LPS耐受巨噬细胞致炎和抗炎细胞因子表达和分泌的特点

目的：分析巨噬细胞LPS耐受形成过程中致炎和抗炎细胞因子（TNF-α、IL-6和IL-10）释放的特点和规律,探讨其在巨噬细胞建立LPS耐受机制中的作用.方法：培养小鼠腹腔巨噬细胞系RAW264.7 细胞.实验分为两部分：①LPS刺激细胞不同时间（4 h,8 h,20 h）或用PBS培养细胞4 h;②LPS耐受实验（LPS预刺激巨噬细胞20 h后,换液并洗去LPS,再次加入LPS刺激4 h）.ELISA法检测细胞培养上清中TNF-α、IL-6和IL-10的浓度,RT-PCR法相对定量分析巨噬细胞TNF-α和IL-10 mRNA 表达水平.结果：细胞培养上清中TNF-α、IL-6和IL-10的浓度随着LPS刺激时间的延长而增加;LPS刺激20 h后建立耐受的巨噬细胞再次受到LPS打击时,其TNF-α释放量低于非耐受细胞,而IL-6和IL-10释放量则大幅增加,与TNF-α释放减少截然相反.TNF-α和IL-10mRNA 表达水平与其蛋白分泌量呈现相似的变化规律.结论：巨噬细胞对LPS的耐受建立在致炎因子和抗炎因子共同作用的基础上;LPS预刺激细胞再次受到LPS打击时,抑炎因子表达和分泌大幅增加是介导巨噬细胞对LPS耐受的重要机制.     

Proximal tubule cells stimulated by lipopolysaccharide inhibit macrophage activation

BACKGROUND: Tubule cells can produce a variety of cytokines, extracellular matrix (ECM) components, and adhesion molecules in vitro and in vivo. It is generally assumed that stimulated tubule cells are proinflammatory and at least partially responsible for interstitial inflammation. However, the overall effect of tubular cells on interstitial cells is unknown. In this study, pro- and anti-inflammatory cytokine production and net effects on macrophages of tubule cells activated by lipopolysaccharide (LPS) were examined. METHODS: Tubule cells stimulated with LPS expressed tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-12, monocyte chemoattractant protein-1 (MCP-1), IL-10, and transforming growth factor-beta (TGF-beta). Conditioned media were collected from confluent monolayers of rat tubule cells stimulated, or not, by LPS for 4 and 18 hours, respectively. Macrophages were cultured with conditioned media and/or LPS (0.5 microg/mL) for 18 hours. RESULTS: TNF-alpha and IL-lbeta mRNA of macrophages stimulated by LPS increased more than fivefold when cultured with control conditioned media from unstimulated tubule cells. Surprisingly, TNF-alpha and IL-lbeta levels of macrophages stimulated by LPS were not increased when cultured with conditioned media from activated tubule cells. Neutralizing antibodies to IL-10 and TGF-beta were used to define the inhibitory component(s) in conditioned medium. Anti-IL-10, but not anti-TGF-beta, abolished partially the inhibitory effects of conditioned media on macrophages. CONCLUSION: Tubule cells produce both pro- and anti-inflammatory cytokines and the net effect, partially explained by IL-10, of tubule cells activated with LPS is to inhibit activity of macrophages. Thus, the net effect of activated tubule cells on interstitial pathology may in certain circumstances, be anti- rather than pro-inflammatory.     

Impaired antigen-presenting cell function contributes to T-cell hyporesponsiveness in stable lung transplant recipients

BACKGROUND: Peripheral blood mononuclear cells (PBMC) of stable renal or cardiac transplant recipients were previously shown to respond to allogeneic cells but not to soluble protein antigens. The aim of the present study was to assess the T-cell and antigen-presenting cell (APC) functions of stable lung transplant (LT) recipients. METHODS: We obtained PBMC from 38 stable LT recipients. PBMC from healthy volunteers served as controls. PBMC were stimulated with either anti-CD3 monoclonal antibody, allogeneic PBMC, or tetanus toxoid (TT). T-cell activation was assessed by determination of interleukin (IL)-2 levels in culture supernatants; in some experiments, interferon-y levels were also determined. Patients' APC function was tested in a mixed leukocyte reaction using patients' PBMC as stimulators. The expression of class II MHC, B7.2, and CD40 molecules on patients' APC was determined by flow cytometry, and their production of IL-10 and IL-12 at the basal state and upon CD40 ligation was also measured. RESULTS: Patients' T cells produced normal amounts of IL-2 in response to anti-CD3 monoclonal antibody and allogeneic PBMC. In contrast, the response of memory T cells to TT was severely blunted both in terms of IL-2 and interferon-y production. Patients' PBMC were poor stimulators in mixed leukocyte reaction, and class II MHC expression on patients' monocytes was significantly reduced. Patients' APC presented a modest but significant increase in basal IL-10 production and produced significantly less IL-12 upon CD40 ligation than control APC. CONCLUSIONS: T cells from stable LT recipients respond normally to stimuli that do not depend on autologous APC. The major impairment in the T-cell response to TT is caused by APC dysfunction, which involves decreased class II MHC expression and deficient IL-12 synthesis.     

Mesangial cell accessory functions: mediation by intercellular adhesion molecule-1

Mesangial cell (MC) proliferation is an early pathologic alteration characteristic of many forms of immune mediated glomerulonephritis. The intracapillary position, contractile capacity, and production of cytokines and other inflammatory molecules place MC in a pivotal position to initiate, mediate, and direct glomerular damage. We as well as others have noted increased levels of cytokines including IFN gamma, TNF, and IL-1 and the cell surface MHC class II and ICAM-1 molecules in the kidneys of mice with lupus nephritis. MHC class II and ICAM-1 molecules are central to the interaction of T cells with antigen presenting cells (APC). Since cytokines can increase both MHC class II and ICAM-1 molecules, we investigated whether mesangial cells could function as APC or accessory cells after cytokine stimulation. For these studies we established a permanent MC line through transformation with origin-deficient SV40 DNA. Surface expression of ICAM-1 was similar in untransformed MC as well as SV40 transformed MC from normal mice and in untransformed cells from mice with lupus nephritis. Basal expression of ICAM-1 was upregulated rapidly by IFN gamma, TNF, and IL-1. MHC class II expression could not be induced with TNF or IL-1 alone but required prolonged stimulation with IFN gamma. MC adhered and presented antigen to an antigen specific IaK restricted T cell hybridoma. Anti-ICAM-1 mAb decreased adhesion and antigen presentation of cytokine stimulated MC. By comparison, MHC class II mAb abrogated antigen presentation by MC bearing MHC class II but did not block adhesion.(ABSTRACT TRUNCATED AT 250 WORDS)     

肝内抗炎与致炎反应变化及其与内毒素肝损伤的关系

目的 探讨内毒素致肝损伤过程中肝内致炎与抗炎反应的变化规律及其作用,为深入阐明内毒素肝损伤的发病机制提供实验依据。方法 于尾静脉注入不同剂量内毒素（E.coli 026:B6）复制内毒素血症或休克模型。采用ELISA法检测小鼠肝组织内TNFα、IL－4、IL－10含量,并分析其与肝损害的关系。结果 注射LPS后1h,低剂量和高剂量肝组织内致炎介质TNFα、IL－6水平即显著增高,其中IL－6在注射LPS后3h达峰值,至8h仍显著高于对照组。高剂量组肝内TNFα、IL－6水平明显高于剂量组。抗炎细胞因子IL－4、IL－10水平在注射LPS后1h虽均无明显变化,但至3h,两组肝内IL－4、IL－10水平都显著升高,并在8h仍显著高于对照组,其中高剂量组肝内L－4,IL－10水平也明显高于低剂量组。地内致炎和抗炎介质变化与肝组织结构受损、肝功能障碍呈一致性改变。结论 内毒素致肝损伤过程中,肝内相继发生致炎与抗炎反应, 两者相互作用失衡是导致内毒素肝损伤的重要机制。因此,在内毒素肝损伤的防治中应考虑到局部抗炎与致炎反应的综合作用。     

转化生长因子β1对脂多糖刺激大鼠腹膜间皮细胞上调表达促炎症因子的影响

目的 观察转化生长因子β1（TGF-β1）对脂多糖(LPS)刺激大鼠腹膜间皮细胞上调表达促炎症因子的影响，并探讨其可能的机制。 方法 把原代培养的第2代大鼠腹膜间皮细胞（RPMCs）分成对照组、LPS刺激组（1 mg/L）、TGF-β1刺激组（5 μg/L）及LPS+TGF-β1刺激组。RT-PCR和ELISA方法检测肿瘤坏死因子α（TNF-α）和白细胞介素6（IL-6） mRNA及蛋白的表达。蛋白印迹方法检测磷酸化核因子（p-NF）-κB/NF-κB值的变化。 结果 (1)LPS可刺激RPMCs上调TNF-α和IL-6表达。LPS刺激24 h后，p-NF-κB/NF-κB值升高。(2)TGF-β1可拮抗LPS刺激大鼠腹膜间皮细胞上调TNF-α和IL-6表达，同时，也降低p-NF-κB/NF-κB值。 结论 在体外培养的大鼠腹膜间皮细胞，TGF-β1可拮抗LPS的致炎作用，其作用机制可能是通过抑制NF-κB的活化而介导。     

Anti-inflammatory effects of lenabasum,a cannabinoid receptor type 2 agonist,on macrophages from cystic fibrosis

BackgroundLenabasum is an oral synthetic cannabinoid receptor type 2 agonist previously shown to reduce the production of key airway pro-inflammatory cytokines known to play a role in cystic fibrosis (CF). In a double-blinded, randomized, placebo-control phase 2 study, lenabasum lowered the rate of pulmonary exacerbation among patients with CF. The present study was undertaken to investigate anti-inflammatory mechanisms of lenabasum exhibits in CF macrophages.MethodsWe used monocyte-derived macrophages (MDMs) from healthy donors (n = 15), MDMs with CFTR inhibited with C-172 (n = 5) and MDMs from patients with CF (n = 4). Monocytes were differentiated to macrophages and polarized into classically activated (M1) macrophages by LPS or alternatively activated (M2) macrophages by IL-13 in presence or absence of lenabasum.ResultsLenabasum had no effect on differentiation, polarization and function of macrophages from healthy individuals. However, in CF macrophages lenabasum downregulated macrophage polarization into the pro-inflammatory M1 phenotype and secretion of the pro-inflammatory cytokines IL-8 and TNF-α in a dose-dependent manner. An improvement in phagocytic activity was also observed following lenabasum treatment. Although lenabasum did not restore the impaired polarization of anti-inflammatory M2 macrophage, it reduced the levels of IL-13 and enhanced the endocytic function of CF MDMs. The effects of lenabasum on MDMs with CFTR inhibited by C-172 were not as obvious.ConclusionIn CF macrophages lenabasum modulates macrophage polarization and function in vitro in a way that would reduce inflammation in vivo. Further studies are warranted to determine the link between activating the CBR2 receptor and CFTR.     

Irradiation with 780 nm diode laser attenuates inflammatory cytokines but upregulates nitric oxide in lipopolysaccharide-stimulated macrophages: implications for the prevention of aneurysm progression

BACKGROUND AND OBJECTIVES: Low level laser irradiation (LLLI) has been shown to reduce inflammation in a variety of clinical situations. We have shown that LLLI (780 nm) increases aortic smooth muscle cell proliferation and matrix protein secretion and modulates activity and expression of matrix metalloproteinases. Inflammation is a major component of arteriosclerotic diseases including aneurysm. Macrophage recruitment and secretion of pro-inflammatory cytokines and the vasodilator, nitric oxide (NO), are central to most immune responses in the arterial wall. The present study was designed to determine the effect of LLLI on cytokine gene expression and secretion as well as gene expression of inducible nitric oxide synthase (iNOS) and NO production in lipopolysaccharide (LPS)-stimulated macrophages. STUDY DESIGN/MATERIALS AND METHODS: Murine monocyte/macrophages (RAW 264.7) were irradiated with a 780 nm diode laser (2 mW/cm(2), 2.2 J/cm(2)) during stimulation with LPS (0, 0.1, and 1 microg/ml). Gene expression of chemokines, cytokines, and iNOS were assessed by RT-PCR. Secretion of interleukin (IL)-1beta and monocyte chemotactic protein (MCP)-1 and NO were assessed by ELISA and the Griess reaction, respectively. RESULTS: LLLI reduced gene expression of MCP-1, IL-1alpha, IL-10 (P<0.01), IL-1beta, and IL-6 (P<0.05) when cells were stimulated by 1 microg/ml LPS. LLLI reduced LPS-induced secretion of MCP-1 over non-irradiated cells by 17+/-5% and 13+/-5% at 12 hours (0.1 and 1 microg/ml LPS; P<0.01 and P=0.05, respectively), and reduced IL-1beta by 22+/-5% and 25+/-9% at 24 hours (0.1 and 1 microg/ml LPS, P=0.01 and P=0.06, respectively). However, LLLI increased NO secretion after 12 hours (LLLI vs. Control: without LPS, 1.72+/-0.37 vs. 0.95+/-0.4 microM, P<0.05; 0.1 microg/ml LPS, 7.46+/-1.62 vs. 4.44+/-1.73 microM, P=0.06; 1 microg/ml LPS, 10.91+/-3.53 vs. 6.88+/-1.52 microM, P<0.05). CONCLUSIONS: These properties of LLLI, with its effects on smooth muscle cells reported previously, may be of profound therapeutic relevance for arterial diseases such as aneurysm where inflammatory processes and weakening of the matrix structure of the arterial wall are major pathologic components.     

Murine osteoblasts respond to LPS and IFN-γ similarly to macrophages

Osteoblasts are bone-forming mesenchymal cells, while macrophages are cells of hematopoietic origin responsible for innate immunity. Lipopolysaccharide (LPS) can induce tolerance in macrophages, whereas interferon (IFN)-γ can activate macrophages to produce cytokines, exert bactericidal effects, and present antigens. In this study, we examined such macrophagic phenotypes regulated by LPS and IFN-γ in murine osteoblasts. In both primary calvarial osteoblasts and osteoblastic MC3T3-E1 cells, LPS pretreatment resulted in reduced production of IL-6 in response to a subsequent LPS stimulation or to Salmonella infection, indicating the existence of LPS-induced tolerance in osteoblasts. Furthermore, IFN-γ treatment of MC3T3-E1 cells resulted in both enhanced IL-6 production in response to LPS and upregulation of major histocompatibility complex class II (MHC II). Following infection, Salmonella-containing vacuoles (SCVs) were formed in MC3T3-E1 cells, and IFN-γ pretreatment enhanced bactericidal effects on intracellular Salmonella. Taken together, these observations indicate that osteoblasts can exhibit a subset of phenotypes reminiscent of macrophages in the course of bacterial infection.     

Assessment of immunological status in the critically ill

The systemic inflammatory response (SIRS) results from various types of injuries such as severe infection, trauma, ischemia-reperfusion and major surgery including cardiac surgery with cardio-pulmonary bypass. This response involves immune cell activation and a complex network of proinflammatory cytokines, which may induce multiple organ failure when uncontrolled. The monocyte plays a central role in the response to infection with the release of TNF, IL-1, and IL-12. In addition, monocytes present antigens to T lymphocytes. An optimal antigen presentation requires the expression of MHC class II HLA-DR on monocytes surface and of co-stimulatory molecules such as CD54 on monocytes and LFA-1 on lymphocytes. It has become increasingly apparent that the pro-inflammatory response is balanced by concomitant anti-inflammatory mechanisms that results in monocyte deactivation, characterized by a decrease in HLA-DR expression and the release of anti-inflammatory cytokines such as IL-10. This counterregulatory response, if prolonged or predominant, may predispose the patient to a higher risk of infection. Further studies need to be conducted to precise: 1) the intensity of depression of the surface molecule expression assessing monocyte function, such as HLA DR and CD54; 2) the level of IL-10 and IL-12 release in patients with severe sepsis; 3) the immunomodulating effects of frequently used treatments in these patients with severe sepsis and in surgical patients; 4) the time course of recovery; 5) if the monitoring of HLA-DR, CD54, IL-10 and IL-12 will better predict the clinical outcome than clinical parameters.     

Gene expression of pulmonary cytokines after sevoflurane or thiopentone anaesthesia in pigs

Background:  Volatile anaesthetics have diverse inflammatory effects on the lungs. They increase gene expression of some pro-inflammatory cytokines in alveolar macrophages whereas in alveolar type II cells they seem to decrease secretion and gene expression of pro-inflammatory cytokines. We have previously detected increased leukotriene C₄, nitrate and nitrite concentrations in bronchoalveolar lavage fluid after sevoflurane anaesthesia. In the current study, we measured gene expression of inflammatory cytokines in the lung tissue and plasma concentrations of cytokines in pigs after thiopentone or sevoflurane anaesthesia.
Methods:  Sixteen pigs were randomly selected to receive either a continuous thiopentone infusion (control group, n  = 8) or sevoflurane ( n  = 8) at 4.0% inspiratory concentration (1.5 MAC) in air for 6 h. Tissue samples were collected at the end of the study for measurement of gene expression of inflammatory cytokines. Blood samples were collected during anaesthesia for measurement of plasma cytokine concentrations.
Results:  Compared with thiopentone anaesthesia, lower gene expression of tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in lung tissue was observed after sevoflurane anaesthesia. Of measured cytokines IL-1β, TNF-α, IL-6, IL-8 and IL-10 only plasma concentrations of IL-6 could be measured during the study without a difference between the groups.
Conclusion:  Lower gene expression of TNF-α and IL-1β was found in the intact porcine lung tissue after sevoflurane anaesthesia compared with thiopentone anaesthesia. Clinical significance of this finding is unknown.     

Effect of prostaglandin E2 on intercellular adhesion molecule-1 and B7 expression in mixed lymphocyte reaction

BACKGROUND: The elevation of plasma interleukin (IL)-18 levels and the expression of intercellular adhesion molecule (ICAM)-1 and B7 on monocytes are involved in acute rejection. Prostaglandin (PG) E2 suppresses the rejection in animal transplantation models; however, little is known about its action mechanism. We examined the effect of PGE2 on the expression of ICAM-1 and B7 in the human mixed leukocyte reaction (MLR) in the presence or absence of IL-18. METHODS: We measured the expression of ICAM-1, B7.1, and B7.2 on human monocytes by flow cytometry and determined the associated production of interferon-gamma and IL-12 by enzyme-linked immunosorbent assay. The modulatory effects of PGE2 and the relevant PGE2 receptor subtypes were characterized pharmacologically. RESULTS: PGE2 inhibited the expression of ICAM-1, B7.1, and B7.2 on monocytes in MLR in a concentration-dependent manner. Whereas IL-18 significantly induced the expression of ICAM-1, B7.1, and B7.2 on monocytes in MLR and the production of interferon-gamma and IL-12, PGE2 inhibited these IL-18-initiated enhancements. The effects of PGE2 were mimicked by selective EP2 and EP4 agonists, but not by EP1 and EP3 agonists. CONCLUSION: PGE2 strongly inhibited MLR with respect to the expression of ICAM-1, B7.1, and B7.2 via the EP2 and EP4 receptors, irrespective of the presence or absence of IL-18. In the previous study, histamine inhibited ICAM-1 expression in the presence of IL-18 but had no effect in the absence of IL-18. These results indicate that the inhibitory effect of PGE2 may be more general and stronger than that of histamine and may play an important role in future immunosuppressive strategies.     

The combination of ciprofloxacin and indomethacin suppresses the level of inflammatory cytokines secreted by macrophages in vitro

PurposeThe combined use of antibiotics and anti-inflammatory medicine to manage bacterial endotoxin-induced inflammation following injuries or diseases is increasing. The cytokine level produced by macrophages plays an important role in this treatment course. Ciprofloxacin and indomethacin, two typical representatives of antibiotics and anti-inflammatory medicine, are cost-effective and has been reported to show satisfactory effect. The current study aims to investigate the effect of ciprofloxacin along with indomethacin on the secretion of inflammatory cytokines by macrophages in vitro.MethodsPrimary murine peritoneal macrophages and RAW 264.7 cells were administrated with lipopolysaccharide (LPS) for 24 h. The related optimal dose and time point of ciprofloxacin or indomethacin in response to macrophage inflammatory response inflammation were determined via macrophage secretion induced by LPS. Then, the effects of ciprofloxacin and indomethacin on the secretory functions and viability of various macrophages were determined by enzyme-linked immunosorbent assay and flow cytometry analysis, especially for the levels of interleukin (IL)-1β, IL-6, IL-10, and tumor necrosis factor (TNF)-α. The optimal dose and time course of ciprofloxacin affecting macrophage inflammatory response were determined by testing the maximum inhibitory effect of the drugs on pro-inflammatory factors at each concentration or time point.ResultsAccording to the levels of cytokines secreted by various macrophages (1.2 × 10⁶ cells/well) after administration of 1 μg/mL LPS, the optimal dose and usage timing for ciprofloxacin alone were 80 μg/mL and 24 h, respectively, and the optimal dose for indomethacin alone was 10 μg/mL. Compared with the LPS-stimulated group, the combination of ciprofloxacin and indomethacin reduced the levels of IL-1β (p < 0.05), IL-6 (p < 0.05), IL-10 (p < 0.01)), and TNF-α (p < 0.01). Furthermore, there was greater stability in the reduction of inflammatory factor levels in the combination group compared with those in which only ciprofloxacin or indomethacin was used.ConclusionThe combination of ciprofloxacin and indomethacin suppressed the levels of inflammatory cytokines secreted by macrophages in vitro. This study illustrates the regulatory mechanism of drug combinations on innate immune cells that cause inflammatory reactions. In addition, it provides a new potential antibacterial and anti-inflammatory treatment pattern to prevent and cure various complications in the future.     

Endotoxin induces an exaggerated pro-inflammatory response in peritoneal macrophages of children compared to adults

Background: Children have a lower incidence of post-injury multiple organ failure (MOF) compared to adults with equivalent injury severity. MOF appears to be the end result of systemic hyper-inflammation and has been correlated with increased pro-inflammatory cytokine production in adults. However, this correlation has not been examined in children. The purpose of this study was to determine the lipopolysaccharide (LPS)-induced pro-inflammatory cytokine response of pediatric vs. adult peritoneal macrophages (PM). We hypothesized that pediatric PM’s would have an attenuated pro-inflammatory response compared to adults. Methods: Human PM’s were collected during elective laparoscopic procedures and stimulated with LPS (10ng/mL). Pediatric cohort (0-16 years): n = 6 (mean 4.5 years), adult cohort (>18 years): n = 7 (mean 43 years). IL-1, IL-6 and IL-8 production were determined by ELISA. Statistical analysis was performed using ANOVA, P < 0.05 was significant. Results: LPS-induced a 27-fold increase in IL-1 production in pediatric vs. adult PM’s (378 ± 184 vs. 14 ± 7 pg/mL, P < 0.01). LPS-induced IL-8 production was also increased in pediatric vs. adult PM’s (153 ± 4 vs. 27 ± 18 pg/mL, P < 0.01). However, LPS-induced IL-6 production was not different between pediatric and adult PM’s (632 ± 12 vs. 563 ± 37, P > 0.05). Conclusions: LPS-induced macrophage production of both IL-1 and IL-8 were increased in children. There was no difference in LPS-induced IL-6 production. These data indicate that the age-related production of pro-inflammatory cytokines in resident macrophages is different in children compared to adults. Interestingly, pediatric macrophages had an augmented pro-inflammatory septic response compared to adults. Therefore, systemic hyper-inflammation may not be a proximate cause of MOF in children.     

Immune response in asymptomatic smokers

BACKGROUND: It has been demonstrated that cigarette smoking affects the immune system. Impairment of alveolar mononuclear cell function, described previously, may contribute to the higher rate of postoperative respiratory infections. However, increased susceptibility of smokers to infections of other origin (e.g. wound-related) implies that tobacco effect is not restricted to the respiratory immune competent cells. The present study was designed to investigate the systemic effect of tobacco smoking as it exerted on blood-derived immune cells. We measured systemic cytotoxic activity of natural killer cells, production of pro- and anti-inflammatory cytokines by blood mononuclear cells and their proliferation in response to mitogens. To minimize the immunosuppressive effect of other smoke-related factors, the smokers with chronic obstructive pulmonary disease (COPD) were excluded from this study. METHODS: Peripheral blood mononuclear cells (PBMC) from 24 chronic asymptomatic smokers, and 28 controls, age and gender matched, were isolated and incubated in vitro with lipopolysaccharide (LPS) or phytohemagglutinin (PHA) to induce secretion of IL-1beta, IL-1ra, IL-6, IL-10, TNFalpha and IL-2, respectively, from mononuclear cells. The level of the cytokines in the supernatants was measured using ELISA kits. The proliferative response to the mitogens PHA and concanavalin A (ConA) was evaluated by 3H-thymidine incorporation and NK cell cytotoxicity by 51Cr release assay. RESULTS: Mononuclear cells from smokers showed increased production of the pro-inflammatory cytokines IL-1beta, IL-6 and TNFalpha and enhanced proliferative response to mitogens as compared to non-smoking population. The secretion of IL-2 and the anti-inflammatory cytokines IL-1ra and IL-10 was similar in both groups. NK cell cytotoxic activity was suppressed in the smokers. CONCLUSION: Cigarette smokers without chronic obstructive pulmonary disease (COPD) exhibit impaired NK cytotoxic activity in peripheral blood and unbalanced systemic production of pro- and anti-inflammatory cytokines. These changes may serve as predisposing factors for respiratory and systemic infections in the postoperative period and should alert an anesthetist during perioperative management.