Disease-specific ex vivo stimulation of whole blood for cytokine production: applications in the study of tuberculosis

A novel whole blood assay to quantify the release of T cell associated cytokines in response to Bordetella pertussis antigens

BACKGROUND

Bordetella pertussis continues to cause whooping cough globally even in countries with high immunisation coverage. Booster vaccinations with acellular pertussis vaccines are thus used in children, adolescents, and adults. T cell immunity is crucial for orchestrating the immune response after vaccination. However, T cell assays can be expensive and difficult to implement in large clinical trials. In this study, a whole blood (WB) stimulation assay was developed to identify secreted T cell associated cytokines in different age groups after acellular pertussis booster vaccination.

MATERIAL AND METHODS

Longitudinal WB samples were collected from a small set of subjects (n = 38) aged 7-70 years participating in a larger ongoing clinical trial. For assay development, samples were diluted and incubated with purified inactivated pertussis toxin (PT), filamentous haemagglutinin (FHA), inactivated B. pertussis lysate, and complete medium (M) as stimulating conditions, with anti-CD28 and anti-CD49d as co-stimulants. Different timepoints around the vaccination (D0, D7, D14, D28), WB dilution factor (1:2, 1:4) and incubation time (24 h, 48 h, 72 h) were compared. Responses to 15 cytokines were tested with Luminex/multiplex immunoassay.

RESULTS

The optimized assay consisted of WB incubation with M, PT, and FHA (including the two co-stimulants). After 48 h incubation, supernatants were collected for measurement of seven selected T cell associated cytokines (IL-2, IL-5, IL-10, IL-13, IL-17 A, IL-17F, and IFN-y) from samples before and 28 days after vaccination. PT stimulation showed a trend for upregulation of IL-2, IL-13, and IL-17 A/F for adult subjects, whereas the responses of all cytokines were downregulated for the paediatric subjects. Furthermore, PT and FHA-stimulated WB showed diverse cytokine producing profiles.

CONCLUSIONS

The developed WB-based cytokine assay was shown to be less costly, easy to perform, and functional in differently aged individuals. Further, it requires only a small amount of fresh blood, which is beneficial especially for studies including infants. Our results support the use of this assay for other immunological studies in the future.

Early Clearance of Mycobacterium tuberculosis Is Associated With Increased Innate Immune Responses

BACKGROUND

A proportion of tuberculosis (TB) case contacts do not become infected, even when heavily exposed. We studied the innate immune responses of TB case contacts to understand their role in protection against infection with Mycobacterium tuberculosis, termed "early clearance."

METHODS

Indonesian household contacts of TB cases were tested for interferon-γ release assay (IGRA) conversion between baseline and 14 weeks post recruitment. Blood cell populations and ex vivo innate whole blood cytokine responses were measured at baseline and, in a subgroup, flow cytometry was performed at weeks 2 and 14. Immunological characteristics were measured for early clearers, defined as a persistently negative IGRA at 3 months, and converters, whose IGRA converted from negative to positive.

RESULTS

Among 1347 case contacts, 317 were early clearers and 116 were converters. Flow cytometry showed a resolving innate cellular response from 2 to 14 weeks in persistently IGRA-negative contacts but not converters. There were no differences in cytokine responses to mycobacterial stimuli, but compared to converters, persistently IGRA-negative contacts produced more proinflammatory cytokines following heterologous stimulation with Escherichia coli and Streptococcus pneumoniae.

CONCLUSIONS

Early clearance of M. tuberculosis is associated with enhanced heterologous innate immune responses similar to those activated during induction of trained immunity.

Immune cell characteristics and cytokine responses in adult HIV-negative tuberculous meningitis: an observational cohort study

Immunopathology contributes to high mortality in tuberculous meningitis (TBM) but little is known about the blood and cerebrospinal fluid (CSF) immune response. We prospectively characterised the immune response of 160 TBM suspects in an Indonesian cohort, including 67 HIV-negative probable or definite TBM cases. TBM patients presented with severe disease and 38% died in 6 months. Blood from TBM patients analysed by flow cytometry showed lower αβT and γδT cells, NK cells and MAIT cells compared to 26 pulmonary tuberculosis patients (2.4-4-fold, all p < 0.05) and 27 healthy controls (2.7-7.6-fold, p < 0.001), but higher neutrophils and classical monocytes (2.3-3.0-fold, p < 0.001). CSF leukocyte activation was higher than in blood (1.8-9-fold). CSF of TBM patients showed a predominance of αβT and NK cells, associated with better survival. Cytokine production after ex-vivo stimulation of whole blood showed a much broader range in TBM compared to both control groups (p < 0.001). Among TBM patients, high ex-vivo production of TNF-α, IL-6 and IL-10 correlated with fever, lymphocyte count and monocyte HLA-DR expression (all p < 0.05). TBM patients show a strong myeloid blood response, with a broad variation in immune function. This may influence the response to adjuvant treatment and should be considered in future trials of host-directed therapy.

IGF1 potentiates the pro-inflammatory response in human peripheral blood mononuclear cells via MAPK

Acromegaly is characterized by growth hormone (GH) and insulin-like growth factor 1 (IGF1) excess and is accompanied by an increased cardiovascular diseases (CVD) risk. As innate immune responses are crucial in CVD development, and IGF1 is linked to subclinical inflammation, we hypothesized that GH/IGF1 excess contributes to CVD development by potentiating systemic inflammation. We aimed to assess the effects of GH/IGF1 on inflammatory cytokine production. Whole blood from acromegaly patients and healthy volunteers and peripheral blood mononuclear cells (PBMCs) from healthy volunteers were stimulated with Toll-like receptor (TLR) ligands, with or without adding GH or IGF1 (in PBMC). Cytokine concentrations were measured by ELISA. The underlying signalling pathways were investigated by the inhibition of downstream targets of the IGF1 receptor. The following results were obtained. GH or IGF1 alone did not influence cytokine production in PBMCs. GH did not affect TLR-induced cytokine production, but co-stimulation with IGF1 dose dependently increased the TLR ligand-induced production of IL6 (P < 0.01), TNF alpha (P = 0.02) and IFNg (P < 0.01), as well as the production of the anti-inflammatory cytokine IL10 (P = 0.01). IGF1 had no effect on IL1B, IL17 and IL22 production. Inhibition of the MAPK pathway, but not mTOR, completely abrogated the synergistic effect of IGF1 on the LPS-induced IL6 and TNF alpha production. In whole blood of acromegaly patients, ex vivo IL6 production was increased (P < 0.01). In conclusion, IGF1, but not GH, has pro-inflammatory effects, probably via the MAPK signalling pathway and might be involved in the pathogenesis of atherosclerosis in acromegaly. The increased IL10 production possibly counteracts the pro-inflammatory effects.

Innate Immune Responses to Tuberculosis

Tuberculosis remains one of the greatest threats to human health. The causative bacterium, Mycobacterium tuberculosis, is acquired by the respiratory route. It is exquisitely adapted to humans and is a prototypic intracellular pathogen of macrophages, with alveolar macrophages being the primary conduit of infection and disease. However, M. tuberculosis bacilli interact with and are affected by several soluble and cellular components of the innate immune system which dictate the outcome of primary infection, most commonly a latently infected healthy human host, in whom the bacteria are held in check by the host immune response within the confines of tissue granuloma, the host histopathologic hallmark. Such individuals can develop active TB later in life with impairment in the immune system. In contrast, in a minority of infected individuals, the early host immune response fails to control bacterial growth, and progressive granulomatous disease develops, facilitating spread of the bacilli via infectious aerosols. The molecular details of the M. tuberculosis-host innate immune system interaction continue to be elucidated, particularly those occurring within the lung. However, it is clear that a number of complex processes are involved at the different stages of infection that may benefit either the bacterium or the host. In this article, we describe a contemporary view of the molecular events underlying the interaction between M. tuberculosis and a variety of cellular and soluble components and processes of the innate immune system.

Immunological response to Mycobacterium tuberculosis infection in blood from type 2 diabetes patients

The convergence of tuberculosis and diabetes represents a co-epidemic that threatens progress against tuberculosis. We have investigated type 2 diabetes as a risk factor for tuberculosis susceptibility, and have used as experimental model whole blood infected in vitro with Mycobacterium tuberculosis. Blood samples from diabetic patients were found to have a higher absolute neutrophil count that non-diabetic controls, but their immune functionality seemed impaired because they displayed a lower capacity to phagocytose M. tuberculosis, a finding that had been previously reported only for monocytes. In contrast, an increased production of TNFα was detected in infected blood from diabetic patients. Despite the altered phagocytic capacity showed by cells from these patients, the antimicrobial activity measured in both whole blood and monocyte derived macrophages was similar to that of controls. This unexpected result prompts further improvements in the whole blood model to analyze the immune response of diabetes patients to tuberculosis.

Inter-individual variability and genetic influences on cytokine responses to bacteria and fungi

Little is known about the inter-individual variation of cytokine responses to different pathogens in healthy individuals. To systematically describe cytokine responses elicited by distinct pathogens and to determine the effect of genetic variation on cytokine production, we profiled cytokines produced by peripheral blood mononuclear cells from 197 individuals of European origin from the 200 Functional Genomics (200FG) cohort in the Human Functional Genomics Project (http://www.humanfunctionalgenomics.org), obtained over three different years. We compared bacteria- and fungi-induced cytokine profiles and found that most cytokine responses were organized around a physiological response to specific pathogens, rather than around a particular immune pathway or cytokine. We then correlated genome-wide single-nucleotide polymorphism (SNP) genotypes with cytokine abundance and identified six cytokine quantitative trait loci (QTLs). Among them, a cytokine QTL at the NAA35-GOLM1 locus markedly modulated interleukin (IL)-6 production in response to multiple pathogens and was associated with susceptibility to candidemia. Furthermore, the cytokine QTLs that we identified were enriched among SNPs previously associated with infectious diseases and heart diseases. These data reveal and begin to explain the variability in cytokine production by human immune cells in response to pathogens.

Cytokine signatures of human whole blood for monitoring immunosuppression

How to evaluate status of the immune system is extremely critical for clinical immunosuppressive treatment. In this study, we tested the secretion of cytokines in undiluted whole blood samples stimulated with Phorbol 12-myristate 13-acetate (PMA) and ionomycin (IONO), and compared the effects of dexamethasone (DEX), cyclosporine A (CsA) or mycophenolic acid (MPA), either alone or in combination, on cytokine profiles. The results showed that both DEX and CsA dose-dependently inhibited the production of eleven cytokines: interleukin (IL)-2, IL-4, IL-5, IL-6, IL-13, IL-17, interferon γ (IFN-γ), tumor necrosis factor α (TNF-α), granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF). Unexpectedly, MPA showed no obvious influences except for the mild inhibition on GM-CSF production. In combination treatment, cytokine profiles reflect not only the synergistic effects among drugs, but also the specific effect of the individual drug. Thus, the effects of different immunosuppressants could be reflected through their specific cytokine signatures, which can be applied to maximize immunosuppressive effects, while to minimize risk of infections and help physicians to reasonably apply immunosuppressants.

Assessment of serum level of interleukin-1b and interleukin-12 in leprosy: impact of previous Bacillus Calmitte Guerin vaccination

Macrophages play an important role in attempt to eliminate mycobacteria, via production of cytokines, including interleukin-1, and interleukin-12. Bacillus Calmitte Guerin (BCG) vaccination, known to induce interleukin-1β in tuberculosis, was originally aimed at tuberculosis control, but it showed efficacy against leprosy. Our aim was to estimate serum levels of interleukin-1β and interleukin-12, in leprosy, and to assess the impact of previous BCG vaccination on their levels. Serum interleukin-1β and interleukin-12 p70 were estimated in 43 leprotic patients and 43 controls by enzyme-linked immunosorbent assay. Patients were grouped according to presence or absence of reactions, as well as bacillary load. Serum interleukin-1β was significantly higher in patients as compared to controls (p = 0.047), and was significantly different in patients' groups (p = 0.036); with significantly higher level in multibacillary patients, both non reactional and with erythema nodosum leprosum, compared with paucibacillary/non reactional patients (p = 0.012 and 0.049 respectively). A statistically significant higher interleukin-1β was found in BCG vaccinated paucibacillary patients as compared to unvaccinated patients (p = 0.031). Significantly elevated interleukin-12 was present in patients as compared to controls (p < 0.001), with no statistically significant difference comparing patients' groups. BCG vaccination showed stimulatory effect on monocytes only in the immunocompetent paucibacillary leprosy patients, as evidenced by higher Interleukin-1β in this group. Interleukin-1β was shown to have a pro-inflammatory role in multibacillary patients with or without erythema nodosum leprosum. Targeting interleukin-1β may be promising to control episodic refractory erythema nodosum leprosum. Interleukin-12 may be a general marker of active Mycobacterium leprae infection.

Early clearance of Mycobacterium tuberculosis: a new frontier in prevention

Early clearance (EC) is the successful eradication of inhaled Mycobacterium tuberculosis before an adaptive immune response develops. Evidence for EC comes from case contact studies that consistently show that a proportion of heavily exposed individuals do not develop M. tuberculosis infection. Further support for the existence of this phenotype comes from genetic loci associated with tuberculin reactivity. In this review we discuss aspects of the innate response that may underpin EC and hypotheses that can be tested through field laboratory link studies in M. tuberculosis case contacts. Specifically, we consider mechanisms whereby alveolar macrophages recognize and kill intracellular M. tuberculosis, and how other cell types, such as neutrophils, natural killer T cells, mucosa-associated invariant T cells and cd T cells may assist. How EC may be impaired by HIV infection or vitamin D deficiency is also explored. As EC is a form of protective immunity, further study may advance the development of vaccines and immunotherapies to prevent M. tuberculosis infection.

Pattern recognition receptors and cytokines in Mycobacterium tuberculosis infection--the double-edged sword?

Tuberculosis, an infectious disease caused by Mycobacterium tuberculosis (Mtb), remains a major cause of human death worldwide. Innate immunity provides host defense against Mtb. Phagocytosis, characterized by recognition of Mtb by macrophages and dendritic cells (DCs), is the first step of the innate immune defense mechanism. The recognition of Mtb is mediated by pattern recognition receptors (PRRs), expressed on innate immune cells, including toll-like receptors (TLRs), complement receptors, nucleotide oligomerization domain like receptors, dendritic cell-specific intercellular adhesion molecule grabbing nonintegrin (DC-SIGN), mannose receptors, CD14 receptors, scavenger receptors, and FCγ receptors. Interaction of mycobacterial ligands with PRRs leads macrophages and DCs to secrete selected cytokines, which in turn induce interferon-γ- (IFNγ-) dominated immunity. IFNγ and other cytokines like tumor necrosis factor-α (TNFα) regulate mycobacterial growth, granuloma formation, and initiation of the adaptive immune response to Mtb and finally provide protection to the host. However, Mtb can evade destruction by antimicrobial defense mechanisms of the innate immune system as some components of the system may promote survival of the bacteria in these cells and facilitate pathogenesis. Thus, although innate immunity components generally play a protective role against Mtb, they may also facilitate Mtb survival. The involvement of selected PRRs and cytokines on these seemingly contradictory roles is discussed.

Inflammatory mediators influence the expression of nociceptin and its receptor in human whole blood cultures

BACKGROUND

Nociceptin/orphanin FQ and its receptor (NOP) are involved in immune responses, inflammation and pain processing. The aim of this study was to investigate the modulation of NOP and prepro-nociceptin (PNoc), the precursor of nociceptin, by inflammatory mediators in human whole blood.

METHODS

Peripheral blood from healthy volunteers was cultured for 0, 3, 6 and 24 hrs with or without lipopolysaccharide (LPS), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-10 or interferon (IFN)-γ. NOP and PNoc mRNA of peripheral white blood cells were detected by quantitative RT-PCR. Cytokine concentrations in supernatants of whole blood cultures were measured using ELISA. In addition, an intervention experiment using anti-cytokine antibodies was conducted to evaluate possible mechanisms involved in the modulation of NOP and PNoc by LPS. The primary goal was to investigate NOP and PNoc mRNA expression in human peripheral blood under inflammatory conditions.

RESULTS

LPS significantly suppressed NOP (median area under the mRNA-expression-time curve (1(st)/3(rd) quartile): 5.4 (4.6/6.6) normalized ratio · hr) and PNoc expression (40.8 (34.4/49.5)) compared to baseline measures (NOP: 22.7 (17.1/25.3); PNoc: 69.9 (58.4/89.2), both p<0.001). LPS incubation induced cytokine concentrations (TNF-α, IL-1β, IL-10 and IFN-γ) in whole blood cultures. Incubation with TNF-α, IL-1β, IL-10 or IFN-γ decreased NOP mRNA levels to varying extents (p<0.05 for all). In contrast, PNoc mRNA expression was decreased by IL-10 only (p = 0.018). The LPS effect on NOP expression could be antagonized by anti-TNF-α and anti-IL-1β, whereas anti-IL-10 and anti-INF-γ had no effect. There was no change of PNoc expression when LPS induced cytokines were antagonized by the respective antibodies.

CONCLUSIONS

LPS as well as cytokines suppress mainly NOP and, in part, PNoc mRNA expression in human whole blood cultures. This may represent a negative feedback loop to the previously described upregulation of cytokines by PNoc.

T4 phage and its head surface proteins do not stimulate inflammatory mediator production

Viruses are potent activators of the signal pathways leading to increased cytokine or ROS production. The effects exerted on the immune system are usually mediated by viral proteins. Complementary to the progress in phage therapy practice, advancement of knowledge about the influence of bacteriophages on mammalian immunity is necessary. Particularly, the potential ability of phage proteins to act like other viral stimulators of the immune system may have strong practical implications for the safety and efficacy of bacteriophage therapy. Here we present studies on the effect of T4 phage and its head proteins on production of inflammatory mediators and inflammation-related factors: IL-1α, IL-1β, IL-2, IL-6, IL-10, IL-12 p40/p70, IFN-γ, TNF-α, MCP-1, MIG, RANTES, GCSF, GM-CSF and reactive oxygen species (ROS). Plasma cytokine profiles in an in vivo mouse model and in human blood cells treated with gp23*, gp24*, Hoc and Soc were evaluated by cytokine antibody arrays. Cytokine production and expression of CD40, CD80, CD86 and MHC class II molecules were also investigated in mouse bone marrow-derived dendritic cells treated with whole T4 phage particle or the same capsid proteins. The influence of T4 and gp23*, gp24*, Hoc and Soc on reactive oxygen species generation was examined in blood cells using luminol-dependent chemiluminescence assay. In all performed assays, the T4 bacteriophage and its capsid proteins gp23*, gp24*, Hoc and Soc did not affect production of inflammatory-related cytokines or ROS. These observations are of importance for any medical or veterinary application of bacteriophages.

Serum levels of leptin in Nigerian patients with sickle cell anaemia

Background

Several studies have shown that the pathophysiology of homozygous sickle cell anaemia (SCA) results in a myriad of metabolic, nutritional, haematological and clinical effects that interact with other co-morbid factors to determine the quality of life and life expectancy of afflicted patients. Because of its critical roles in nutrition and metabolism, inflammation, haematopoiesis and cellular immunity, this study determined the plasma levels of leptin in steady and unsteady states of HbSS in Nigerian patients.

Methods

A total of 51 SCA patients aged 5 - 35 years with 34 (61.8%) being females who were either on admission or visiting four medical centres in Lagos, Nigeria together with 22 non-SCD controls aged 5 -30 years comprising 12 (54.5%) females were enrolled after obtaining their informed consent and ethical approval. Patients were further stratified into steady and unsteady cases of SCA based on clinical presentations, while blood samples collected by venipuncture from each of the study participants were analyzed haematologically for full blood count and HbF level and microscopically for malaria, while plasma leptin was assayed using ELISA method. Body composition defined by weight, fat mass and body mass index (BMI) was determined using standard methods. Data obtained for cases and controls were analyzed statistically.

Results

Twenty - one patients had unsteady HbSS and elicited greater and significant (P < 0.05) reduction in fat mass, BMI, HbF and eosinophil count but elevated mean total leukocyte, count, level of irreversibly sickled cells and P. falciparum parasitaemia (4613.7 vs. 749.6 - 1078.4 parasites/uL), pyrexia rate (58.3 vs. 25.8%) when compared with steady state patients or non-SCD controls. Compared to the control, significant decreases in plasma leptin before and after controlling for body fat that was worsened by crisis were observed among the SCD patients. Unlike the non-SCD controls, leptin correlated non-significantly (P > 0.05) with all body composition indices measured in the patients except for fat mass in unsteady cases. Multivariate regression analysis identified ESR and RC as independent predictor of low plasma leptin concentration in the SCA patients.

Conclusions

Base on these findings, we conclude that plasma level of leptin is further decreased in the unsteady state of HbSS, shows poor correlation with adiposity and malarial infection but has inflammation and poor reticulocyte response as independent predictors among Nigerian patients.

A single dose of vitamin A improves haemoglobin concentration, retinol status and phagocytic function of neutrophils in preschool children

Since there is a reported interrelationship between vitamin A and Fe metabolism, and with immunological response, the objective was to evaluate the effect of a single dose of vitamin A administered to preschool children, on Fe and vitamin A nutritional status, anaemia and phagocytic function of neutrophils, 30 d after supplementation. A total of eighty children (sixty-eight supplemented and twelve controls) were supplemented orally with 200 000 IU (60 mg) vitamin A, and evaluated for nutritional, haematological and immunological responses at the beginning of the study and 30 d after supplementation. Parameters studied included Hb, serum ferritin, retinol and Fe concentrations, transferrin saturation, IL-4, interferon-γ and phagocityc capacity of neutrophils using non-fluorescent latex microbeads. After supplementation there was a significant increase in Hb concentration (P = 0·03), mean corpuscular Hb concentration (P = 0·001) and serum retinol (P = 0·0078). Prevalences of anaemia and vitamin A deficiency decreased significantly from 17·6 % to 13·2 % and from 25 % to 13·2 %, respectively. Regarding phagocytic function, there was a significant increase in the number of microbeads engulfed by neutrophils (P < 0·05) and no significant changes in cytokine concentrations at 1 month after treatment. A single dose of 200 000 IU (60 mg) vitamin A administered orally to a group of preschool children with a high prevalence of vitamin A deficiency enhanced serum retinol and Hb concentrations, decreased the prevalence of anaemia and vitamin A deficiency and improved the constitutive phagocytic capacity of neutrophils. Vitamin A supplementation could help to decrease vitamin A deficiency, anaemia prevalence and to improve the innate immunity response in preschool children. The effects were obtained without Fe supplementation.

A randomized, placebo-controlled study of the effects of the p38 MAPK inhibitor SB-681323 on blood biomarkers of inflammation in COPD patients

The p38 mitogen-activated protein kinase (MAPK) signaling upregulates inflammation and is known to be increased in chronic obstructive pulmonary disease (COPD). The authors assessed the pharmacology of the novel p38 MAPK inhibitor SB-681323 using blood biomarkers in COPD. Seventeen COPD patients (forced expiratory volume in 1 second 50%-80% predicted) using short-acting bronchodilators participated in a double-blind, double-dummy, randomized, crossover study. Patients received single oral doses of SB-681323 7.5 mg and 25 mg, prednisolone 10 mg and 30 mg, and placebo. Blood was obtained predose and at 1, 2, 6, and 24 hours postdose. Whole-blood sorbitol-induced phosphorylated (p) heat shock protein (HSP) 27 levels as a marker of p38 pathway activation and lipopolysaccharide-induced tumor necrosis factor (TNF)-alpha production were assessed. Both doses of SB-681323, but not prednisolone, significantly (P < .0001) reduced weighted mean (WM) pHSP27 (0-6 hours) by 58% compared with placebo. WM TNF-alpha production (0-24 hours) was significantly reduced compared with placebo by SB-681323 25 mg (40%, P = .005) and 7.5 mg (33.4%, P = .02), while prednisolone 30 mg and 10 mg caused 81.5% and 58.2% suppression, respectively (both P < .0001). SB-681323 inhibited the p38 MAPK pathway to a greater degree than prednisolone did. SB-681323 inhibited TNF-alpha production. SB-681323 is a potent p38 MAPK inhibitor that potentially suppresses inflammation in COPD.

Modulation of muramyl dipeptide stimulation of cytokine production by blood components

Muramyl dipeptide (MDP) is the minimal active fragment of peptidoglycan of the cell wall of Gram-positive bacteria, with potential beneficial effects as a vaccine adjuvant. Peptidoglycans and MDP are recognized by the intracellular receptor NOD2 (nucleotide-binding oligomerization domain 2), leading to production of proinflammatory cytokines. In the present study, it is shown that, despite stimulatory effects on isolated human mononuclear cells, MDP does not stimulate production of tumour necrosis factor-alpha, interleukin-1beta or interleukin-6 in a whole-blood assay. However, MDP retains synergistic effects on lipopolysaccharide-induced cytokines in whole blood. Screening tests of NOD2 function based on whole-blood stimulation should therefore employ strategies based on the synergistic effects of MDP on Toll-like receptor-induced cytokine production. Plasma was not responsible for the inhibition of MDP in whole blood. The inhibition of MDP stimulation was dependent upon cellular components, with erythrocyte-derived haemoglobin and neutrophils collaborating in the inhibition of MDP effects in whole blood.

Endotoxin hypersensitivity in chronic heart failure

BACKGROUND

Raised concentrations of endotoxin (lipopolysaccharides, LPS) have been demonstrated in patients with chronic heart failure (CHF). Tolerance of monocytes to LPS can be induced by negative feedback mechanism through LPS itself, resulting in a downregulation of cytokine response to LPS challenge. As endotoxin desensitization has also been suggested for CHF, we investigated the response to LPS challenge in CHF patients.

METHODS

We prospectively studied 100 patients with CHF (62 +/- 13 years) and 21 controls (58 +/- 10 years, LVEF 60 +/- 3%). HLA-DR expression and TNFalpha generation of monocytes after ex vivo stimulation by LPS (stimulation with LPS 50 and 500 pg/ml) were determined. 46 CHF patients were in NYHA class II (LVEF 29 +/- 8%) and 54 in NYHA class III (LVEF 27 +/- 7%).

RESULTS

HLA-DR expression in controls (25,837 +/- 7915 ABS/cell) was comparable to CHF NYHA II patients (23,720 +/- 8488 ABS/cell, n.s.), but lower in patients classified NYHA III (20,327 +/- 5073 ABS/cell, p < 0.01). Stimulated TNFalpha production ex vivo was higher in CHF NYHA III (LPS 50: 437 +/- 284; LPS 500: 946 +/- 500 pg/ml, each p < 0.05) and CHF NYHA II (LPS 50: 397 +/- 277; LPS 500: 933 +/- 483 pg/ml, each p < 0.05) compared to controls (LPS 50: 315 +/- 134; LPS 500: 715 +/- 339 pg/ml).

CONCLUSIONS

In chronic heart failure TNFalpha generation capacity increases while HLA-DR expression decreases compared to controls. Thus patients with CHF display enhanced susceptibility to inflammatory stimuli.

Cytokine response to antigen stimulation of whole blood from patients with Mycobacterium ulcerans disease compared to that from patients with tuberculosis

Mycobacterium ulcerans disease (Buruli ulcer) is a skin-ulcerating infection common in some parts of the tropics. We have investigated cytokine secretion after stimulation of whole blood from Buruli ulcer (BU) patients in a region of endemicity in Ghana with M. ulcerans sonicate or culture filtrate antigens to investigate the development of the response over time and its specificity by comparison with the response to Mycobacterium tuberculosis sonicate in human immunodeficiency virus-negative tuberculosis patients. Significant gamma interferon (IFN-gamma) production in response to whole-blood stimulation with M. ulcerans sonicate was detected in patients with ulcers, which was higher than that in patients with nodules but similar to subjects with healed BU. The mean IFN-gamma response in household contacts of BU patients was not significantly different from that in healthy control subjects from an area of nonendemicity. Results in patients with untreated, smear-positive pulmonary tuberculosis and tuberculosis patients on treatment for more than 2 weeks showed that BU patients responded better to M. ulcerans antigens than tuberculosis patients. In contrast, interleukin-10 results were higher in patients with active M. ulcerans disease than in those with healed lesions, but the pattern of response was similar to that seen in tuberculosis. A similar pattern of cytokine secretion was found using M. tuberculosis sonicate as an antigen. Neither of the two culture filtrate antigens of M. ulcerans appeared to be more specific than M. ulcerans sonicate. In the early stages of M. ulcerans disease there was a mixed Th1 and Th2 cytokine response, but the Th1 response emerged as the dominant type.

Comparative pathogenicity of bacteraemic isolates of Aeromonas hydrophila and Klebsiella pneumoniae

Two bacteraemic isolates of Aeromonas hydrophila and Klebsiella pneumoniae, Ah-2743 and Kp-129, respectively, were studied for their relative pathogenicity in comparison with Escherichia coli ATCC 25922. Ah-2743 caused significantly higher serum levels of tumour necrosis factor-alpha, interleukin (IL)-1beta or IL-6 in human whole blood, and higher serum IL-1beta and IL-6 levels in infected mice, than did Kp-129 and E. coli ATCC 25922. In addition, in BALB/c mice infected by intraperitoneal inoculation, Ah-2743 caused a higher fatality rate (80%) than did Kp-129 (0%). With intramuscular inoculation, Ah-2743 caused more rapid and intense local accumulation of inflammatory cells than did Kp-129, and myonecrosis was present only in Ah-2743-infected mice. These data indicate that Ah-2743 is more pathogenic than Kp-129 or E. coli ATCC 25922 for BALB/c mice. The cellular components or extracellular factors associated with increased cytokine induction and pathogenicity of A. hydrophila in mice merit further investigation.

Cytokine production of stimulated whole blood cultures in rheumatoid arthritis patients receiving short-term infliximab therapy

Patients with rheumatoid arthritis (RA) treated with anti-tumor necrosis factor (TNF) strategies have an increased susceptibility to infections, especially those caused by intracellular pathogens. In this study we assessed the cytokine production capacity in patients with RA and we further investigated whether anti-TNF therapy modulates the production of pro-inflammatory cytokines involved in the resistance against infections. Whole blood cultures from 10 RA patients and 10 healthy controls were stimulated with heat-killed Candida albicans, Salmonella typhimurium, Staphyloccocus aureus, Aspergillus fumigatus or Mycobacterium tuberculosis and production of interleukin (IL)-1beta, IL-6, IL-10, interferon (IFN)-gamma and TNF-alpha was measured. Before anti-TNF therapy, whole blood cultures from RA patients released significantly less IFN-gamma than healthy controls after stimulation with all tested microorganisms. Short-term anti-TNF therapy did not have an inhibitory effect on the release of the cytokines tested. We conclude that cells of patients with RA have a strongly reduced production capacity of IFN-gamma after bacterial challenge. Although short-term therapy with anti-TNF agents did not further decrease the release of other proinflammatory cytokines, the combination of defective IFN-gamma production in basal conditions and TNF neutralization during anti-TNF therapy is likely to be responsible for the higher susceptibility to infections in patients with RA.

Reduced production of immunoregulatory cytokines in vitamin A- and zinc-deficient Indonesian infants

OBJECTIVE

To determine effects of vitamin A, zinc and iron deficiency in Indonesian infants on the ability to produce immunoregulatory cytokines.

DESIGN, SETTING AND SUBJECTS

Immunological assessment was done in 59 infants participating in a cross-sectional nutritional survey in rural West Java, Indonesia. Production of T-helper cell type-1 (Th1, cell-mediated) cytokines interferon-gamma (IFN-gamma), interleukin-12 (IL-12), interleukin-18 (IL-18) and T-helper cell type-2 (Th2, humoral) cytokine interleukin-6 (IL-6) were measured after stimulation with lipopolysaccharide and phytohemagglutinin in an ex vivo whole blood culture system. Circulating neopterin concentrations were determined as an indicator of in vivo macrophage activity.

RESULTS

Of the infants, 48% were vitamin A deficient, 44% were anemic (with 17% having iron deficiency anemia), and 17% were zinc deficient. Vitamin-A deficient infants had significantly reduced ex vivo production of IFN-gamma, but also significantly higher circulating neopterin concentrations. Production of IFN-gamma and IL-12 were strongly correlated, IFN-gamma and IL-18 production were not. Zinc deficiency was accompanied by significantly reduced white blood cell counts and reduced ex vivo production of IL-6. Iron status was not related to cytokine production.

CONCLUSIONS

This study shows that in vitamin A deficiency there is Th1 dominance in a steady state, combined however with impairment of the Th1 response after stimulation, whereas in zinc deficiency, there is a decreased Th2 response. Overall, vitamin A deficiency and zinc deficiency have marked albeit different effects on the immunocompetence of infants, affecting both cell-mediated and humoral components of the immune system.

Bacillus Calmette Guerin triggers the IL-12/IFN-gamma axis by an IRAK-4- and NEMO-dependent, non-cognate interaction between monocytes, NK, and T lymphocytes

The IL-12/IFN-gamma axis is crucial for protective immunity to Mycobacterium in humans and mice. Our goal was to analyze the relative contribution of various human blood cell subsets and molecules to the production of, or response to IL-12 and IFN-gamma. We designed an assay for the stimulation of whole blood by live M. bovis Bacillus Calmette-Guerin (BCG) alone, or BCG plus IL-12 or IFN-gamma, measuring IFN-gamma and IL-12 levels. We studied patients with a variety of specific inherited immunodeficiencies resulting in a lack of leukocytes, or T, B, and/or NK lymphocytes, or polymorphonuclear cells, or a lack of expression of key molecules such as HLA class II, CD40L, NF-kappaB essential modulator (NEMO), and IL-1 receptor-associated kinase-4 (IRAK-4). Patients with deficiencies in IL-12p40, IL-12 receptor beta1 chain (IL-12Rbeta1), IFN-gammaR1, IFN-gammaR2, and STAT-1 were used as internal controls. We showed that monocytes were probably the main producers of IL-12, and that NK and T cells produced similar amounts of IFN-gamma. NEMO and IRAK-4 were found to be important for IL-12 production and subsequent IFN-gamma production, while a lack of CD40L or HLA class II had no major impact on the IL-12/IFN-gamma axis. The stimulation of whole blood by live BCG thus triggers the IL-12/IFN-gamma axis by an IRAK-4- and NEMO-dependent, non-cognate interaction between monocytes, NK, and T lymphocytes.

Interferon-γ assays in the immunodiagnosis of tuberculosis: a systematic review

A major challenge in tuberculosis control is the diagnosis and treatment of latent tuberculosis infection. Until recently, there were no alternatives to the tuberculin skin test (TST) for diagnosing latent tuberculosis. However, an alternative has now emerged in the form of a new in-vitro test: the interferon-gamma assay. We did a systematic review to assess the performance of interferon-gamma assays in the immunodiagnosis of tuberculosis. By searching databases, contacting experts and test manufacturers, we identified 75 relevant studies. The results suggest that interferon-gamma assays that use Mycobacterium tuberculosis-specific region of difference 1 (RD1) antigens (such as early secretory antigenic target 6 and culture filtrate protein 10) may have advantages over the TST, in terms of higher specificity, better correlation with exposure to M tuberculosis, and less cross-reactivity due to BCG vaccination and non-tuberculous mycobacterial infection. However, interferon-gamma assays that use RD1 antigens in isolation may maximise specificity at the cost of sensitivity. Assays that use cocktails of RD1 antigens seem to overcome this problem, and such assays have the highest accuracy. RD1-based interferon-gamma assays can potentially identify those with latent tuberculosis who are at high risk for developing active disease, but this requires confirmation. There is inadequate evidence on the value of interferon-gamma assays in the management of immunocompromised individuals, children, patients with extrapulmonary or non-tuberculous mycobacterial disease, and populations in countries where tuberculosis is endemic. Current evidence suggests that interferon-gamma assays based on cocktails of RD1 antigens have the potential to become useful diagnostic tools. Whether this potential can be realised in practice remains to be confirmed in well designed, long-term studies.

Successful treatment of dermatomyositis and polymyositis with anti-tumor-necrosis-factor-alpha: preliminary observations

Tumor necrosis factor alpha neutralization seems a rational therapy for myositis because this proinflammatory cytokine has been implicated in the pathogenesis of this disorder. Until now, we have treated 2 patients with a chimeric anti-TNF-alpha monoclonal antibody (infliximab). Both patients demonstrated a marked and sustained subjective and objective improvement without the occurrence of any side effects. These preliminary results suggest that anti-TNF-alpha treatment with infliximab is a safe and rapidly effective therapy for myositis.

A model of human whole blood lymphokine release for in vitro and ex vivo use

Endotoxin (lipopolysaccharide, LPS) inducible cytokine release by human whole blood is increasingly used to model inflammatory responses in vitro, to detect the presence of pyrogenic contaminations as well as to monitor disease states or immunomodulatory treatments ex vivo. However, the LPS-stimulated blood model primarily allows the assessment of monocyte responses. Here, a whole blood model was established which allows assessment of lymphocyte responses. Four different superantigens, namely staphylococcal enterotoxin A and B (SEA, SEB), toxic shock syndrome toxin-1 (TSST-1) or streptococcal exotoxin A (SPEA) were tested with respect to the induction of lymphokine release. All superantigens were capable of inducing significant amounts of the lymphokines interferon-gamma (IFNgamma), interleukin 2 (IL-2), IL-4, IL-5, IL-13 and tumor necrosis factor beta (TNFbeta) after 72 h of incubation. Concentration-dependencies and kinetics were determined. Blood from 160 healthy donors was used to assess the variability of SEB-inducible lymphokine release. Interindividual differences were more pronounced compared to LPS-inducible monokine release. However, the individual response was maintained when blood from six donors was tested once a week for 8 weeks, suggesting that the individual response represents a donor characteristic. The model appears to be suitable for the evaluation of immunomodulatory agents in vitro as well as ex vivo.

Cytokine profiles using whole-blood assays can discriminate between tuberculosis patients and healthy endemic controls in a BCG-vaccinated population

Whole-blood assays (WB) provide a simple tool for assessing immune cytokine profiles which may be useful laboratory predictors of early disease, aiding the evaluation of new tuberculosis (TB) vaccines and offering insights into disease pathogenesis. Although BCG does not provide protection against pulmonary disease in TB endemic areas, it does modulate immune responses to mycobacterial antigens. It is important, therefore, to evaluate any new tool in an endemic setting in both BCG vaccinees and patients with tuberculosis. We have assessed the optimal conditions in terms of dose and kinetics of those cytokines which are released early (TNF-alpha, IL6 and TGF-beta, IL10) or (interferon [IFN]-gamma and IL5) in WB cultures stimulated with mitogens and mycobacterial antigens. Responses were studied in parallel in untreated TB patients and endemic control groups. Optimal responses to LPS (predominantly monocyte-derived) occurred on days 1-2, whereas for PHA (predominantly T-cell-derived), they were on days 3-5. Secreted Mycobacterium tuberculosis culture filtrate proteins (CFP) provided a stronger stimulus for monocyte-derived cytokines compared to PPD, but both antigens were comparable for induction of T-cell cytokines. Using unpaired Student's t-tests, pulmonary tuberculosis patients (P.TB; n=11), in response to CFP, showed higher monocyte-derived IL6 (p=0.023) and IL10 (p=0.042) compared to endemic controls (EC; n=13), and significantly suppressed T-cell-derived IFN-gamma (p=0.028) and IL5 (p=0.012) secretion but increased IL10 (p=0.047) on day 5, indicating that CFP is a strong stimulus for IL10 secretion in pulmonary TB patients. Extrapulmonary TB patients (E.TB; n=6) showed no elevation of early monocyte-derived cytokines to either PPD or CFP, but showed a marked suppression of the T-cell-derived cytokines IFN-gamma (PPD, p=0.015; CFP, p=0.05) and IL5 (PPD, p=0.05; CFP, p=0.015). Cytokine analysis in WB cultures is, therefore, able to discriminate between active tuberculosis infection and nondiseased healthy controls.

HEPC-based liposomes trigger cytokine release from peripheral blood cells: effects of liposomal size, dose and lipid composition

The immune response caused by liposome stimulation was studied by assessing the level of several cytokines released from human peripheral blood cells. Liposome stimulation resulted in the release of IL-6, IL-10, IL-1beta, TNF-alpha and IFN-gamma. The size of the liposomes affected the degree of the cytokine releases with larger sized liposomes causing higher levels of cytokine induction. In addition, it appears that the lipid composition of liposomes had no effect on the degree of cytokine release. The release of cytokines occurred even in the absence of serum, suggesting that serum proteins did not contribute to liposome stimulation in peripheral blood cells. The release of cytokines induced by liposome stimulation was inhibited by the presence of either protein kinase-C (PKC) or protein tyrosine kinase (PTK) inhibitor, but not by the presence of an endocytosis inhibitor. This indicates that signal transduction via PKC or PTK is necessary, in order for human peripheral blood cells to release cytokines (IL-6, IL-10, IL-1beta, TNF-alpha and IFN-gamma) as the result of liposome stimulation. These quantitative data on the release of cytokines by liposomal stimulation provide useful information for the development of rational drug delivery systems and the safety of cytokine induction via the use of liposomes.

Innate immunity to Mycobacterium tuberculosis

The different manifestations of infection with Mycobacterium tuberculosis reflect the balance between the bacillus and host defense mechanisms. Traditionally, protective immunity to tuberculosis has been ascribed to T-cell-mediated immunity, with CD4(+) T cells playing a crucial role. Recent immunological and genetic studies support the long-standing notion that innate immunity is also relevant in tuberculosis. In this review, emphasis is on these natural, innate host defense mechanisms, referring to experimental data (e.g., studies in gene knockout mice) and epidemiological, immunological, and genetic studies in human tuberculosis. The first step in the innate host defense is cellular uptake of M. tuberculosis, which involves different cellular receptors and humoral factors. Toll-like receptors seem to play a crucial role in immune recognition of M. tuberculosis, which is the next step. The subsequent inflammatory response is regulated by production of pro- and anti-inflammatory cytokines and chemokines. Different natural effector mechanisms for killing of M. tuberculosis have now been identified. Finally, the innate host response is necessary for induction of adaptive immunity to M. tuberculosis. These basic mechanisms augment our understanding of disease pathogenesis and clinical course and will be of help in designing adjunctive treatment strategies.

Effect of Mycobacterium bovis BCG vaccination on interleukin-1 beta and RANTES mRNA expression in guinea pig cells exposed to attenuated and virulent mycobacteria

The effect of Mycobacterium bovis BCG vaccination on interleukin-1 beta (IL-1 beta) or regulated-upon-activation, normally T-cell-expressed and -secreted chemokine (RANTES) mRNA expression in guinea pig spleen cells stimulated with concanavalin A, lipopolysaccharide (LPS), phorbol myristate acetate (PMA) plus ionomycin, or purified protein derivative (PPD) was studied in vitro. Similarly, peritoneal exudate cell-derived macrophages from naïve and BCG-vaccinated guinea pigs were infected with M. bovis BCG, Mycobacterium avium, the attenuated Mycobacterium tuberculosis H37Ra strain, or virulent strains H37Rv and Erdman of M. tuberculosis. Total RNA was subjected to Northern blot analysis using probes generated from guinea pig IL-1 beta or RANTES cDNA. Although IL-1 beta and RANTES mRNA could be detected in the spleen cells from naïve animals stimulated with LPS or PMA plus ionomycin, the levels were significantly enhanced after BCG vaccination. mRNA expression was also elevated in macrophages infected with live mycobacteria after BCG vaccination. However, macrophages infected with the virulent H37Rv strain of M. tuberculosis showed 75 to 90% reductions in IL-1 beta expression and 25 to 60% reductions in RANTES mRNA expression compared with macrophages infected with the attenuated H37Ra strain. The IL-1 beta mRNA levels peaked as soon as 1 h after PPD stimulation and 4 h after M. tuberculosis H37Rv infection of macrophages. In contrast, RANTES mRNA expression was delayed until 48 h after infection. These results indicate that molecular mediators produced in response to various stimuli associated with protective immunity against mycobacteria are upregulated after BCG vaccination; however, a significantly weaker response was observed with virulent M. tuberculosis. These initial studies indicate that BCG vaccination has a positive effect on IL-1 beta and RANTES mRNA expression by host cells in a highly relevant animal tuberculosis model.

Decreased plasma leptin concentrations in tuberculosis patients are associated with wasting and inflammation

Tuberculosis patients often suffer from severe weight loss, which is considered to be immunosuppressive and a major determinant of severity and outcome of disease. Because leptin is involved in weight regulation and cellular immunity, its possible role in tuberculosis-associated wasting was investigated. In an urban clinic in Indonesia, plasma leptin concentrations, indicators of adipocyte mass, appetite, C-reactive protein (CRP), tuberculin reactivity, and cytokine response were measured in tuberculosis patients and healthy controls. Plasma leptin concentrations were lower in patients than in controls (615 vs. 2,550 ng/liter; P < 0.001). Multivariate regression analysis showed that body fat mass and inflammation were two independent factors determining plasma leptin concentrations; there was a positive correlation between fat and leptin, whereas, unexpectedly, leptin was inversely associated with CRP and tumor necrosis factor-alpha production. Concentrations of both CRP and leptin were independently associated with loss of appetite. Our results do not support the concept that weight loss in tuberculosis is caused by enhanced production of leptin. Rather, loss of body fat leads to low plasma leptin concentrations, and prolonged inflammation may further suppress leptin production. Because leptin is important for cell-mediated immunity, low leptin production during active tuberculosis may contribute to increased disease severity, especially in cachectic patients.

A comparison of cellular and humoral immune responses to trichuroid derived antigens in human trichuriasis

Individuals, residing in a region highly endemic for Trichuris trichiura, were examined for cytokine and proliferative responses to T. trichiura worm homogenate (TtAg), T. trichiura excretory/secretory products (TtES) and the equivalent antigenic preparations from the murine whipworm, Trichuris muris. Serum antibody levels against TtAg, T. muris worm homogenate and T. muris ES products were also studied. Measurable levels of immunoglobulin (Ig)G1, IgG4, IgA and IgE against T. muris antigens were detected, indicating a degree of conservation of epitopes between antigens derived from both species. Although levels of interleukin (IL)-4, IL-10, IL-13, tumour necrosis factor (TNF)-alpha and proliferative responses produced were comparable between homogenate antigens of either species and ES antigens of either species, a markedly different cellular response was observed in cultures stimulated with homogenate antigens compared to ES antigens. ES antigens preferentially induced IL-10 (P > 0.001) and TNF-alpha (P > 0.001) production, whereas levels of IL-4 (P > 0.001), IL-13 (P > 0.001) and proliferative responses (P > 0.001) were greater in cultures stimulated with whole worm extracts. Our findings suggest that T. muris preparations could be used as an alternative to T. trichiura proteins as a source of antigens in ex vivo cultures and that ES products stimulate a distinct immune response compared to somatic antigens.

Tuberculin skin testing compared with T-cell responses to Mycobacterium tuberculosis-specific and nonspecific antigens for detection of latent infection in persons with recent tuberculosis contact

The tuberculin skin test (TST) is used for the identification of latent tuberculosis (TB) infection (LTBI) but lacks specificity in Mycobacterium bovis BCG-vaccinated individuals, who constitute an increasing proportion of TB patients and their contacts from regions where TB is endemic. In previous studies, T-cell responses to ESAT-6 and CFP-10, M. tuberculosis-specific antigens that are absent from BCG, were sensitive and specific for detection of active TB. We studied 44 close contacts of a patient with smear-positive pulmonary TB and compared the standard screening procedure for LTBI by TST or chest radiographs with T-cell responses to M. tuberculosis-specific and nonspecific antigens. Peripheral blood mononuclear cells were cocultured with ESAT-6, CFP-10, TB10.4 (each as recombinant antigen and as a mixture of overlapping synthetic peptides), M. tuberculosis sonicate, purified protein derivative (PPD), and short-term culture filtrate, using gamma interferon production as the response measure. LTBI screening was by TST in 36 participants and by chest radiographs in 8 persons. Nineteen contacts were categorized as TST negative, 12 were categorized as TST positive, and 5 had indeterminate TST results. Recombinant antigens and peptide mixtures gave similar results. Responses to TB10.4 were neither sensitive nor specific for LTBI. T-cell responses to ESAT-6 and CFP-10 were less sensitive for detection of LTBI than those to PPD (67 versus 100%) but considerably more specific (100 versus 72%). The specificity of the TST or in vitro responses to PPD will be even less when the proportion of BCG-vaccinated persons among TB contacts evaluated for LTBI increases.

Apolipoprotein A-I inhibits the production of interleukin-1beta and tumor necrosis factor-alpha by blocking contact-mediated activation of monocytes by T lymphocytes

Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), essential components in the pathogenesis of immunoinflammatory diseases, are strongly induced in monocytes by direct contact with stimulated T lymphocytes. This study demonstrates that adult human serum (HS) but not fetal calf or cord blood serum displays inhibitory activity toward the contact-mediated activation of monocytes by stimulated T cells, decreasing the production of both TNF-alpha and IL-1beta. Fractionation of HS and N-terminal microsequencing as well as electroelution of material subjected to preparative electrophoresis revealed that apolipoprotein A-I (apo A-I), a "negative" acute-phase protein, was the inhibitory factor. Functional assays and flow cytometry analyses show that high-density lipoprotein (HDL)-associated apo A-I inhibits contact-mediated activation of monocytes by binding to stimulated T cells, thus inhibiting TNF-alpha and IL-1beta production at both protein and messenger RNA levels. Furthermore, apo A-I inhibits monocyte inflammatory functions in peripheral blood mononuclear cells activated by either specific antigens or lectins without affecting cell proliferation. These results demonstrate a new anti-inflammatory activity of HDL-associated apo A-I that might have modulating functions in nonseptic conditions. Therefore, because HDL has been shown to bind and neutralize lipopolysaccharide, HDL appears to play an important part in modulating both acute and chronic inflammation. The novel anti-inflammatory function of apo A-I reported here might lead to new therapeutic approaches in inflammatory diseases such as rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, and atherosclerosis.

Persistent symptoms in former UNTAC soldiers are not associated with shifted cytokine balance

BACKGROUND

The pathogenesis of post-combat syndromes, such as Gulf War syndrome, is poorly understood. Recently, it has been postulated that the symptoms of veterans with such syndromes are due to a disturbed cytokine balance shifted towards a T-helper (Th) 2 profile. We investigated this hypothesis in 21 symptomatic former UNTAC soldiers and compared their results with those obtained in 21 healthy former UNTAC soldiers matched for age, sex and military force.

DESIGN

The numbers of intracellular interleukin 4 (IL-4) and interferon gamma- (IFN-gamma) producing CD4+ and CD8+ T lymphocytes (CD3+) were determined after in vitro stimulation with phorbol myristate acetate and calcium ionophore in the presence of brefeldin to block secretion of induced cytokines. Circulating concentrations and lipopolysaccharide- (LPS) or phytohaemagglutinin- (PHA) stimulated whole-blood production of the proinflammatory cytokines IL-1beta, IL-1ra, tumour necrosis factor alpha (TNF-alpha) and IL-10 and IFN-gamma were measured.

RESULTS

The numbers of CD4+ and CD8+ T lymphocytes positive for IL-4 or IFN-gamma production were not significantly different in patients and control subjects. After stimulation with LPS or PHA, the in vivo circulating concentration and concentration of IL-10 and IFN-gamma were also similar.

CONCLUSIONS

The present study demonstrates that there is no shift in cytokine balance towards a Th2 profile in former UNTAC soldiers with symptoms similar to those of the Gulf War syndrome.