serum and PBMC IFN-γ and serum IL-12 and age-related increases in serum and PBMC IL-6 and oxidative stress in healthy nonobese subjects. Additionally, circulating IL-6 levels may be a better marker of the chronic low-grade inflammatory activity associated with aging than systemic levels of high-sensitivity C-reactive protein, TNF-α, and IL-1β.     

Cloning and characterization of partial cDNAs for woodchuck cytokines and CD3ϵ with applications for the detection of RNA expression in tissues by RT-PCR assay

Immunologic reagents and methodology are essential to develop further the woodchuck and woodchuck hepatitis virus (WHV) as a model of immune response, inflammation, and immunotherapy in hepatitis B virus (HBV) infection. Partial cDNA clones for the woodchuck CD3ϵ marker of T cells (536 bp) and for selected woodchuck cytokines were developed, including IL-1β (332 bp), IL-2 (249 bp), IL-4 (205 bp), IL-10 (476 bp), IFN-γ (476 bp), and TNF-α (381 bp). This panel of markers includes sets to measure RNAs for T cells (CD3ϵ), immune response induction (IL-1β, IL-2), TH subsets (TH1, IL-2/IFN-γ vs. TH2, IL-4/IL-10), and effector molecules that regulate hepadnavirus replication and liver injury (IFN-γ, TNF-α). Primers representing highly conserved segments of genes from other species were used to derive the partial cDNA clones. Target RNA was obtained from woodchuck peripheral blood mononuclear cells (PBMC) that were stimulated in vitro with ConA, LPS, and human rIL-2. The cDNA clones were validated by 1) comparison with other species for homologies in the nucleotide and predicted amino acid sequences and 2) a first generation assay demonstrating induction of the respective RT-PCR products in stimulated woodchuck PBMC. The corresponding RNAs were also detectable in most cases in the total RNA from the livers of uninfected and WHV-infected woodchucks and differential expression of IFN-γ and TNF-α RNAs was suggested. Second generation, semi-quantitative assays for the RNAs were validated using RT-PCR and dot-blot hybridization with ³²P-oligomers derived from the internal sequences of the respective clones. Continued study of the woodchuck immune response to WHV infection using these assays will provide insight into the kinetics and immune mechanisms that initiate and maintain chronic hepadnavirus infection and, hence, enable development of improved immunotherapies for established chronic HBV infection. J. Med. Virol. 53:85–95, 1997. © 1997 Wiley-Liss, Inc.     

Toll-like receptor 2 ligands inhibit TH2 responses to mite allergen

BACKGROUND: There is intense interest in the interaction between microbial compounds and allergy. Although Toll-like receptor (TLR)-2 ligands derived from Gram-positive bacteria alter allergic sensitization in animal models, it is not clear what effect TLR2 ligands have on allergen-specific T-cell memory in human beings. OBJECTIVE: To determine whether in vitro exposure to TLR2 ligands modifies the immune response to house dust mite allergen (HDM). METHODS: Blood mononuclear cells were obtained from individuals both allergic (n = 23) and not allergic (n = 22) to HDM, and stimulated with HDM in the presence or absence of TLR2 ligands. RESULTS: In subjects allergic to HDM, IL-5 and IL-13 responses to HDM were inhibited by heat-killed Staphylococcus aureus, staphylococcal lipoteichoic acid, and the synthetic lipoprotein Pam3CSK4 (P < .005; all stimuli). Although the whole staphylococcal bacteria increased IFN-gamma responses, the purified TLR2 ligands lipoteichoic acid and Pam3CSK4 inhibited HDM-specific IFN-gamma synthesis. In contrast, TLR2 ligands had minimal effects on responses to HDM in subjects without allergy. TLR2 ligands induced upregulation of HLA-DR expression but did not inhibit antigen uptake or processing by antigen-presenting cells. CONCLUSION: Toll-like receptor 2 ligands inhibit allergen-specific T(H)2 responses in sensitized individuals. This effect appears to be mediated by the actions of TLR2 ligands on antigen-presenting cells, and at least for the purified TLR2 ligands does not involve the induction of a strong T(H)1 immune response. CLINICAL IMPLICATIONS: These findings provide an impetus for further preclinical studies examining the potential use of TLR2 ligands in allergic disease.     

乙型肝炎疫苗联合B7-H1蛋白疫苗对HBV转基因小鼠抗HBsAg免疫应答的影响

目的:研究B7-H1蛋白疫苗对HBV转基因小鼠免疫应答的影响,探索治疗慢性乙型肝炎的新方法。方法:用不同剂量的乙型肝炎疫苗和B7-H1蛋白疫苗联合免疫HBV转基因小鼠,应用ELISA法检测转基因小鼠在不同时间点血清抗B7-H1抗体滴度,同时在免疫后第14周末处死小鼠取脾细胞,检测不同的免疫方法对小鼠脾细胞产生HBsAg特异性Th1类细胞因子(IFN-γ及IL-2)、对HBsAg特异性分泌IFN-γT细胞数量及对小鼠淋巴细胞增殖的影响。结果:成功完成小鼠的免疫计划,5周起血清中即能测到B7-H1抗体,同一时间点各组之间的抗体滴度值并无明显差异。加B7-H1蛋白免疫各组与相同剂量单用HBsAg蛋白免疫各组相比:IL-2均明显减低(P<0.05),分泌IFN-γT的T细胞数量下降,但脾淋巴细胞分泌IFN-γ的水平各组间无明显差异;MTT法测定的淋巴细胞增殖能力各组间也无明显变化。结论:B7-H1蛋白疫苗可诱导HBV转基因小鼠产生明显的抗B7-H1抗体应答,但不能增强抗HBsAg的免疫应答。较小剂量的HBsAg即可引起HBV转基因小鼠Th1类细胞因子(IFN-γ及IL-2)的分泌以及淋巴细胞增殖。     

两种MHC-B单倍型鸡群在发育过程中四种细胞因子转录水平的变化

目的:从分子水平探讨鸡免疫系统的个体发生学。方法:利用双重荧光定量RT-PCR(dqRT-PCR)技术,对14～35日龄主要组织相容性复合体(MHC)单倍型鸡品系G2(B15单倍型)和G5系(B5单倍型)鸡群的肺组织(包括气管)、脾脏和外周血淋巴细胞(PBL)中IFN-γ、IL-18、IL-4和IL-10的mRNA含量进行定量检测。结果:随日龄增长,两鸡群脾脏中IFN-γ转录水平升高,PBL中IL-18和IL-10整体下降。G5系鸡群脾脏中IFN-γ转录水平始终高于肺组织和PBL。两鸡群脾脏中IL-18转录水平均高于肺组织和PBL,脾脏中IL-4在孵化后早期转录水平较高,而肺组织中则出现较晚。两鸡群肺组织、脾脏和PBL中IL-10均在35日龄降到最低。结论:14～35日龄无特定病原体(SPF)鸡脾脏中IFN-γ转录水平随生长发育而增多,而肺组织和PBL中未见明显随生长发育变化的规律;PBL中IL-18和IL-10转录水平随生长发育而下降;18～35日龄,肺组织、脾脏和PBL中IL-10转录水平均随日龄增长而降低;不同MHC-B单倍型鸡群细胞因子转录水平受日龄调节相似。     

House dust mite immunotherapy results in a decrease in Der p 2-specific IFN-γ and IL-4 expression by circulating T lymphocytes

Background Allergen-specific immunolherapy (IT) can be an important adjunctive therapy in the treatment of allergic disorders. Although it has now been used for over 80 yr. the precise mechanism of action remains unclear. Recently a number of studies have shown that cytokine production may be modified by IT, but different protocols have been used and different results obtained. Objectives The aims of the present study were: (1) lo document the allergen-specific expression of intcrleukin-4 (IL-4) and interferon-γ (IFN-γ) by peripheral blood cells in both untreated house dust mite (HDM) allergic patients(non-lT) and following at least 10 months of HDM-specific IT (post-IT); and (2) to determine whether alterations in these critical regulatory cytokines correlated with the clinical outcome of IT. Methods IT was undertaken with nine fortnightly subcutaneous injections of increasing amounts of a Dertnatophagoides pteronyssinus (Dpt) extract, reaching a final dose of 10000 PNU. This was followed by 6- to 8-monthly maintenance injections of 5000 PNU. For cytokine measurement, mononuclear cells were separated from peripheral blood and stimulated with the major Dpt allergen, Der p 2. for 18 h, after which mRNA was isolated and IL-4 and IFN-γ cDNA were amplified by polymerase chain reaction (PCR). The presence of the particular cytokine was determined by visualization following clcctrophoresis on an agarose gel. The study was observational in nature being open and without a placebo group. Results Fifteen Dpt-sensitive patients who had not received HDM IT (non-IT), and 16 who had, were studied. In the non-IT group. 80% expressed IL-4 and 75% expressed IFN-γ. In those post-IT, only 12.5% expressed IL-4 and 19% IFN-γ. The two patients still expressing IL-4 post-IT had had very little clinical response. Six patients were studied both pre- and post-IT. Prior to IT, three were positive for both cytokines, two positive for IL-4 alone and one for IFN-γ. Post-IT, all six were negative for IL-4 and five were negative for IFN-γ. Conclusion Allergen-specific IT results in a reduction in expression of the critical eytokines IL-4 and IFN-γ in circulating lymphocytes. It is possible that this is a contributary mechanism in the beneficial effect of IT.     

Borrelia species induce inflammasome activation and IL-17 production through a caspase-1-dependent mechanism

Borrelia burgdorferi spirochetes cause Lyme disease, which can result in severe clinical symptoms such as multiple joint inflammation and neurological disorders. IFN-γ and IL-17 have been suggested to play an important role in the host defense against Borrelia, and in the immunopathology of Lyme disease. The caspase-1-dependent cytokine IL-1β has been linked to the generation of IL-17-producing T cells, whereas caspase-1-mediated IL-18 is crucial for IFN-γ production. In this study, we show by using knockout mice the role of inflammasome-activated caspase-1 in the regulation of cytokine responses by B. burgdorferi. Caspase-1-deficient cells showed significantly less IFN-γ and IL-17 production after Borrelia stimulation. A lack of IL-1β was responsible for the defective IL-17 production, whereas IL-18 was crucial for the IFN-γ production. Caspase-1-dependent IL-33 played no role in the Borrelia-induced production of IL-1β, IFN-γ or IL-17. In conclusion, we describe for the first time the role of the inflammasome-dependent caspase-1 activation of cytokines in the regulation of IL-17 production induced by Borrelia spp. As IL-17 has been implicated in the pathogenesis of chronic Lyme disease, these data suggest that caspase-1 targeting may represent a new immunomodulatory strategy for the treatment of complications of late stage Lyme disease.     

The value of perinatal immune responses in predicting allergic disease at 6 years of age

BACKGROUND: Characterizing early abnormalities in immune development of allergic individuals provides an important basis for defining disease pathogenesis and future prevention strategies. This study compares patterns of early immune responses in an established cohort based on allergic outcomes and allergen skin prick test (SPT) reactions at 6 years of age. METHODS: Children from an original birth cohort (n = 60) consisting of 44 high risk (HR) (family history of allergy) and 16 low risk (LR) (no family history) were reassessed at 6 years of age. Detailed clinical information about allergic disease was obtained (n = 53) and a subgroup (n = 31) consented to have allergen SPT to common food and inhalant allergens. Data from previous immunological assessments performed at birth, 1 and 2 years of age, including lymphoproliferation and cytokine [interleukin (IL)-4, IL-5, IL-6, IL-10, IL-13 and interferon (IFN)-gamma] responses to ovalbumin (OVA), house dust mite (HDM), cat allergen (Fel d 1), phytohaemaglutinin (PHA) and tetanus toxoid, were re-analysed based on the 6-year clinical outcomes. RESULTS: Twenty-eight HR and three LR children had a clinical history of allergic disease at 6 years of age including doctor diagnosed asthma (n = 17) and/or eczema (n = 24). Most children (78%) with atopy at 6 years had positive SPT to the allergens tested, and 70% had symptoms within the last year. Children at genetic risk (family history) of allergy had weaker (P = 0.017) polyclonal T helper 1 (Th1) IFN-gamma responses in the neonatal period compared with LR children. Although children with allergic disease at 6 years also tended to have weaker neonatal IFN-gamma responses compared to those with no symptoms, but this was not quite significant (P = 0.05). A positive SPT to HDM at 6 years was associated with higher IL-13 responses to HDM at 1 year (P = 0.02), whereas allergic disease at 6 years was associated with higher IL-5 messenger RNA (mRNA) responses to HDM at 1 year (P = 0.01). Despite these associations, regression analysis demonstrated that the only significant early predictors of allergic sensitization at 6 years of age were a family history of allergic disease, and atopic symptoms at 2 years. Importantly, none of the early immunological parameters measured were significantly predictive of allergic disease or allergic sensitization in these 6-year-olds. CONCLUSIONS: Although our observations suggest that subtle differential alterations in cytokine responses during early immune development are associated with different aspects of subsequent atopy, there are still no early predictive biomarkers of disease. A positive family history of allergy remains the dominant predictive factor.     

Interleukin-12 is required for interferon-γ production and lethality in lipopolysaccharide-induced shock in mice

Several cytokines, in particular tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), have been shown to be responsible for pathological reactions which may lead to shock and death observed in infection with Gram-negative bacteria and in response to endotoxins (lipopolysaccharides, LPS). Priming of mice with the avirulent Bacille Calmette Guérin (BCG) vaccine strain of Mycobacterium bovis increases the sensitivity of mice to the lethal effect of LPS and results in an efficient priming for cytokine production. In response to low doses (1 γg/mouse) of LPS, BCG-primed mice produce interleukin-12 (IL-12) which controls IFN-γ production, as demonstrated by the ability of neutralizing anti-IL-12 antibodies to suppress IFN-γ production. However, the concentration of the biologically active IL-12 p70 heterodimer is similar in the serum of both BCG-primed or unprimed mice, reaching levels of 1–3 ng/ml at 3–6 h after LPS injection, whereas IFN-γ production was observed only in BCG-primed mice. The priming effect of BCG on IFN-γ production appears to be mostly due to its ability to increase TNF-α production, which acts as cofactor with LPS-induced IL-12 in inducing IFN-γ production, as shown by the ability of injection of TNF-α and LPS (1 γg/mouse), but not LPS alone, to induce IFN-γ production. However, in addition to TNF-α, other LPS-induced cofactor(s) are required in cooperation with IL-12 to induce optimal IFN-γ production, because co-injection of TNF-α and IL-12, sufficient to induce serum concentrations of both cytokines higher and more persistent than those obtained by injection of LPS, was not sufficient to induce IFN-γ production in vivo. Neutralizing anti-IL-12 antibodies, in addition to inhibiting the in vivo LPS-induced IFN-γ production, also completely protect BCG-primed mice injected with up to 10 μg of LPS from shock-induced death. Thus, IL-12 is required for IFN-γ production and lethality in an endotoxic shock model in mice.     

绿脓杆菌制剂与IL-12在诱导人NK细胞IFN-γ产生中的协同作用

探讨绿脓杆菌制剂(piliated Pseudomonas Aeruginosa,PPA)与IL-12协同诱导人PBMC和NK细胞IFN-γ的产生。分离健康人PBMC和纯化NK细胞分别与培养液、PPA、IL-12或PPA+IL-12共同培养,利用酶联免疫吸附法(ELISA)检测无细胞培养上清中IFN-γ的水平。同时采用流式细胞仪在单个细胞水平上分析PPA和IL-12诱导IFN-γ产生的淋巴细胞亚群。结果显示,单独应用亚适剂量的IL-12或PPA刺激人PBMC或纯化NK细胞,不能诱导或只能诱导低水平IFN-γ的产生。当PPA和IL-12共同与人PBMC或纯化NK细胞孵育后,PPA呈时间和剂量依赖性与IL-12协同诱导PBMC和纯化NK细胞产生大量IFN-γ。细胞亚群分析的结果表明,PPA和IL-12协同诱导CD56+NK细胞产生IFN-γ,但对CD4+T和CD8+T细胞无明显作用。PPA与IL-12协同促进NK细胞IFN-γ的产生,提示PPA和IL-12能直接刺激NK细胞发生免疫应答。