Direct stimulation of cytokines (IL-1 beta, TNF-alpha, IL-6, IL-2, IFN-gamma and GM-CSF) in whole blood. I. Comparison with isolated PBMC stimulation

Immunoregulatory effects of adenosine 5'-triphosphate on cytokine release from stimulated whole blood

In vitro studies suggest that extracellular nucleotides and nucleosides may be important regulators of inflammatory and immune responses. Most studies with adenosine 5'-triphosphate (ATP) have been performed in cell lines, which are remote from the human situation. The purpose of the present study was to determine the effects of ATP on TNF-alpha, IL-6 and IL-10 release in stimulated whole blood. Blood samples were drawn from healthy volunteers and incubated with ATP and lipopolysaccharide (LPS) + phytohemagglutinin (PHA) for 24 h. Contrary to expectations, ATP at 100 microM and 300 microM induced a reduction in TNF-alpha secretion by 32+/-8% (mean +/- SEM) and 65+/-4%, respectively. Furthermore, these ATP concentrations induced an increase in IL-10 secretion by 48+/-5% and 62+/-7% in whole blood. The ATP analogue adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S) and adenosine 5'-diphosphate (ADP) also inhibited TNF-alpha release, but only ADP showed a stimulatory effect on IL-10. Co-treatment with adenosine deaminase did not reverse the ATP effect on TNF-alpha and IL-10. These results show, for the first time, that ATP inhibits the inflammatory response in stimulated whole blood as indicated by inhibition of TNF-alpha and stimulation of IL-10 release and that this effect is predominantly mediated by ATP and not by adenosine.

Reduced Release of Intact and Cleaved Urokinase Receptor in Stimulated Whole-Blood Cultures from Human Immunodeficiency Virus-1-Infected Patients

The blood levels of the soluble forms of the urokinase receptor (suPAR) are increased in human immunodeficiency virus (HIV)-1-infected patients. This study investigated whether the release of urokinase-type plasminogen activator receptor (uPAR) in whole-blood cultures was affected by HIV infection. The release of different uPAR forms in whole-blood cultures incubated 24 h with or without phytohemagglutinin and lipopolysaccharide was analysed in 47 HIV patients and 19 controls. suPAR was measured by enzyme-linked immunosorbent assay (ELISA) (bulk-suPAR) and three different time-resolved fluorescence immunoassays measuring three-domain suPAR [suPAR(I-III)], three- and two-domain suPAR [suPAR(I-III) + suPAR(II-III)] and one-domain suPAR [suPAR(I)]. The uPAR release was correlated to leucocyte subpopulations and plasma levels of suPAR. The stimulated net whole-blood culture release of bulk-uPAR, uPAR(I-III), uPAR(II-III) and uPAR(I) was reduced in HIV patients (all P < 0.01), whereas the spontaneous bulk-uPAR and uPAR(I-III) release was increased in HIV patients (both P < 0.05). The stimulated uPAR release in whole-blood cultures correlated well to leucocytes and circulating suPAR levels in controls, whereas the correlation was weaker to leucocytes and nonexisting to circulating suPAR levels in HIV patients. These findings demonstrate that HIV infection affects stimulated and spontaneous uPAR release in whole-blood cultures. Given that high blood levels of suPAR in HIV patients are linked to immune activation, the perturbations in uPAR release in whole-blood cultures from HIV patients may also reflect immune activation.

Bupivacaine???s Action on the Carrageenan-Induced Inflammatory Response in Mice: Cytokine Production by Leukocytes After Ex-Vivo Stimulation

We aimed to study the effect of bupivacaine on the systemic response elicited by intraplantar injection of carrageenan. To that purpose, we studied the effects of carrageenan, bupivacaine, or both on the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-10 by whole blood cultured in the presence of lipopolysaccharide (LPS) and of heat-killed Staphylococcus Aureus Cowan (SAC). Mice received a hindpaw injection of carrageenan with or without encapsulated IM bupivacaine given contralaterally. Whole blood was sampled 15 h later and cultured for 24 h with LPS or SAC. The amounts of TNF-alpha, IL-1beta, and IL-10 in the supernatants were measured. In the presence of LPS or SAC, proinflammatory cytokine (TNF-alpha and IL-1beta) production was increased after carrageenan. Bupivacaine prevented this inflammatory response: 992 +/- 102 versus 2146 +/- 338 versus 919 +/- 116 pg/mL for TNF-alpha (bupivacaine + carrageenan versus carrageenan versus control after LPS stimulation). This effect of bupivacaine was less after SAC stimulation. Moreover, IL-10 was not involved in the inhibition of proinflammatory cytokine production observed after treatment by bupivacaine alone. These experiments show that carrageenan-induced hindpaw inflammation modifies the blood cell reactivity to LPS and SAC and that bupivacaine regulates the systemic response elicited by carrageenan. Furthermore, IL-10 does not seem to be a factor of the antiinflammatory response induced by bupivacaine. The precise mechanism underlying this effect of bupivacaine remains to be clarified.

Stress-induced versus preovulatory and pregnancy hormonal levels in modulating cytokine production following whole blood stimulation

Estradiol, progesterone, prolactin and cortisol concentrations are substantially increased during pregnancy. Also, cortisol and prolactin levels are elevated during stress. In the present study, we exposed peripheral blood to estradiol, progesterone, prolactin and cortisol alone or in combination for 24 h before stimulation with T-dependent (phytohemagglutinin, PHA) and independent activators (lipopolysaccharide, LPS) to study their immunomodulatory role in interleukin-12 (IL-12), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), and IL-10 production in a whole blood model. This should be similar to in vivo exposure conditions such as long-term stress, preovulatory or pregnancy periods. The present study showed that the stress-induced and preovulatory levels of prolactin and estradiol, respectively, increased the production of IFN-gamma and IL-12 levels (and IL-10 in the case of estradiol) in PHA + LPS-stimulated whole blood, and inhibited a hydrocortisone (100 nmol/l) suppressive effect on IFN-gamma, IL-12 and IL-10 productions. In LPS-stimulated whole blood, however, prolactin enhanced only IL-10 production levels in a non-concentration-dependent manner. Higher prolactin levels as in pregnancy did not modulate any of the cytokines, but pregnancy estradiol concentrations only induced higher IL-10 levels in PHA + LPS-stimulated whole blood. All progesterone levels tested revealed no effect on any of the cytokines following whole blood stimulation. Our results indicate that (1) a long exposure time of prolactin and estradiol to whole blood modulates the production of cytokines in a concentration- and stimulus-dependent manner; (2) stress-induced levels of prolactin and preovulatory estradiol concentrations can regulate cortisol-induced cytokine suppression, and (3) even though the cytokine pattern is different, pregnancy estradiol and cortisol levels decreased the IFN-gamma/IL-10 ratio, thereby keeping the anti-inflammatory IL-10 levels favored during pregnancy, which could be useful in regulating inflammatory-mediated autoimmune diseases.

Human endometrial leukemia inhibitory factor and interleukin-6: control of secretion by transforming growth factor-beta-related members

OBJECTIVE(S)

The implantation process is closely linked to the fundamental question of the tolerance of the maternal immune system. The main objective of this study was to investigate whether different members of the transforming growth factor-beta (TGF-beta) superfamily could intervene in the first steps of embryo implantation by modulating the secretion of proimplantatory leukemia inhibitory factor (LIF) and in the tolerance of the fetal graft by regulating proinflammatory interleukin (IL)-6 secretion by human endometrial epithelium (EEC) in vitro.

METHODS

EEC were isolated from biopsies collected from 16 informed and consenting fertile women and were cultured for 72 h. Cytokine measurements (LIF and IL-6) were realized by ELISA.

RESULTS

TGF-beta(1) (from 10(-12) to 10(-8)M), -beta(2), -beta(3) and activin A (10(-10) and 10(-8)M) increased LIF secretion by EEC cultures. Inhibin B (10(-10) and 10(-8)M) did not stimulate LIF production by human EEC. Contrastingly, TGF-beta(1) (from 10(-12) to 10(-8)M), -beta(2), -beta(3) and activin A (10(-10) and 10(-8)M) reduced IL-6 release by the same cells. Activin A at 10(-8) M also significantly reduced the stimulating effect of IL-1beta (10(-9)M) which is known to stimulate LIF production by EEC. Only the highest concentration of inhibin B (10(-8)M) reduced IL-6 secretion by EEC, but did not modulate IL-1beta-induced stimulation of IL-6 secretion.

CONCLUSION(S)

Besides their role in the control of the process of implantation and in the induction of embryonic mesoderm, different members of the TGF-beta superfamily may also contribute in the reproductive process by enhancing endometrial proimplantatory LIF secretion and reducing proinflammatory IL-6 release by EEC.

In vitro modulation of inflammatory cytokine production by three lipid emulsions with different fatty acid compositions

BACKGROUND AND AIMS

Studies have suggested that 100% long-chain triacylglycerols (LCTs) lipid emulsions exhibit immunosuppressive effects, sometimes suspected to favor infectious complications in patients receiving parenteral nutrition. Newer emulsions, in particular olive oil-based emulsions, seem to have lesser immunosuppressive effects. We studied the in vitro effect of 100% LCTs (Intralipide), 50% LCTs-50% medium chain triacylglycerols (Medialipide), and 80% olive oil-based lipid emulsions (ClinOleic) on inflammatory cytokines production by peripheral blood mononuclear cells (PBMCs).

METHODS

PBMCs separated by gradient centrifugation, or whole blood, were incubated with 0.001%, 0.01%, 0.1% and 1% of the three tested lipid emulsions during 24h in the presence or absence of activation by lipopolysaccharide and phytohemagglutinin. Then, supernatants were collected and cytokines measured (ELISA).

RESULTS

The three lipid emulsions reduced basal TNF-alpha and IL-1beta production in PBMCs and whole blood cultures. However, ClinOleic was significantly less powerful in TNF-alpha and IL-1beta inhibition by isolated PBMCs than Intralipide and Medialipide. Basal TNF-alpha production was equally inhibited by the three emulsions in whole blood, but IL-1beta production was not significantly modified by ClinOleic. Interleukin-6 and -8 were not affected. After cell activation, lipid emulsions exhibit no effect on cytokines production.

CONCLUSION

ClinOleic induces a significantly lower in vitro inhibition of TNF-alpha and IL-1beta production by PBMCs than 100% LCTs or 50% LCTs-50% MCTs emulsions, and therefore might be more immune neutral. These effects vary from one subject to another, and disappeared after cell activation. Therefore, caution must be taken before extrapolation in vivo. Provided information should be taken into account for future design of clinical trials studying the immune modulating properties of lipid emulsions.

Enhanced glucocorticoid sensitivity of cytokine release from circulating leukocytes stimulated with lipopolysaccharide in healthy male smokers

Smoking is a strong cardiovascular risk factor that promotes inflammation. The source of elevated pro-inflammatory cytokines in the circulation of smokers is not fully understood. We investigated the release of pro-inflammatory cytokines from circulating leukocytes stimulated with lipopolysaccharide (LPS) and its inhibition by glucocorticoids in smokers and non-smokers. Ninety-three middle-aged apparently healthy men were categorized as smokers (> 10 cigarettes/day; n = 41) or life-long non-smokers (n = 52). Peripheral cortisol was assessed from overnight urine. C-reactive protein (CRP) and tumor necrosis factor (TNF)-alpha were measured in plasma. LPS-stimulated interleukin (IL)-6 and TNF-alpha release from harvested circulating leukocytes were assessed using an in vitro whole blood assay with and without co-incubation of increasing concentrations of either dexamethasone or hydrocortisone. Glucocorticoid sensitivity was defined as the concentration of glucocorticoids required that inhibits LPS-stimulated cytokine release by 50%. Smokers had higher CRP levels (p = .005) and a trend for higher basal TNF-alpha levels (p < .07), and they also showed lower IL-6 and TNF-alpha release after LPS-stimulation than non-smokers (p's < .001). While peripheral cortisol concentration showed no significant group difference, inhibition of LPS-stimulated leukocyte IL-6 and TNF-alpha release by either glucocorticoid was enhanced in smokers as compared to non-smokers (p's < .022). The finding suggests that, in spite of a low-grade systemic inflammation, smokers have decreased LPS-stimulated cytokine release from circulating leukocytes and greater glucocorticoid sensitivity of this cytokine release than non-smokers. Circulating leukocytes unlikely contribute to the elevated pro-inflammatory cytokine levels in the blood of smokers.

Monocyte proinflammatory cytokine release is higher and glucocorticoid sensitivity is lower in middle aged men than in women independent of cardiovascular risk factors

OBJECTIVE

To investigate whether stimulated monocyte cytokine release and its inhibition by glucocorticoids differs between men and women.

DESIGN

In vitro monocyte interleukin 6 (IL-6) and tumour necrosis factor alpha (TNFalpha) release after lipopolysaccharide stimulation were assessed with and without co-incubation with increasing doses of dexamethasone and hydrocortisone separately. Glucocorticoid sensitivity was defined as the amount of a particular glucocorticoid required to inhibit lipopolysaccharide stimulated monocyte cytokine release by 50%. The established cardiovascular risk factors of age, body mass index, number of cigarettes smoked daily, low density cholesterol to high density cholesterol ratio, systolic and diastolic blood pressure, and haemoglobin A1c were used as covariates.

SETTING

Aircraft manufacturing plant in southern Germany.

PATIENTS

269 middle aged male and 36 middle aged female employees.

RESULTS

Release of monocyte IL-6 and TNFalpha (each p = 0.001) was higher in samples from men than in those from women. Inhibition of lipopolysaccharide stimulated IL-6 and TNFalpha release by either glucocorticoid was less pronounced in samples from men than in those from women (IL-6: dexamethasone p = 0.033, hydrocortisone p = 0.029; TNFalpha: dexamethasone p < 0.001, hydrocortisone p = 0.089).

CONCLUSIONS

The finding suggests that proinflammatory activity of circulating monocytes is higher in men than in women independent of cardiovascular risk factors, thereby providing one explanation for the relatively greater coronary risk in men.

Immune monitoring of patients with septic shock by measurement of intraleukocyte cytokines

OBJECTIVE

To assess the immune competence of patients presenting with septic shock by measuring on-line the production of intracellular cytokines by circulating leukocytes.

DESIGN AND SETTING

Prospective study in a 18-bed medical intensive care unit of a university hospital.

PATIENTS AND PARTICIPANTS

21 patients with septic shock, and 11 volunteers.

INTERVENTIONS

Single-step isolation of leukocytes from whole blood obtained within the first 24 h after admission. Leukocytes were fixed immediately or after treatment with lipopolysaccharide (LPS) and/or heterologous plasma.

MEASUREMENTS AND RESULTS

Leukocytes were permeabilized, and the intracellular cytokine expression of TNF-alpha and IL-10 was quantified by immunostaining and flow cytometry. LPS treatment significantly increased monocyte intracellular cytokine TNF-alpha and IL-10 as well as lymphocyte intracellular cytokine IL-10 in normal leukocytes. Septic monocytes and granulocytes had nonstimulated intracellular cytokine TNF-alpha concentrations lower than those measured in volunteers and were severely hyporesponsive to LPS. These phenotypic changes were correlated with disease severity and could be reproduced by treatment of normal leukocytes with plasma from patients with septic shock.

CONCLUSIONS

Intracellular cytokine staining is a simple and rapid method to assess in situ and on-line the inflammatory balance and responsiveness of leukocyte subpopulations and could therefore represent a useful monitoring tool to assess the immune competence of critically ill patients. This study identifies the cellular source of cytokines in whole blood and confirms prior reports showing that septic phagocytes are characterized by a predominant anti-inflammatory phenotype, with hyporesponsiveness to LPS, depending on a plasma deactivation factor.

Differential maturation of the innate immune response in human fetuses

Newborns and especially preterm infants show a unique susceptibility to severe bacterial infections that cause significant morbidity and mortality. As very few data are available on innate immune functions in human fetuses, we conducted a comprehensive study to investigate the expression of several adhesion molecules essentially involved in migration (CD11a, CD11b, CD11c, CD18, and CD62L). Furthermore, phagocytic activity, generation of respiratory burst products, and production of several proinflammatory cytokines were assessed. Various functions of the fetal innate immune system were demonstrated to be essentially different from those observed in term neonates or adults. Expression of several surface markers was significantly diminished on fetal granulocytes. Furthermore, a significantly reduced phagocytic activity of fetal granulocytes and monocytes was found, contrasted by an enhanced generation of reactive oxygen products. In addition, we demonstrate that significant numbers of fetal monocytes are capable of the production of proinflammatory cytokines in response to stimulation. However, the pattern of cytokine production is different from the more mature individuals: the number of IL-6- and tumor necrosis factor-alpha-positive monocytes were significantly diminished, whereas more IL-8-producing monocytes were found compared with adults. The results of our study add significantly to our understanding of the maturation and impairment of the innate immune response.

Reduced glucocorticoid sensitivity of monocyte interleukin-6 release in male employees with high plasma levels of tumor necrosis factor-alpha

Cytokine production by monocytes plays a key role in atherosclerosis. In vitro, preincubation of whole blood with tumor necrosis factor (TNF)-alpha regulates interleukin (IL)-6 release from monocytes stimulated with lipopolysaccharide (LPS). We investigated whether plasma levels of TNF-alpha would also relate to LPS-stimulated monocyte IL-6 production and the inhibitory effect of a glucocorticoid on this process. 224 middle-aged men were assigned to three groups according to tertiles of plasma levels of TNF-alpha. Subjects in the highest tertile (high TNF-alpha, n = 75) were compared to those in the lowest (low TNF-alpha, n = 74) and medium tertile (medium TNF-alpha, n = 75), respectively. In vitro monocyte IL-6 release following lipopolysaccharide (LPS)-stimulation was assessed with and without coincubation with incremental doses of dexamethasone. Monocyte glucocorticoid sensitivity was defined as the dexamethasone concentration inhibiting IL-6 release by 50%. Subjects with high TNF-alpha showed more IL-6 release after LPS-stimulation than those with low TNF-alpha (p =.011). Monocyte glucocorticoid sensitivity was lower in subjects with high levels of TNF-alpha than in subjects with low (p =.014) and with medium (p =.044) levels of TNF-alpha. Results held significance when a set of classic cardiovascular risk factors was controlled for. Our findings suggest that elevated plasma levels of TNF-alpha might enhance LPS-stimulated IL-6 release from circulating monocytes. Such a mechanism might contribute to exaggerated monocyte cytokine release in vivo to any LPS-like danger signal such as related to an infection or cellular stress thereby promoting atherosclerosis.

Uninfected erythrocytes inhibit Plasmodium falciparum–induced cellular immune responses in whole-blood assays

Whole-blood assays (WBAs) have been successfully used as a simple tool for immuno-epidemiological field studies evaluating cellular immune responses to mycobacterial and viral antigens. Rather unexpectedly, we found very poor cytokine responses to malaria antigens in WBAs in 2 immuno-epidemiological studies carried out in malaria endemic populations in Africa. We have therefore conducted a detailed comparison of cellular immune responses to live (intact) and lysed malaria-infected erythrocytes in WBAs and in peripheral blood mononuclear cell (PBMC) cultures. We observed profound inhibition of both proliferative and interferon-γ responses to malarial antigens in WBAs as compared with PBMC cultures. This inhibition was seen only for malaria antigens and could not be overcome by increasing either antigen concentration or responder cell numbers. Inhibition was mediated by intact erythrocytes and occurred early in the culture period, suggesting that failure of antigen uptake might underlie the lack of T-cell responses. In support of this hypothesis, we have shown that intact uninfected erythrocytes specifically inhibit phagocytosis of infected red blood cells by peripheral blood monocytes. We propose that specific biochemical interactions with uninfected erythrocytes inhibit the phagocytosis of malaria-infected erythrocytes and that this may impede T-cell recognition in vivo. (Blood. 2004; 103:3084-3092)

TNF-α promoter, Nod2 and toll-like receptor-4 polymorphisms and the in vivo and ex vivo response to endotoxin

Humans exhibit substantial inter-individual differences in TNF-alpha production upon endotoxin stimulation. To determine to what extent the lipopolysaccharide-induced TNF-alpha production capacity in vivo and ex vivo is determined by polymorphisms in toll-like receptor-4 (TLR4), the TNF-alpha promoter region and Nod2, we screened for two TLR4 polymorphisms, a Nod2 polymorphism and the TNF-alpha promoter polymorphisms. We measured the perioperative endotoxemia and TNF-alpha production and the TNF-alpha production capacity of each patient in a whole-blood stimulation assay using blood drawn before anesthesia, using various LPS concentrations, in patients undergoing elective cardiac surgery. This operation represents a major surgical trauma associated with ischemia-reperfusion injury and triggers an endotoxemia and profound inflammatory response. In vivo TNF-alpha production was positively correlated with the level of endotoxemia after aortic declamping; thus TNF-alpha levels were higher in patients having endotoxemia compared to patients without endotoxemia. This correlation was observed in patients with any of the genotypes studied, and did not differ between the various genotypes. In vivo TNF-alpha levels correlated best with those ex vivo after stimulation with 1000 ng/mL LPS, and the estimated maximal TNF-alpha release capacity. Subjects with the wild-type TLR4 gene had similar levels of TNF-alpha upon LPS stimulation ex vivo as compared with patients carrying Asp299Gly and/or the Thr399Ile TLR4 polymorphism. Our results indicate that polymorphisms in the TLR4 receptor, Nod2 and TNF-alpha promoter region are not strongly associated with in vivo and ex vivo TNF-alpha production capacity upon endotoxin stimulation. This suggests that in this model of natural LPS release, the variation between individuals in TNF-alpha release can only modestly be determined by genetic background (TNF-alpha promoter, Nod2 and TLR4) of the individual.

Whole-blood cultures from renal-transplant patients stimulated ex vivo show that the effects of cyclosporine on lymphocyte proliferation are related to P-glycoprotein expression

BACKGROUND

Cyclosporine (CsA) is a substrate for the MDR-1 gene product P-glycoprotein (P-gp). CsA efficacy may be modulated by lymphocyte P-gp expression levels. In this study, CsA inhibition of lymphocyte proliferation in whole-blood cultures ex vivo has been related to (1) lymphocyte P-gp expression and (2) the C3435T polymorphism in the MDR-1 gene, which has been reported to alter P-gp function.

METHODS

In 30 renal-transplant recipients taking CsA monotherapy, P-gp expression was measured by flow cytometry. Whole-blood samples were stimulated with purified protein derivative (PPD) and phytohemagglutinin (PHA). CsA resistance ex vivo was defined as less than 10% reduction in proliferation with either PPD or PHA at 2 hours compared with 0 hours.

RESULTS

CsA resistance was associated with greater P-gp expression using either PPD (median expression, resistant 1.89 vs. sensitive 0.96, P =0.02) or PHA (1.66 vs. 0.96, respectively, P =0.02). Whole-blood CsA levels in resistant and sensitive patients were similar. The C3435T polymorphism did not affect inhibition of proliferation by CsA (P >0.05 for all between genotype group comparisons).

CONCLUSIONS

Our results indicate that lymphocyte P-gp expression determines the degree of inhibition of proliferation by CsA ex vivo; whether this also affects CsA effectiveness in vivo and therefore graft survival requires further study.

Stimulatory effect of antidepressants on the production of IL-6

A body of evidence indicates that the therapeutic activity of antidepressants is connected with their modulatory effect on the inflammatory response system and cell-mediated immunity. The present study was carried out to examine the effects of antidepressant agents, such as imipramne, venlafaxine, l-5-hydroxytryptophan, fluoxetine and a combination of l-5-hydroxytryptophan and fluoxetine, on the production of the pleotrophic cytokines TNF-alpha and IL-6. Diluted whole blood from fluoxetine-treated patients with treatment-resistant depression (TRD) (mean age: 50.6+/-3.9 years), age-matched healthy controls (mean age: 51.6+/-1.7 years) and younger healthy volunteers (mean age: 35.4+/-1.7 years) was stimulated with phytohemagglutinin (PHA) and lipopolysaccharide (LPS) for 48 h with or without incubation with the antidepressants at 10(-6) and 10(-5) M. The major findings of this study are: (1). imipramine and venlafaxine (at the higher concentration), 5-HTP (at lower and higher concentrations) and a combination of 5-HTP and fluoxetine (both at the lower concentration) increased the production of IL-6; (2). all drugs used did not affect TNF-alpha production. IL-6 production was significantly higher in depressed patients than in age-matched volunteers, whereas TNF-alpha production was significantly higher in older volunteers than in younger ones. We speculate that the therapeutic activity of these antidepressants is at least partly connected with their effect on the cytokine network and IL-6 production.

Are the cellular immune responses of children and adults with Schistosoma mansoni infection intrinsically different? Cytokines produced ex vivo in response to antigens and mitogens

In recently exposed communities, intensity of schistosomiasis infection increases as children age and then drops again in adulthood, indicating that host maturity is an important aspect of resistance to schistosomiasis. We investigated whether the cellular immune response to the parasite was correlated with age in subjects with similar daily patterns of exposure, current intensities of infection and number of years of exposure. The cellular immune response of subjects with either 'low' (under 200 eggs per gram (EPG)) or 'high' (over 400 EPG) intensities of infection was investigated, in a recently established focus where subjects had similar histories of exposure and number of years of experience with Schistosoma mansoni. Subject's whole blood was cultured with adult worm antigen (AWA), a mixture of phytohaemagglutinin (PHA) and lipopolysaccharide (LPS), or left unstimulated, and culture supernatants were tested for IL-4, IL-5, IL-10 and IFN-gamma. Children and adults tended to respond differently to schistosome antigen. The most statistically significant illustration of this was the negative correlation between age and IL-5 produced by samples from people with low intensities of infection cultured with AWA (P < 0.003, P < 0.05 after Bonferroni correction). IL-10 produced by samples cultured with PHA and LPS was also notably lower in children than in adults, although not formally significant after Bonferroni correction. This indicates that it is possible for age, independently of intensity of infection or experience with the parasite, to influence the immune response to schistosomiasis.

Seasonal variation in whole blood cytokine production after LPS stimulation in normal individuals

We examined seasonal differences in whole blood cytokine production after endotoxin (LPS) stimulation in 17 healthy individuals from an urban area having normal sleep/wakefulness pattern. We used 500 pg/ml of LPS for incubation period of 4 h to stimulate 100 microl of whole blood of the same subjects in June, September, February, and March. We found no differences in the circulating total WBCs and differentials including monocytes between different seasons. We found during September (autumn) a reduced pro-inflammatory cytokine production in terms of TNF-alpha and IL-6 production compared to the other seasons. We also found a reduced anti-inflammatory cytokine production in June (summer) and September (autumn) in terms of IL-10, TNF-RI and TNF-RII compared to February (winter) and March (spring). Our results suggest that in early summer there is a predominating pro-inflammatory cytokine response which is counterbalanced early in autumn. These results may have significant implications in the determination of reference values, in exploration of immune response and inflammatory disease prevalence between different seasons, in determining LPS tolerance (immunoparalysis) and planning clinical trials and immunomodulary therapies. However, the effect of dark/light exposure differences on the circadian periodicity in the responsiveness of immune cells during different seasons should be further investigated.

Toll-like receptor 4 and CD14 mRNA expression are lower in resistive exercise-trained elderly women

The purpose of this study was to examine the influence of resistive exercise training and hormone status on mRNA expression of toll-like receptor 4 (TLR4), CD14, IL-1beta, IL-6, and TNF-alpha. Resistive exercise-trained women on "traditional" hormone replacements [hormone replacement therapy (HRT), n = 9], not taking hormones (NHR, n = 6), or taking medications known to influence bone (MIB, n = 7) were compared with untrained subjects not taking supplemental hormones (Con, n = 6). Blood was taken from trained subjects before, immediately after, and 2 h after resistive exercise (same time points for resting Con). TLR4 mRNA expression (RT-PCR) was not different among groups or across time but was significantly (P = 0.044) lower (1.9-fold) when trained groups were collapsed and compared with Con. There was also a significant group effect (P < 0.0001) for TLR4 mRNA when expressed per monocyte. CD14 expression was significantly (P = 0.006) lower (2.3-fold) for training groups collapsed and compared with Con. CD14 mRNA, expressed per monocyte, was significantly lower immediately after resistive exercise for NHR, HRT, and MIB compared with Con. There were few significant effects detected for IL-6, IL-1beta, and TNF-alpha mRNA, but there was a significant group effect (P < 0.0001) for TNF-alpha mRNA expressed per monocyte (Con > HRT, NHR, MIB). These findings suggest that there may be a resistive exercise training-induced reduction in TLR4/CD14 expression in older women. Further research is needed to determine whether lower TLR4/CD14 could explain the lower LPS-stimulated inflammatory cytokines observed in these women.

A Toxicokinetic Study of Nickel‐Induced Immunosuppression in Rats

The aim of the present study was to investigate dose- and time-dependent effects of NiCl2 on T-lymphocyte and macrophage-derived cytokine production in rats. Moreover we have determined the concentrations of nickel in the plasma that are required to elicit alterations in T-lymphocyte and macrophage function. NiCl2 suppressed T-lymphocyte proliferation and Th1 (IFN-gamma) and Th2 (IL-10) cytokine production in a dose- and time-dependent fashion. In addition, NiCl2 inhibited production of the pro-inflammatory cytokine TNF-alpha and increased production of the anti-inflammatory cytokine IL-10 from lipopolysaccharide (LPS) stimulated cultures. We have determined that the minimal plasma concentrations of nickel required to provoke immunosuppression are in the range 209-585 ng/mL. In the time-course study NiCl2 (3.3 mg/kg) provoked immunological changes that were maximal 1 h following administration, and some of these changes persisted for up to 24 h post administration. Overall these data clearly demonstrate that NiCl2 suppresses T-cell function and promotes an immunosuppressive macrophage phenotype in rats. This study also indicates that measuring T-cell proliferation is as sensitive a marker of NiCl2-induced immunotoxicity as measuring T-cell or macrophage cytokine production. Co-measurement of circulating nickel concentrations and immune parameters yields valuable information with regard to the potency of nickel to alter immune function in vivo. These data also suggest that quite a large quantity of nickel needs to reach the systemic circulation before any adverse effects on immune function are observed.

Effect of calcitonin gene-related peptide, neuropeptide Y, substance P, and vasoactive intestinal peptide on interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha production by peripheral whole blood cells from rheumatoid arthritis and osteoarthritis patients

In the present study, we have investigated the in vitro effect of calcitonin-related peptide (CGRP), neuropeptide Y (NPY), substance P (SP) and vasoactive intestinal peptide (VIP) at concentrations of 10(-8), 10(-9) and 10(-10) M on the production of different proinflammatory cytokines or chemokines such as IL-1beta, IL-6 and TNFalpha by peripheral whole blood cells from patients with rheumatoid arthritis, as well as from osteoarthritis patients studied as a control group without immunoinflammatory background. We have found that CGRP, NPY, SP and VIP stimulated significantly the production of those cytokines and chemokines in rheumatoid arthritis patients. In general, the stimulation was higher at the 10(-9) M concentration, with SP and VIP, and in rheumatoid arthritis patients compared to osteoarthritis ones. Neuropeptides did not significantly modify the LPS-induced cytokine production by whole blood cells. The results indicate that physiological concentrations of the neuropeptides studied can modulate the inflammatory and immunological response, stimulating significantly the production of inflammatory cytokines by human whole blood cells in rheumatoid arthritis patients, as well as, in a minor way, in osteoarthritis patients.

Endotoxin contamination in wound dressings made of natural biomaterials

Contamination by endotoxin of nine kinds of wound dressings made of natural biomaterials (calcium alginate, collagen, chitin, and poly-L-leucine) was examined with the use of water extracts. By applying the Limulus amoebocyte lysate (LAL) test, high concentrations of endotoxin were detected in extracts from three kinds of products made of calcium alginate. These extracts evoked fever in rabbits and induced the release of a proinflammatory (pyrogenic) cytokine, interleukin-6 (IL-6), from human monocytic cells (MM6-CA8). The effects disappeared when the extracts were treated with endotoxin-removing gel column chromatography or with an endotoxin antagonist, B464, confirming that the contaminating pyrogen was endotoxin. A noteworthy finding was that one of the endotoxin-containing extracts showed very weak IL-6-inducibility in human monocytic cells in contrast to its high pyrogenicity to rabbits. The discrepancy could be explained based on differences between humans and rabbits in sensitivity to the endotoxin, because the extract showed higher proinflammatory-cytokine (TNF-alpha)-inducibility in rabbit whole-blood cells (WBCs) than human WBCs. The results suggest that the LAL test is a useful method of detecting endotoxin contamination in wound dressings and the MM6-CA8 assay is a good supplement to the LAL test for evaluating pyrogenicity in humans accurately.

Reduced glucocorticoid sensitivity of monocyte interleukin-6 production in male industrial employees who are vitally exhausted

OBJECTIVE

Proinflammatory changes are thought to link vital exhaustion with adverse cardiovascular outcomes. Monocytes play a central role in the pathogenesis of atherosclerotic lesions and are a major source of circulating cytokines. We hypothesized that vital exhaustion may alter the regulation of monocyte activity, as measured by lipopolysaccharide (LPS)-stimulated and glucocorticoid inhibited release of the proinflammatory cytokine interleukin-6 (IL-6).

METHODS

In 166 middle-aged apparently healthy men, vital exhaustion was measured by the Shortened Maastricht Exhaustion Questionnaire. Subjects in the highest quartile (highly exhausted, N= 38) were compared with those in the second and third quartiles (moderately exhausted N= 89) vs. those in the lowest quartile (nonexhausted, N= 39) in terms of plasma C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-alpha) levels, and as to IL-6 release after LPS stimulation in vitro. Inhibition of IL-6 release was determined by coincubation with increasing concentrations of dexamethasone. Monocyte glucocorticoid sensitivity was defined as the dexamethasone concentration inhibiting IL-6 release by 50%.

RESULTS

Highly exhausted individuals had higher CRP levels than nonexhausted subjects (p=.008). LPS-stimulated IL-6 release was not significantly different between groups. However, in highly exhausted participants, dexamethasone was less able to inhibit IL-6 release (p=.010), and the glucocorticoid sensitivity was lower (p=.003) than in nonexhausted subjects.

CONCLUSIONS

In highly exhausted individuals, glucocorticoids exert less suppressive action on monocyte IL-6 release than in nonexhausted subjects. This finding points to altered regulation of monocyte cytokine production as one possible pathway linking exhaustion with atherosclerosis.

In vitro effects of eicosanoids derived from different 20-carbon fatty acids on T helper type 1 and T helper type 2 cytokine production in human whole-blood cultures

BACKGROUND

Different series prostaglandins (PGs) and leukotrienes (LTs) are synthesized from different 20 carbon fatty acid precursors. The effects of the different series of PGs and LTs on production of T helper type 1 (Th1) and Th2 cytokines by human cells are not well established.

OBJECTIVE

To characterize the influence of PGs and LTs produced from different fatty acid precursors on the Th1 and Th2 cytokine profile in mitogen-stimulated human whole-blood cultures.

METHODS

Blood from healthy adult males was diluted and cultured with concanavalin A in the presence or absence of a range of concentrations of various PGs or LTs. Cytokine concentrations in culture supernatants were analysed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

PGE1, PGE2 and PGE3 significantly and dose-dependently decreased the concentrations of the Th1 cytokines IL-2 and IFN-gamma by up to 50% and 70%, respectively. The three PGs exhibited similar potency towards IFN-gamma production. At the highest concentration used (10-6 m) PGE1, but not PGE2 or PGE3, increased the concentration of the Th2 cytokine IL-4 by about 70%. IL-10 production was not affected by PGs. The ratio of the concentrations of IFN-gamma to IL-4 was significantly decreased at PGE concentrations of 10-7 and 10-6 M with all three PGEs having similar effects. LTB4, LTC4 and LTC5 did not significantly affect production of the cytokines studied.

CONCLUSION

PGE produced from different fatty acids significantly decrease Th1 cytokine production resulting in a shift in the Th1, Th2 balance in favour of a Th2 response. PGE produced from different fatty acid precursors are equipotent in their effects on human T lymphocytes. Thus, although changes in the pattern of dietary fatty intakes may contribute to the increased prevalence of atopic disease, this would probably not be mediated through substitution of one PGE with another from a different series. It may, however, be mediated through a change in the total amount of PGE produced at the site of antigen presentation.

Impaired production of cytokines is an independent predictor of mortality in HIV-1-infected patients

OBJECTIVES

With regard to the natural history of HIV-1 infection this study investigated whether whole-blood culture cytokine production was associated with mortality in HIV-1-infected patients.

DESIGN AND METHODS

One hundred and seven HIV-1-infected patients stratified according to the Centers for Disease Control and Prevention criteria and 65 controls participated. The 24-h phytohaemagglutinin and lipopolysaccharide-stimulated whole-blood culture production of tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL) receptor antagonist (-ra), IL-1beta, IL-12, IL-10, IL-2 and soluble (s) IL-2 receptor (-r)alpha were studied and progression was evaluated using Kaplan-Meier method and Cox proportional-hazards models.

RESULTS

Compared with controls, asymptomatic patients had increased production of IL-1beta and IL-12 (both P< 0.05), unchanged production of TNF-alpha, IFN-gamma and IL-1ra and notably reduced production of IL-10, IL-2 and sIL2-ralpha (all P< 0.05). HIV progression led to a progressive decline in whole-blood culture production of TNF-alpha, IFN-gamma, IL-1ra, IL-1beta, IL-12, IL-10 and IL-2 (all P< 0.0001). Low production of these cytokines were all associated with increased mortality risk in the patients (log-rank test, all P < 0.01, univariate Cox, all P< 0.001). Furthermore, low production of TNF-alpha, IL-1beta, IL-12 and IL-10 independently predicted mortality after adjusting for other known prognostic variables (multivariate Cox, all P< 0.05).

CONCLUSIONS

Preserved capacity of blood cells to produce cytokines was associated with prolonged survival in HIV-1-infected patients indicating a clinical significance of impaired cytokine production in HIV-1 infection.

A rapid 'one-plate' in vitro test for pyrogens

A rapid, 'one-plate' monocyte-activation test is described for detecting endotoxin and non-endotoxin pyrogens in parenteral medicinal products. The one-plate test offers useful gains over conventional 'two-plate' (cell culture plate+ELISA plate) tests in terms of its limit of detection, robustness, speed and cost. The 'one-plate' test is likely to be applicable to a wide range of products because it allows less time for product interference in the test. The 'one-plate' test utilises pyrogen-free anti-cytokine (interleukin (IL)-6 or tumour necrosis factor alpha (TNFalpha)) antibodies (Ab), coated and stabilised onto (pyrogen-free) 96-well plates. Monocytes/monocytic cells, endotoxin (lipopolysaccharides, LPS) standard or sample and (pyrogen-free) second (labelled) Ab are cultured together (usually for 2-4 h) on the Ab-coated plate and then the plate is washed and the ELISA completed. There is no transfer from one plate to another and no (further) incubations of (released) cytokine with, first, coating Ab and, then, developing Ab since these steps have already taken place during the initial cell culture. The rapid, 'one-plate' test is readily automated. The preferred readout is IL-6, which gives a limit of detection of 0.015 endotoxin units (EU)/ml with peripheral blood mononuclear cell (PBMNC), 0.03 EU/ml with diluted whole blood and 0.05 EU/ml with a monocytic cell line (MONO MAC 6).

Chronic insomnia and immune functioning

OBJECTIVE

The goal of this study was to investigate whether clinical insomnia is associated with immune alterations by comparing immune functioning between patients with chronic insomnia and good sleepers.

METHODS

The good sleepers group was composed of 19 adults with a regular sleep schedule and no complaint of sleep disturbances. The insomnia group was composed of 17 adults meeting criteria for a chronic primary insomnia disorder. Peripheral blood samples were taken at the interview (time 1) and before the second night of polysomnographic assessment (time 2) for immune measures, including enumeration of blood cell counts (ie, white blood cells, monocytes, lymphocytes, and CD3+, CD4+, CD8+, and CD16+/CD56+ cells), natural killer cell activity, and cytokine production (ie, interleukin-1beta, interleukin-2, and interferon gamma).

RESULTS

Significant between-group differences were observed for CD3+, CD4+, and CD8+ cells, with higher levels found in good sleepers. In addition, a significant group-by-time interaction was found on monocyte counts. Although this was the only significant interaction effect observed, between-group differences were greater at time 2.

CONCLUSIONS

This study suggests that chronic insomnia is associated with some immune alterations. More research is needed to determine the clinical significance of these findings.

Cytokine response to endotoxin in individuals heterozygous for the Delta32 mutation of chemokine receptor CCR5

Studies of mice with a targeted disruption of the CCR5 gene suggest that the CC chemokine receptor 5 (CCR5) is a determinant of the cytokine response to endotoxin. In humans, a naturally occurring mutation of the CCR5 gene is a 32-basepair (bp) deletion which precludes the translation of the gene into a functional transmembrane protein. To evaluate the cytokine phenotype of heterozygosity for the 32 deletion, we studied the endotoxin-stimulated release of tumor necrosis factor-alpha, Interleukin (IL)-6, IL-8, IL-10, and IL-12 in whole blood ex-vivo of healthy volunteers and patients undergoing elective cardiac bypass surgery. This operation represents a major surgical trauma associated with ischemia-reperfusion-injury and triggers a profound inflammatory response. In these patients, cytokine plasma concentrations were measured during and after cardiac surgery. No difference was found between the frequencies of the observed and expected CCR5 genotypes in the groups of individuals studied. Furthermore, no significant difference in ex-vivo or peri- and postoperative cytokine plasma concentrations was detected between CCR5 wild-type homozygotes and individuals carrying one defective CCR5 allele. Our results indicate that heterozygosity for the 32bp deletion of CCR5 is not associated with an altered cytokine response to endotoxin or to a major surgical trauma when compared with individuals homozygous for the wild-type allele.

Production of lymphocyte-derived cytokines by whole umbilical cord blood cultures stimulated with mitogens and allergens

A whole blood culture technique was used to establish conditions for stimulating the production of cytokines by cord blood lymphocytes. The cultures were stimulated with mitogens (concanavalin A and phytohaemagglutinin) and allergens (beta-lactoglobulin (BLG), ovalbumin (OVA) and house dust mite (Der p 1)) at a range of concentrations. Interleukin (IL-) 2, IL-4, IL-10, IL-13 and interferon-gamma (IFN-gamma) concentrations were assayed in the supernatants at 24, 48 and 72 h. Stimulation with mitogens but not allergens induced increases in IL-2 and IL-13 concentrations. IFN-gamma was strongly induced by mitogenic stimulation: maximal responses were seen at 48 h. Stimulation with the allergens also induced an increase in IFN-gamma concentration which was maximal for 100 microg/ml of BLG and OVA. Der p 1 induced the highest IFN-gamma production among the allergens. IL-4 concentrations were increased in mitogen and Der p 1 stimulated cultures. This was maximal at 48 and 24 h, respectively. IL-10 was induced with mitogen and allergen stimulation. Thus, this study has established conditions for assessing production of lymphocyte-derived cytokines in a simple whole umbilical cord blood culture system.

Delay in processing porcine whole blood affects cytokine expression

Quantification of cytokine messenger ribonucleic acid (mRNA) in blood samples has become an important tool in the investigation of immune cell activation in a variety of clinical settings. It has been shown that the method of sample collection and processing influences the levels of several cytokine mRNAs. Therefore, it is generally accepted that blood samples for analysis of cytokine expression be processed as soon as possible and under standardised conditions. Since immediate sample processing is not always possible, we investigated the effect of different storage conditions (room temperature (Rt) and 4 degrees C) and storage times (1, 2, 4, 6 and 24 h) on the mRNA level of different cytokines (IL-1alpha, IL-2, IL-6, IL-8, IL-10, IFN-gamma), as well as the IL-2 receptor (IL-2R) in porcine whole blood samples (n=8). Quantification of cytokine expression was performed using simultaneous reverse transcription PCR (RT-PCR) combined with the expression of the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a reference. Our data demonstrate that delays in sample processing longer than 1 h result in significant changes of the mRNA levels of individual cytokines. Expression of the monokines IL-1alpha, IL-6 and IL-10 were increased by storage at both room temperature and 4 degrees C. Expression of IL-8 was increased only in the samples stored at room temperature, and expression of IFN-gamma was raised exclusively in the samples stored at 4 degrees C. We conclude that porcine blood samples should be processed within 2 h to prevent undesired stimulatory effects on the cytokine expression pattern. However, if only selected cytokines are investigated, the undesired effects of prolonged storage can be selectively suppressed by choosing the appropriate temperature of sample storage.

Decreased frequency of intracellular IFN-gamma producing T cells in whole blood preparations from patients with atopic dermatitis

There have been contradictory reports on the shift in the T-cell cytokine expression pattern of peripheral blood mononuclear cells from patients with atopic dermatitis (AD); more specifically the interleukin (IL)-4 and interferon (IFN)-gamma profiles. The aim of this study was to shed further light on this contradiction by measuring the intracellular cytokines IL-4 and IFN-gamma by flow cytometry on unseparated whole blood to obtain results that, as accurately as possible, reflect the situation in circulating cells in vivo. The patient group including 64 patients with AD was compared with 18 nonatopic healthy adults. The results showed that the percentage of CD4+ T cells expressing IFN-gamma was significantly decreased (P < or = 0.001), as well as the percentage expressing IL-4 (P < 0.05) in AD patients compared with healthy controls. Furthermore, in supernatants from whole blood samples stimulated with phorbol 12-myristate 13-acetate and ionomycin, production of IFN-gamma was significantly decreased, while IL-4 production remained unchanged in AD patients compared with healthy controls. We also investigated if there was a relationship between serum IgE level and Phadiatop, a screening test for atopy, vs. the levels of IL-4 and IFN-gamma, but found no correlation with either. However, there was a significant correlation between disease severity and the level of total IgE (r = 0.67, P < 0.05). In conclusion, our results support the evidence for a decreased ability of peripheral CD4+ T cells to produce IFN-gamma among AD patients.

Novel method for detection of ex vivo tumor necrosis factor alpha production by monocytes

Tumor necrosis factor alpha (TNF-alpha) has come into recent focus as a proinflammatory cytokine derived from monocytes/macrophages. We developed a novel system (the SEK-5001 system) for measurement of ex vivo production of TNF-alpha stimulated by lipopolysaccharide (LPS) as a marker of immune function. In the present study, we evaluated the performance of this system as a diagnostic tool. Furthermore, we compared TNF-alpha levels with data from other immune function tests, including lymphocyte blast formation test and differential leukocyte counts. Incubation of whole blood with a stimulation of low-dose LPS (100 EU/mL blood) for 4 hr at 37 degrees C gave acceptable results. After incubation, plasma TNF-alpha levels were determined by enzyme-linked immunosorbent assay (ELISA). The specificity, reproducibility, and recovery of the SEK-5001 system were excellent. No correlation between TNF-alpha levels and total leukocyte counts was found. Lymphocyte blast formation test and monocyte counts, however, were correlated with TNF-alpha levels in blood from patients with hematological malignancy and aplastic anemia before treatment. This assay system may potentially be clinically applicable to assess in vivo immune function.

Stabilization of mRNA Expression in Whole Blood Samples

Background: Accurate quantification of mRNA in whole blood is made difficult by the simultaneous degradation of gene transcripts and unintended gene induction caused by sample handling or uncontrolled activation of coagulation. This study was designed to compare a new blood collection tube (PAXgeneTM Blood RNA System) and a companion sample preparation reagent set with a traditional sample collection and preparation method for the purpose of gene expression analysis.

Methods: We collected parallel blood samples from healthy donors into the new sample collection tubes and control EDTA tubes and performed serial RNA extractions on samples stored for 5 days at room temperature and for up to 90 days at 4 and 20 °C. Samples were analyzed by Northern blot analysis or reverse transcription-PCR (RT-PCR).

Results: Specific mRNA concentrations in blood stored in EDTA tubes at any temperature changed substantially, as determined by high-precision RT-PCR. These changes were eliminated or markedly reduced when whole blood was stored in PAXgene tubes. Loss of specific mRNAs, as measured by RT-PCR, reflected total RNA depletion as well as specific mRNA destruction demonstrated by Northern blot analysis. The salutary effects of PAXgene on mRNA stabilization extended to blood samples from eight unrelated donors.

Conclusions: Compared with whole blood collected in EDTA tubes and extracted by an organic method, the PAXgene Blood RNA System reduced RNA degradation and inhibited or eliminated gene induction in phlebotomy whole blood samples. Storage of whole blood samples in PAXgene tubes can be recommended for clinically related blood samples that will be analyzed for total or specific RNA content.

The effect of soluble beta-1,3-glucan and lipopolysaccharide on cytokine production and coagulation activation in whole blood

Soluble beta-1,3-glucan has been demonstrated to protect against infection and shock in rats and mice, and clinical studies suggest that administration of soluble glucans to trauma/surgical patients decreases septic complications and improves survival. However, little is known about the precise mechanisms by which glucans influence the state of activation of blood cells, which are responsible for the fulminant cytokine production and the activation of the coagulation system observed in serious gram-negative infection. We studied therefore the effect of an underivatized, soluble yeast beta-1,3-glucan and lipopolysaccharide (LPS), either alone or in combination, on tumor necrosis factor-alpha (TNFalpha), interleukin-6 (IL-6), IL-8 and IL-10 secretion and monocyte tissue factor (TF) expression in human whole blood. As expected, LPS induced the secretion of substantial amounts of all measured parameters, whereas only minor amounts of TNFalpha, IL-6, and IL-10 were induced by beta-glucan itself. However, beta-glucan itself induced the production of significant amounts of IL-8 and TF. Soluble beta-1,3-glucan had a strong synergistic effect on the LPS-induced secretion of IL-8, IL-10, and on monocyte TF activity, but not on TNFalpha and 1L-6 production. On the other hand, soluble beta-glucan strongly primed LPS stimulation of all parameters, including TNFalpha and IL-6. beta-Glucan also induced detectable neutrophil degranulation within 15 min, whereas a response to LPS was first detected after 90 min. In conclusion, soluble beta-1,3-glucan upregulated leukocyte activity, both on its own and in concert with LPS.

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.

Production of IL-1beta and IL-1Ra as risk factors for susceptibility and progression of relapse-onset multiple sclerosis

Interleukin-1beta (IL-1beta) is present in multiple sclerosis (MS) lesions. Interleukin-1 receptor antagonist (IL-1Ra) moderates the induction of experimental autoimmune encephalomyelitis (EAE). Here, we show that families that are characterized by high IL-1beta over IL-1Ra production ratio are at 2.2-fold (95% CI, 1.0-4.8; p=0.05) increased risk to have a patient relative with relapse-onset MS than families with a low ratio. It is also related to the reduction of volumetric magnetization transfer ratio (MTR) histogram height, a measure of parenchymal integrity (p=0.04). Those families who combine a high IL-1beta over IL-1Ra ratio with a high tumor necrosis factor (TNF) over IL-10 production ratio have a 6.2-fold (95% CI, 1.8-21; p=0.002) increased risk. Innate production of IL-1beta and IL-1Ra is not related to the outcome of primary progressive MS. Taq1 polymorphism in the IL-1beta gene and the variable number of tandem repeats (VNTR) polymorphism of 86-base pairs within the IL-1Ra gene cannot explain these findings.

Evaluation of the in vitro pyrogen test system based on proinflammatory cytokine release from human monocytes: comparison with a human whole blood culture test system and with the rabbit pyrogen test

The reliability of an in vitro pyrogen test system based on proinflammatory cytokine release from human monocytic cells was assessed by comparison with a test system based on a human whole blood culture as well as with the conventional rabbit pyrogen test. The human cells used as the pyrogen indicator cells were newly selected by subcloning of a human monocytic cell line, Mono-Mac-6. The selected cells, named MM6-CA8, responded to various pyrogens, including endotoxin, peptidoglycan (PG), Staphylococcus aureus Cowan 1 (SAC), and poly(I x C), with a high sensitivity and produced proinflammatory cytokines, such as interleukin 1 (IL-1), IL-6, and tumor necrosis factor alpha. Among these cytokines, IL-6 was produced most sensitively in response to traces of the pyrogens and detected in the largest quantities in the culture medium. The cytokine-producing responses of MM6-CA8 cells correlated significantly with the responses of cultured human whole blood, which represents an ex vivo culture test system reproducing pyrogen-induced cytokine production in the human body. In terms of cytokine inducibility, the pyrogens were ranked in the order endotoxin > PG > poly (I. C) > SAC in both culture systems, a ranking which almost agreed with the ranking of their pyrogenicity as assessed by the rabbit pyrogen test. These results suggest that the in vitro responsiveness of MM6-CA8 cells to various pyrogens is highly relevant for human pyrogenic reactions. Therefore, the in vitro test system is useful and reliable for detecting the presence of materials that are pyrogenic for humans.

Defective regulation of the proinflammatory immune response in women with vulvar vestibulitis syndrome

OBJECTIVE

The cause of vulvar vestibulitis syndrome is unknown. To determine a possible role for defective immune regulation in this chronic condition, proinflammatory and anti-inflammatory immune responses to the 70-kd heat shock protein and to lipopolysaccharide were compared in women with and without vulvar vestibulitis syndrome.

STUDY DESIGN

Whole blood cultures from 62 women with vulvar vestibulitis syndrome and 48 control subjects were incubated in the presence or absence of 5 microg/mL human recombinant 70-kd heat shock protein or 0.1 ng/mL lipopolysaccharide for 18 hours. The culture supernatants were then assayed for interleukin-1 beta and interleukin-1 receptor antagonist by enzyme-linked immunosorbent assay.

RESULTS

Median levels of interleukin-1 beta were higher in response to heat shock protein in cultures from patients with vulvar vestibulitis syndrome (median, 1.07 ng/mL) as opposed to control subjects (median, 0.40 ng/mL; P =.006). Conversely, levels of interleukin-1 receptor antagonist were higher in response to heat shock protein in control subjects (median, 39.21 ng/mL) than in patients (median, 29.25 ng/mL; P =.009). In response to lipopolysaccharide, median levels of interleukin-1 beta were similar in patients (1.00 ng/mL) and control subjects (1.15 ng/mL); median interleukin-1 receptor antagonist concentrations were higher in control subjects (70.0 ng/mL) than in patients (44.3 ng/mL; P <.0001). The ratio of interleukin-1 receptor antagonist to interleukin-1 beta was higher in control subjects than in women with vulvar vestibulitis syndrome in response to both heat shock protein (P =.0002) and lipopolysaccharide (P =.01). In uninduced cultures, interleukin-1 receptor antagonist levels were also higher in control subjects (median, 1.60 ng/mL) than in patients with vulvar vestibulitis syndrome (median, 0.62 ng/mL; P <.0001).

CONCLUSION

A relative inability to down-regulate proinflammatory interleukin-1 beta activity by interleukin-1 receptor antagonist may contribute to the pathophysiologic features of vulvar vestibulitis syndrome.

TNFalpha production in whole blood cultures from healthy individuals

Tumor necrosis factor alpha (TNFalpha) is a major mediator of inflammatory responses and also plays a prominent role in bridging the innate and adaptive phases of immunity. In the present work we attempted to study TNFalpha production in endotoxin-stimulated blood of healthy individuals, and the inter-individual variability in TNFalpha production. For this study, we used diluted whole blood stimulated with lipopolysaccharide (LPS). The levels of the pro-inflammatory cytokine TNFalpha were measured by ELISA and by the L929 cytotoxicity bioassay in 16 and 18 healthy donors, respectively. There were highly significant inter-individual variations in the induced TNFalpha production. It is worth noting that there was no difference in sensitivity between ELISA and the cytotoxicity L929 bioassay. We concluded that whole blood culture is a sensitive method to determine the pro-inflammatory cytokine production in response to endotoxin stimuli in a relevant physiologic milieu. Our data indicate that this method provides appropriate information about the state of cellular immunity of the individual.

A deficiency in interferon-alpha production in women with vulvar vestibulitis

OBJECTIVE

Previous studies have suggested that interferon-alpha may be an effective treatment for some women with vulvar vestibulitis. We evaluated whether women with this syndrome had a deficiency in endogenous and induced interferon-alpha production.

STUDY DESIGN

Blood was collected in heparinized tubes from 62 women with vulvar vestibulitis and 47 control women of similar age and ethnicity. Whole blood cultures were incubated in the presence of 0.1 ng/mL lipopolysaccharide (induced) or culture medium (uninduced) for 18 to 20 hours. Aliquots were tested for interferon-alpha levels by enzyme-linked immunosorbent assay. Vestibular samples were tested for human papillomavirus by polymerase chain reaction. Aliquots were also characterized for alleles of the polymorphic gene, interleukin-1 receptor antagonist, by polymerase chain reaction.

RESULTS

In uninduced cultures, interferon-gamma was present in 68.1% of control subjects as opposed to 33.9% of vulvar vestibulitis patients ( P =.0005). Similarly, after lipopolysaccharide stimulation, 70.2% of control subjects and only 48.4% of patients produced interferon-alpha ( P =.03). Among the positive samples, however, there were no differences in the interferon-alpha levels between patients and control subjects. In contrast, induction of interferon gamma in response to lipopolysaccharide was similar in control subjects (78.0%) and vulvar vestibulitis patients (82.1%). Women who have a deficiency in interferon-alpha production did not have an increased prevalence of human papillomavirus infection. There was no relation between interleukin-1 receptor antagonist genotype and interferon-alpha production.

CONCLUSION

An inability to produce interferon-alpha may contribute to chronic vestibular inflammation in some women.

Attenuated production of intracellular IL-10 and IL-12 in monocytes from patients with severe asthma

Interleukin (IL)-10 and IL-12 production is decreased in peripheral blood mononuclear cells of patients with mild asthma. Using whole blood culture and flow cytometry we examined whether monocyte heterogeneity influenced IL-10 and IL-12 production in subjects with severe asthma. We demonstrated that IL-10 release in LPS-stimulated whole blood culture was decreased in patients with severe persistent asthma compared to those with mild asthma and controls (P = 0.04 and P < 0.001, respectively). In asthmatic patients, the percentage of CD14(+)CD16(+) cells was higher than that from normal subjects (P = 0.04). Severe asthmatics showed significantly less positive staining for IL-10 and IL-12 (P < 0.001 and P = 0.02, respectively) after stimulation in monocytes, compared to mild asthmatics and controls in both CD14(+)CD16(+) and CD14(+)CD16(minus sign) cells. These results suggest that IL-10 synthesis is attenuated in severe persistent asthma compared to mild asthma and that this cannot be explained by the increase in the CD14(+)CD16(+) monocytes in asthma.

Enhanced interleukin-6 and interleukin-8 synthesis in term and preterm infants

There is growing evidence that sepsis-related complications in neonates are crucially mediated by the action of proinflammatory cytokines. It has previously been demonstrated that elevated IL-6 and IL-8 levels can predict brain damage and chronic lung disease in preterm infants. However, it is the current view that neonates have a reduced capability to produce proinflammatory cytokines. To clarify this issue, we analyzed the inflammatory response in term and preterm infants directly at the single cell level by flow cytometry. Endotoxin challenge was performed under defined conditions on monocytes obtained from 50 healthy adults and 119 neonates, which consist of 45 term infants, 63 preterm infants (26.1-36.7 wk of gestational age), and 11 preterm infants with proven infection (24.6-29.9 wk). Our results challenge the existing view of an immature inflammatory response by demonstrating that term infants and preterm infants display a higher percentage of IL-6- and IL-8-positive cells than adults. After preincubation with dexamethasone the number of cytokine-positive cells decreased in all groups, but the number of IL-8-positive cells remained higher in term and preterm infants >32 wk compared with adults. These observations demonstrate not only a well-developed but also an enhanced inflammatory response in term and preterm infants. Under consideration of several detrimental effects of IL-6 and IL-8, our data may have major implications on the pathophysiology of inflammatory-triggered neonatal diseases.

Severe hypertriglyceridemia with insulin resistance is associated with systemic inflammation: reversal with bezafibrate therapy in a randomized controlled trial

PURPOSE

To determine whether hypertriglyceridemia is associated with systemic inflammation, which may contribute to the increased cardiovascular risk in patients who have hypertriglyceridemia. In addition, we investigated whether fibrates reverse this inflammatory state.

PATIENTS AND METHODS

Serum lipid levels, body mass index, insulin resistance, and inflammatory parameters were compared between 18 patients who had severe hypertriglyceridemia without cardiovascular disease and 20 normolipidemic controls. We measured the ex vivo production capacity of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 after whole-blood stimulation with lipopolysaccharide, as well as circulating levels of C-reactive protein and fibrinogen. A randomized controlled trial was conducted to determine whether bezafibrate (400 mg administered daily for 6 weeks) affected these parameters in hypertriglyceridemic patients.

RESULTS

When compared with normolipidemic controls, hypertriglyceridemic patients had significantly lower high-density lipoprotein (HDL) cholesterol and higher triglyceride levels, body mass index, and insulin resistance. In addition, hypertriglyceridemic patients had a significantly higher production capacity of TNF-alpha (mean difference, 11 700 pg/mL; 95% confidence interval [CI]: 7800 to 15,700 pg/mL]) and IL-6 (mean difference, 20,400 pg/mL; 95% CI: 7800 to 32,900 pg/mL), and higher levels of C-reactive protein (mean difference, 0.8 mg/L; 95% CI: 0.1 to 2.4 mg/L) and fibrinogen (mean difference, 0.8 g/dL; 95% CI: 0.3 to 1.3 g/dL). Bezafibrate therapy significantly increased HDL cholesterol levels, reduced triglyceride and insulin resistance levels, and reduced production capacity of TNF-alpha and IL-6, as well as levels of C-reactive protein and fibrinogen.

CONCLUSION

Systemic inflammation is present in patients who have the clinical phenotype that is associated with severe hypertriglyceridemia, and may contribute to the increased risk of cardiovascular disease in these patients. Bezafibrate has anti-inflammatory effects in these patients.

Influence of specimen age and use of different negative controls in determination of intracytoplasmic levels of cytokines after whole-blood culture assay

Intracytoplasmic detection of cytokines by flow cytometry has become a powerful tool in the characterization of cytokine-producing cells. However, it is not known to what extent specimen age and the use of various negative controls may influence the amount of cytokine-positive cells. We therefore compared different times of storage and the use of several negative controls in the determination of intracytoplasmic levels of cytokines. There was a substantial decline of interleukin-2- and gamma interferon-positive lymphocytes after 20 h and especially after 48 h of storage. The precision of intracytoplasmic interleukin-6 determination decreases after long-term storage compared to 2 h of storage, whereas the amount of interleukin-8-positive monocytes remained rather stable. Therefore, we recommend performing the analysis as fast as possible after the blood sample is drawn. Under consideration of isotype-matched antibodies and nonstimulated cells as negative controls instead of the purified antibody-blocking control, strikingly higher amounts of interleukin-2-, gamma interferon, interleukin-6-, and interleukin-8-positive cells were found. For a meaningful interpretation of data these differences have to be kept in mind. Further studies should evaluate the exact specificity of these controls.

Tuberculin-induced lymphocyte proliferation in whole blood: an antigen specific method for assessing immunosuppressive agents

Antigen-stimulated whole blood cultures have not been used to study the effects of immunosuppressive drugs. The aim of this study was to assess the potential usefulness of tuberculin purified protein derivative (PPD)-stimulated lymphocyte proliferation in whole blood for studying the effects of T cell inhibitory agents. We have investigated whether PPD causes antigen specific T cell proliferation, and the role of the major histocompatibility complex class II (MHC class II), co-stimulation and IL-2 in the development of this response. We have also studied the effects of prednisolone and cyclosporin on lymphocyte proliferation. Heparinised blood from healthy volunteers was diluted in culture medium and incubated with PPD. Cell proliferation, measured by liquid scintillation counting, was maximal using 1000 units/ml PPD incubated in 10% whole blood for 6-7 days. A population of large CD4+ lymphocytes appeared in cultures incubated with PPD, suggesting that the major responding population was composed of T lymphocytes. There was no significant response to the negative control antigen KLH, indicating that proliferation was antigen specific. Monoclonal antibodies (mAbs) against MHC, CD2, CD26, CD28 and IL-2 inhibited proliferation. Prednisolone was more potent than cyclosporin in this assay (IC50 values; prednisolone 20 nmol, cyclosporin 278 nmol). For the first time, this report shows that the PPD causes antigen specific lymphocyte proliferation in whole blood, which is dependent on antigen presentation via MHC class II, co-stimulation and IL-2 production. Because the proliferative response is dependent on the major interactions that lead to T cell activation, this simple assay can be used to assess the effects of novel immunomodulators.

Overproduction of monokines by leukocytes after stimulation with lipopolysaccharide in the elderly

The elderly suffer from an impaired immune function being obvious in a higher susceptibility to infections. Especially the rate of complications after infection with Salmonella, normally confined to the gastrointestinal tract, is raised. We compared in a whole blood assay and in vitro stimulation of peripheral blood mononuclear cell (PBMC) the secretion of interleukin (IL)-1-beta, IL-6, IL-8 and TNF-alpha, after stimulation with lipopolysaccharid (LPS) from Salmonella abortus equi and Escherichia coli, phytohaemagglutinin (PHA) and toxic shock syndrome toxin-1 (TSST-1) by leukocytes of healthy young donors, healthy elderly and healthy elderly fulfilling the SENIEUR protcol. Significantly higher secretion of IL-1-beta, IL-6 and IL-8 after stimulation with LPS were found in the SENIEUR elderly compared to young donors. IL-1-beta, IL-6 and IL-8 were elevated in the whole blood samples of the healthy elderly controls as well. After stimulation of whole blood samples from these healthy elderly with LPS, IL-1 and IL-6 secretion was significantly elevated, but stimulation of their PBMCs showed lower amounts of produced cytokines compared to the PBMCs of healthy young donors. The results suggest that the elvated cytokine releases are caused by an interaction of LPS with a serum factor in the blood of the elderly. Such an overproduction of these inflammatory cytokines by moncytes and neutrophils may be in part responsible for many symptoms elderly people suffer from during an infection with Salmonella.

Immune responsiveness following academic stress in first-year medical students

Many studies illustrate that physical or psychologic stressors can alter human immune function, which might predispose one to an increased susceptibility to infections. In the present study, we monitored immune responsiveness in 16 first-year medical students (age 23.8 +/- 2.2 years) during the first examination session. Baseline blood samples were collected 30 days prior to the first examination session. Subsequently, subjects were randomly assigned to two groups, and blood samples were collected at 24 h (POST24h) or 48 h (POST48h) after an examination. The percentage of CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), CD3(+)CD45RO(+), CD3(+)CD45RA(+), CD3(-)CD16(+)56(+), CD19(+), and CD14(+) cells in whole blood was examined to determine changes in circulating immune cell populations. Activation of peripheral blood mononuclear cells (PBMC) with a mixture of phorbol myristate acetate (PMA) and ionomycin or lipopolysaccharide (LPS) for 4 h was used to assess the distribution of interleukin-2 (IL-2)-secreting or interferon-gamma (IFN-gamma)-secreting CD4(+) and CD8(+) cells, as well as IL-1alpha-secreting CD14(+) cells. Activation with a combination of phytohemagglutinin (PHA) and LPS was used to assess secretion of IL-2, IFN-gamma, IL-4, IL-10, soluble IL-2 receptor-alpha (sIL-2Ralpha), IL-1beta, and IL-1R antagonist (IL-1Ra) by PBMC in 48-h cell culture. A significantly higher level of total T cells was found at POST24h, and CD14(+) was elevated at both POST24h and POST48h. The percentage of CD4(+) and CD8(+) cells significantly declined at POST24 and POST48h. A significant elevation in the percentage of memory T cells was observed at POST48h, whereas the percentage of naive T cells was elevated at POST24h and POST48h. These changes were accompanied by a significant decline in percentage of natural killer (NK) cells 24 h after the examination. The percentage of IL-2-producing CD4(+) and CD8(+) cells was significantly lower at POST24h, and the percentage of CD8(+)IFN-gamma(+) cells significantly declined at POST48h. The percentage of CD14(+)IL-1alpha(+) significantly declined at both POST24 and POST48h. A significant decrease was observed in IL-2 secretion 24 h after the examinations, and the secretion of IL-4 and IL-1beta significantly declined at POST48h. No changes in IFN-gamma, IL-10, sIL-2Ralpha, and IL-1Ra secretion were observed. We conclude that the stress outcomes of academic examinations in first-year medical students can significantly alter immune cell distribution and in vitro production and secretion of specific cytokines.

Quantitation of immunosuppression by tacrolimus using flow cytometric analysis of interleukin-2 and interferon-gamma inhibition in CD8(-) and CD8(+) peripheral blood T cells

The authors have determined the frequency of intracellular interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) synthesis by T-cell subsets in whole blood (WB) and isolated lymphocytes in 16 transplant recipients treated with tacrolimus and 10 control patients who were not transplant recipients. The authors also determined the impact of varying amounts of red blood cells (RBC) on immunosuppression by tacrolimus. Samples were analyzed by two-color flow cytometry, and the results were expressed as a ratio of whole blood to isolated lymphocytes. In healthy subjects who were not transplant recipients, the frequency of IL-2--producing CD8(-) and CD8(+) cells was higher in WB than in isolated lymphocytes (mean +/- SD of whole blood to lymphocytes ratio: 1.24 +/- 0.5 and 1.67 +/- 0.62, respectively). Adding varying amounts of RBC had no significant impact on IL-2 production by CD8(-) and CD8(+) T cells. Adding tacrolimus (10 ng/mL) to lymphocyte cultures inhibited (90%) IL-2 production in isolated T cells but not in the whole-blood assay. The dose of tacrolimus required for a 50% inhibition of IL-2 release in T cells was 10-fold higher in cultures with RBC than without. Peripheral blood mononuclear cells (PBMC) isolated from tacrolimus-treated whole blood (WB) showed less IL-2 inhibition than did lymphocytes in the WB. The authors also tested cytokine production in WB and PBMCs in 16 transplant recipients and observed various patterns of reactivity. The frequency of IL-2--producing CD8(-) and CD8(+) cells was similar using two different methods in 10 of 16 patients tested. By contrast, in the remaining six patients the authors observed a significant inhibition of IL-2 production in both CD8(-) and CD8(+) T-cell subsets in the whole-blood assay but not in the isolated lymphocytes. The frequency of CD8(-) IFN-gamma--producing cells was significantly lower in 9 of 16 patients, but the same individuals showed no inhibition of their CD8(+) IFN-gamma T cells. The trough levels of tacrolimus did not predict the level of cytokine inhibition in the whole-blood assay in these patients. The authors' results show that the whole-blood assay for cytokine production can be used for monitoring the in vivo effect of tacrolimus in transplant recipients.

Th1 and Th2 cytokine responses to academic stress

Predominant Th2 profiles are associated with the worsening of asthma, and stress is speculated to induce a Th2 profile. The goals of this study were to examine the responses of the cytokines Th1 (IFN-gamma and IL-2) and Th2 (IL-4, IL-5, and IL-6) to a stressor and to look at the relationships between cytokine and psychological responses. Twenty-four students with and without a history of asthma completed questionnaires and gave blood samples during nonexam and exam periods. Cytokines were measured by ELISA from supernatants of stimulated mononuclear cells (MNC) and whole blood. During examinations, there were a significant decrease in IL-2 and a significant increase in IL-6 production (both cultures) and a significant decrease in IFN-gamma production (MNC cultures). Baseline IL-2 levels showed significant negative correlations with several stress and mood scores. Findings of this study indicate a down-regulation of Th1 and a selective up-regulation of Th2 cytokines during a stressful exposure.