Effect of a diet supplemented with thioproline on murine macrophage function in a model of premature ageing

A previous study has shown that diet supplementation with thioproline (thiazolidine-4-carboxylic acid, TCA), an intracellular sulfhydril antioxidant and free radical scavenger, stimulates lymphocyte functions in old mice. In the present work, the effect of thioproline ingestion on the phagocytic functions of peritoneal macrophages, namely adherence, chemotaxis, phagocytosis and superoxide anion production was studied in adult female OF1-Swiss mice, that were fed thioproline (0.1% w/w) for five weeks, starting this ingestion at the age of 22 +/- 2 weeks. Mice were divided into a fast and a slow group based on their exploratory activity, which was assessed by their performance in a T-shaped maze. Slow mice showed a worse phagocytic activity with respect to fast animals. After thioproline treatment, a stimulation of all the functions studied as well as a neutralization of the superoxide radical were observed. The effect of this antioxidant was stronger in the slow than in the fast group. Thus, a diet supplemented with thioproline may enhance the immune functions, especially when they are depressed.     

N-acetylcysteine improves in vitro the function of macrophages from mice with endotoxin-induced oxidative stress

Reactive oxygen species (ROS) and proinflammatory cytokines produced by immune cells cause the oxidative stress involved in septic shock induced by endotoxin. This oxidative stress can be controlled to a certain degree by antioxidants, which is specially important for a type of immune cell, i.e. the phagocyte, that uses ROS to kill microorganisms and needs antioxidants in order to support its functions. In a previous study we have observed changes in several functions of peritoneal macrophages from BALB/c mice with lethal endotoxic shock caused by intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS) (100 mg/kg), which were associated with a high production of superoxide anion. N-acetylcysteine (NAC) is a thiolic antioxidant that improves the immune response, and we have observed that when administered intraperitoneally (150 mg/kg) at 30 min after LPS injection it counteracts the effects of LPS on macrophages and lymphocytes. In the present work, we have studied the in vitro effect of several concentrations of NAC (0.001, 0.01, 0.1, 1 and 2.5 mM) on the following functions: adherence to substrate, chemotaxis, ingestion of particles, ROS production and the release of tumor necrosis factor (TNFalpha) of peritoneal macrophages from BALB/c mice at 2, 4,12 and 24 h after LPS injection. The results show that the administration of NAC (especially at 0.1 mM) decreases raised adherence, ingestion, ROS production and TNFalpha levels in macrophages from animals injected with LPS, bringing these functions to values near those of control animals. These effects which seem to be linked to a modulation of NF-kappaB, suggest that the improvement of immune functions observed in previous work after injection of NAC to animals with endotoxic shock could be due to a direct action of this thiol antioxidant on immune cells.     

Anti-oxidants as modulators of immune function

In order to confirm the hypothesis of the immunomodulating action of anti-oxidants (bringing back altered immune function to more optimum values), the possibility that anti-oxidants may be useful in two experimental models of altered immune function has been studied. The first is a pathological model, that is, lethal murine endotoxic shock caused by an LPS injection of 100 mg/kg, in which the lymphocytes show increased adherence and depressed chemotaxis. The injection of N-acetylcysteine (150 mg/kg), which increased both functions in control animals, decreased adherence and increased chemotaxis in mice with endotoxic shock. The second is a physiological model; aged human subjects (70 +/- 5-year-old men) who, in their largest segment of population ('standard' group) showed an increased lymphocyte adherence and decreased lymphoproliferative response to mitogens compared with younger adults. The ingestion of vitamin E (200 mg daily for 3 months in this standard group) lowered adherence and stimulated lymphoproliferation. However, a smaller segment of the human population tested showed 'non-standard' values in these lymphocyte functions, that is, very low adherence and very high proliferation. In those subjects, vitamin E showed the opposite effects, namely adherence increase and depressed lymphoproliferation. In both age groups of men, these functions reached adult levels after vitamin E ingestion. These data suggest that anti-oxidants preserve adequate function of immune cells against homeostatic disturbances such as those caused by endotoxic shock and ageing.     

Changes in several functions of murine peritoneal macrophages by N-acetylcysteine and thioproline ingestion. Comparative effect between two strains of mice

The administration of the thiol compounds, N-acetylcysteine (NAC) and in particular thioproline (thiazolidine-4-carboxylic acid) at 0.1% w/w concentration in the diet, improves lymphocyte functions in old female Swiss mice, as has been shown in our previous studies. In the present work, adult mice from two different strains, namely BALB/c (an inbred strain) and OF1-Swiss (noninbred strain), were fed a diet supplemented with the above dose of each thiol compound jointly for five weeks. At 28 weeks of age, peritoneal cell suspensions were obtained and different steps of the phagocytic process, the most representative activity of macrophages, as well as interleukin-1beta (IL-1beta) production, were studied. Thus, adherence to substrate, mobility directed to a chemoattractant gradient (chemotaxis), ingestion of inert particles and superoxide anion production were analysed. The results show that diet supplementation with NAC plus thioproline increased all macrophage functions studied with the exception of superoxide anion production, which was decreased. These effects were more evident in macrophages from Swiss mice, whereas in BALB/c mice the stimulation of phagocytosis and IL-1beta production was lower and no differences were seen after treatment in adherence and superoxide anion production. These data suggest that immune function can be improved in adult mice by administration of the above thiol compounds, especially in the noninbred strain of OF1-Swiss mice.     

Effects of endotoxic shock in several functions of murine peritoneal macrophages

Gram negative sepsis and septic shock continue to be a major medical problem, with a complex physiopathology and it is associated with high mortality. Although secretion of cytokines such as tumor necrosis factor-alpha by macrophages is the principal host mediator of septic shock, other characteristic functions of macrophages implicated in their phagocytic capacity have not been studied in the process of endotoxic shock. In the present study we have used an intraperitoneal injection of E. coli lipopolysaccharide (LPS) (100 mg/kg) in order to obtain an endotoxic shock model in adult female BALB/c mice. Peritoneal cell suspensions were obtained at several times (2, 4, 12 or 24 h) after injection and the following functions were studied on the peritoneal macrophages: adherence to substrate, mobility (spontaneous and directed or chemotaxis), ingestion of particles and superoxide anion production. The results showed a stimulation of adherence, ingestion and superoxide production as well as a decrease of chemotaxis in the animals injected with LPS. These effects changed with time after LPS injection. Thus, the increase of adherence and the decrease of mobility were higher during the first hours, whereas the increase in ingestion and superoxide production turned larger with time.     

Inmunosenescencia prematura en ratones triple-transgénicos para la enfermedad del Alzheimer

Introduction

A deterioration of the neuroimmunoendocrine network has been observed in Alzheimer's disease (AD). However, the peripheral immune response has hardly been investigated in this pathology. Since some immune function parameters have been established as good markers of the rate of ageing, and can predict longevity, the aim of the present work was to study some of these functions in splenic leucocytes in transgenic mice for AD of different ages.

Material and methods

Young female (4 ± 1 months), adult (9 ± 1 months), and mature (12 ± 1 months) triple-transgenic mice for AD (3 xTgAD) and non-transgenic (NTg) control mice of the same ages were used. The chemotaxis, the anti-tumour activity of «natural killer» (NK) cells and the lymphoproliferative response in the presence of the mitogens concanavalin A and lipopolysaccharide, functions that decrease with age, were determined in splenic leucocytes. In addition, the differences in lifespan between 3 xTgAD and NTg were studied in parallel using other animals, until their death through natural causes.

Results

In 3 xTgAD, with respect to NTg, chemotaxis decreased at all ages studied, whereas in lymphoproliferative response this reduction was shown at 4 months and 9 months. NK activity was diminished only in young 3 xTgAD with respect to NTg. The 3 xTgAD showed a shorter lifespan than the NTg control group.

Conclusions

The 3 xTgAD mice show a premature immunosenescence, which could explain their early mortality. The determination of these immune functions at peripheral level could serve as a marker of the progression of the Alzheimer's disease.     

Modulation of murine macrophage function by N-acetylcysteine in a model of endotoxic shock

In previous studies we have observed changes in several functions of peritoneal macrophages from BALB/c mice with irreversible endotoxic shock caused by intraperitoneal injection of E. coli lipopolysaccharide (LPS) (100 mg/kg), which were associated with a high production of superoxide anion. Since antioxidants, such as N-acetylcysteine (NAC), are free radical scavengers that improve the immune response, in the present work we have studied different functions of peritoneal macrophages from BALB/c mice suffering the endotoxic shock above indicated and administered N-acetylcysteine (150 mg/kg i.p.) at 30 minutes after LPS injection. In the peritoneal macrophages obtained at 2, 4, 12 and 24 h after LPS injection, the following functions were studied: adherence to substrate, mobility, ingestion of particles, and production of superoxide anion and tumour necrosis factor (TNF alpha). The increase in adherence, ingestion and superoxide anion and TNF alpha production shown by macrophages from animals with endotoxic shock was counteracted by NAC injection. Moreover, the survival time of mice with endotoxic shock was increased in the presence of NAC. These data suggest that NAC, administered intraperitoneally, may be useful for the treatment of irreversible endotoxic shock by modulation of the function of macrophages with decreased superoxide anion and TNF alpha production and concomitant increase of survival time.     

Effect of aging on the modulation of macrophage functions by neuropeptides

The existence of a functional connection between the nervous and the immune system is supported by increasing recent evidence. In previous work we have shown that peptides from the nervous system, such as gastrin-releasing peptide (GRP), neuropeptide Y (NPY) and sulfated cholecystokinin octapeptide (CCK-8s), have modulatory effects on the immune functions in adult animals. Since the immunodepression found in aging organisms may be related to changes in the neuroimmune network, the aim of the present work was to study the changes with aging in the effect of CCK-8s, GRP and NPY on peritoneal macrophage functions (adherence to tissues, mobility, ingestion of foreign particles and superoxide anion production) from BALB/c mice of three different ages: adult (24+/-2 weeks old), mature (50+/-2 weeks old) and old (72+/-2 weeks old). The results show that the increase in adherence capacity produced by neuropeptides in cells from adult and mature animals disappears in old mice. The stimulatory effect of GRP and NPY on mobility, ingestion and superoxide production in macrophages from adult mice disappears (GRP) or changes to inhibition (NPY) in cells from old animals. The decrease of these functions caused by CCK-8s in adult or mature animals continues in old mice. These data suggest that the modulation by neuropeptides of the macrophage function changes with the age of animals.     

Effects of selected insecticides on Diadegma insulare (Hymenoptera: Ichneumonidae), a parasitoid of Plutella xylostella (Lepidoptera: Plutellidae)

Effects of eight insecticides on Diadegma insulare (Cresson), a parasitoid of the diamondback moth, Plutella xylostella L., were evaluated under the laboratory conditions. The insecticides were three azadirachtin-based products (Ecozin, Agroneem and Neemix), two Bacillus thuringiensis (Bt) products (Xentari and Crymax), indoxacarb, spinosad, and λ-cyhalothrin. When D. insulare pupae were treated, none of the insecticide treatments except λ-cyhalothrin significantly reduced adult emergence, with 76-90% adults emerged from the treated pupae. In the λ-cyhalothrin treatment, only 10% D. insulare pupae produced adult wasps. Indoxacarb, spinosad, and λ-cyhalothrin caused 100% D. insulare adult mortality in 24 h in Petri dishes sprayed with insecticides in the contact bioassays, and 95.8, 100 and 95.8% adult mortality in 24 h in the ingestion bioassays, respectively. In contrast, all three azadirachtin-based insecticides and the two Bt-insecticides caused only 0-10.4% mortality of D. insulare adults after ingestion. The surviving D. insulare from ingestion treatments with Bt- and azadirachtin-insecticides parasitized 50.8-67.6% of P. xylostella larvae, respectively, compare to 72.1% for the water control. After ingesting indoxacarb, spinosad and λ-cyhalothrin mixed in honey-water, both the females and the males lived significantly shorter than those ingesting Bt- and azadirachtin-insecticides and the non-insecticide honey-water. Effects of leaf residues of indoxacarb, spinosad and λ-cyhalothrin varied significantly. The leaf residues of spinosad had the least effects on D. insulare adults, and 7- and 10-day-old residue only caused 5.6 and 7.4% mortality in 24 h, whereas 10-day-old leaf residues of indoxacarb and λ-cyhalothrin caused 40.7 and 57.4% mortality in 24 h, respectively.     

Ascorbic acid and N-acetylcysteine improve in vitro the function of lymphocytes from mice with endotoxin-induced oxidative stress

Oxidative stress associated with reactive oxygen species (ROS) and cytokines produced by immune cells, which is involved in septic shock caused by endotoxin, can be controlled to a certain degree by antioxidants with free radical scavenging action. N-acetylcysteine (NAC) and ascorbic acid (AA) are ROS scavengers that improve the immune response, and modulate macrophage function in mice with endotoxin-caused oxidative stress. Therefore, we have investigated the in vitro effects of these antioxidants on the functions of lymphocytes from BALB/c mice with lethal endotoxic shock caused by intraperitoneal injection of E. coli lipopolysaccharide (LPS) (100 mg/kg). Adherence to tissues and chemotaxis (the earliest two functions of lymphocytes in the immune response), as well as ROS levels and TNFα production were determined in the presence or absence of NAC or AA (0.001, 0.01, 0.1, 1 and 2.5 mM) in lymphocytes from peritoneum, axillary nodes, spleen and thymus obtained at several times (2, 4, 12 and 24 hours) after LPS injection. Endotoxic shock decreases the chemotaxis of lymphocytes from all the above localizations and increases their adherence, TNFα and ROS production. These changes in lymphocyte function were counteracted by NAC and AA, bringing these functions to values near those of control animals. Our data suggest that lymphocytes are important targets of endotoxins contributing to oxidative stress by septic shock, and that antioxidants can preserve the function of lymphocytes, preventing the homeostatic disturbances caused by endotoxin.     

Ascorbic acid and N-acetylcysteine improve in vitro the function of lymphocytes from mice with endotoxin-induced oxidative stress.

Oxidative stress associated with reactive oxygen species (ROS) and cytokines produced by immune cells, which is involved in septic shock caused by endotoxin, can be controlled to a certain degree by antioxidants with free radical scavenging action. N-acetylcysteine (NAC) and ascorbic acid (AA) are ROS scavengers that improve the immune response, and modulate macrophage function in mice with endotoxin-caused oxidative stress. Therefore, we have investigated the in vitro effects of these antioxidants on the functions of lymphocytes from BALB/c mice with lethal endotoxic shock caused by intraperitoneal injection of E. coli lipopolysaccharide (LPS) (100 mg/kg). Adherence to tissues and chemotaxis (the earliest two functions of lymphocytes in the immune response), as well as ROS levels and TNF alpha production were determined in the presence or absence of NAC or AA (0.001, 0.01, 0.1, 1 and 2.5 mM) in lymphocytes from peritoneum, axillary nodes, spleen and thymus obtained at several times (2, 4, 12 and 24 hours) after LPS injection. Endotoxic shock decreases the chemotaxis of lymphocytes from all the above localizations and increases their adherence, TNF alpha and ROS production. These changes in lymphocyte function were counteracted by NAC and AA, bringing these functions to values near those of control animals. Our data suggest that lymphocytes are important targets of endotoxins contributing to oxidative stress by septic shock, and that antioxidants can preserve the function of lymphocytes, preventing the homeostatic disturbances caused by endotoxin.     

Prostaglandin D2 suppresses human NK cell function via signaling through D prostanoid receptor

NK cells play critical roles in immune responses against tumors or virus infections by generating type 1 cytokine and cytotoxicity responses. In contrast, during type 2 dominant immune responses, such as allergic diseases, activities of NK cells are often impaired. These type 2 immune-mediated diseases have been reported to be closely associated with local production of PGD(2). PGD(2) is an eicosanoid primarily synthesized by mast cells and alveolar macrophages, and it functions through two major receptors, D prostanoid receptor (DP) and chemoattractant receptor-like molecule on the Th2 cell. Within the immune system, PGD(2) binding to DP generally leads to suppression of cellular functions. In the current study, we show that: 1) DP is expressed in human NK cells as detected by mRNA analysis and Western blot; 2) PGD(2) inhibits cytotoxicity, chemotaxis, and type 1 cytokine production of human NK cells via signaling through DP; 3) PGD(2) signaling via DP elevates intracellular cAMP levels and the inhibitory effects on NK cells are cAMP dependent; 4) PGD(2) binding to DP suppresses Ca(2+) mobilization triggered by the cross-linking of the activating receptor, CD16. Together, these data uncover a novel mechanism by which PGD(2) functions through DP to suppress type 1 and cytolytic functions of human NK cells, thus contributing to the promotion of a type 2 immune response.     

Immunosuppressive effects of extracts of helminthic parasites in C57BL mice

and 1986. Immunosuppressive effects of extracts of helminthic parasites in C57BL mice. International Journal for Parasitology 16: 607–615. Crude saline extracts of adult Nematospiroides dubius or Nippostrongylus brasiliensis worms administered with an i.p. immunization of ovalbumin (OA) in Al(OH)₃ depressed primary and secondary IgG responses, delayed-type hypersensitivity and in vitro splenic lymphoproliferative responses to the OA. The suppressive agent was trypsin-sensitive and was also present in larval extracts of the above parasites at levels proportional to their protein contents. Residual gut contents from infected mice caused no suppression. The extracts had little effect on the uptake of ¹²⁵I-PVP from the peritoneum or on peritoneal macrophage activation as assessed by cell numbers, lymphocystostatic potential and acid phosphatase activity. When present in cultures of normal spleen cells, the extracts impaired mitogen-induced lymphoproliferation if added with or before the mitogen. Possible roles for suppressor T cells, suppressive peritoneal or splenic macrophages and direct inhibition of clonal expansion in the suppression of the responses to OA are discussed.     

Mejoría de la inmunidad y la esperanza de vida en ratones maduros,genéticamente deficientes en la síntesis de catecolaminas,tras convivir con controles durante dos meses

IntroductionMice hemizygous in tyrosine hydroxylase (TH-HZ), the limiting enzyme in catecholamine synthesis, show premature immunosenescence, which in females is associated with a shorter lifespan than the corresponding controls (WT). The coexistence of TH-Hz with WT improves the immune function in both males and females in adulthood.ObjectiveTo test whether cohabitation for two months of mature male TH-HZ with WT improves the immune function of the former and whether this impacts the lifespan.Material and methodsMature male ICR-CD1 mice (13 ± 1 months) TH-HZ coexisted with WT (2:4 ratio in each cage) for two months. Peritoneal leukocytes were extracted from all animals at baseline, one month, and two months after cohabitation, and macrophage phagocytic capacity, macrophage and lymphocyte chemotaxis, natural killer (NK) antitumor activity, and lymphoproliferative capacity in response to the mitogens concanavalin A and lipopolysaccharide (LPS) were assessed. The animals were maintained under these conditions until their natural death.ResultsThe TH-HZ, which start, in general, with lower values than the WT in the immune functions studied, improved them after two months of cohabitation, becoming similar to those of the controls. This improvement was already observed in NK activity after one month of cohabitation.The TH-HZ presented lower mean longevity than WT, but when they cohabited with WT, it was similar to the latter.ConclusionThe coexistence of TH-HZ male mice with WT mice for two months at mature age improves these genetically modified animals’ immune response and longevity.     

N-acetylcysteine Protects Mice from Lethal Endotoxemia by Regulating the Redox State of Immune Cells

The excessive production of reactive oxygen species (ROS) associated with inflammation leads to oxidative stress, which is involved with the high mortality from several diseases such as endotoxic shock and can be controlled to a certain degree by antioxidants. The immune cells use ROS in order to support their functions and, therefore, need adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive ROS production. In the present work, the effect of the administration of the antioxidant N-acetylcysteine (NAC) on the redox state of peritoneal macrophages and lymphocytes from mice with lethal endotoxic shock (100 mg/kg i.p. of lipopolysaccharide, LPS), was studied. In both types of immune cells at 0, 2, 4, 12 and 24 h after LPS injection, an increase of ROS, of the proinflammatory cytokine tumor necrosis factor alpha (TNFα), the lipid peroxidation (malonaldehyde levels, MDA), inducible nitric oxide synthase (iNOS) expression and the oxidized/reduced glutathione (GSSG/GSH) ratio, as well as a decrease of enzymatic antioxidant defenses, such as superoxide dismutase (SOD) and catalase (CAT) activity, was observed. The injection of NAC (150 mg/kg i.p. at 30 min after LPS injection) decreased the ROS, the TNFα the MDA levels, iNOS expression and the GSSG/GSH ratio, and increased the antioxidant defenses in both macrophages and lymphocytes. Moreover, the NAC treatment prevented the activation of nuclear translocation of the nuclear factor κB (NF-κB), which regulates ROS, inflammatory cytokines and antioxidant levels. Our present results provide evidence that both cell types have a relevant role in the pathogenesis of endotoxic shock, and that NAC, by improving the redox state of these immune cells, could increase mouse survival. Thus, antioxidants could offer an alternative treatment of human endotoxic shock.     

Possible mechanism of the preventive effect of BCG against diabetes mellitus in NOD mouse. I. Generation of suppressor macrophages in spleen cells of BCG-vaccinated mice.

With the aim of clarifying the mechanism of the suppressive action of BCG against insulitis and overt diabetes in NOD mice, we studied the effects of BCG on spleen cell populations and on the in vitro immune responses of spleen cells. The spleen cells of BCG-vaccinated mice showed much lower responsiveness to various mitogens such as Con A, PHA, PWM, and LPS than those of saline-treated mice. Low responsiveness to alloantigens was also observed. Flow cytometric analysis of the spleen cells revealed that Mac-1+ and Mac-2+ cells had increased while T and B cells had decreased in the BCG-vaccinated mice compared with the saline-treated mice at the time when the maximum level of inhibition of mitogen responses of BCG-vaccinated mice was observed. This suggests that the decreased in vitro immune response was due to the increase in macrophages which suppress lymphocyte functions. Support for this interpretation comes from the following two findings: (1) the restoration of mitogen responses of spleen cells when macrophages were eliminated by plastic adhesion or FACS sorting and (2) resuppression of PHA and Con A responses of plastic-nonadherent spleen cells by addition of adherent cells or flow cytometrically sorted Mac-1+ cells obtained from BCG-vaccinated mice. These results indicate the generation of suppressor macrophages after BCG vaccination and suggest that these macrophages prevent the autoimmune pathogenesis leading to diabetes in NOD mice.     

Impaired immune responses in the lungs of aged mice following influenza infection

Background

Each year, influenza virus infection causes severe morbidity and mortality, particularly in the most susceptible groups including children, the elderly (>65 years-old) and people with chronic respiratory diseases. Among the several factors that contribute to the increased susceptibility in elderly populations are the higher prevalence of chronic diseases (e.g. diabetes) and the senescence of the immune system.

Methods

In this study, aged and adult mice were infected with sublethal doses of influenza virus (A/Puerto Rico/8/1934). Differences in weight loss, morbidity, virus titer and the kinetics of lung infiltration with cells of the innate and adaptive immune responses were analyzed. Additionally, the main cytokines and chemokines produced by these cells were also assayed.

Results

Compared to adult mice, aged mice had higher morbidity, lost weight more rapidly, and recovered more slowly from infection. There was a delay in the accumulation of granulocytic cells and conventional dendritic cells (cDCs), but not macrophages in the lungs of aged mice compared to adult animals. The delayed infiltration kinetics of APCs in aged animals correlated with alteration in their activation (CD40 expression), which also correlated with a delayed detection of cytokines and chemokines in lung homogenates. This was associated with retarded lung infiltration by natural killer (NK), CD4⁺ and CD8⁺ T-cells. Furthermore, the percentage of activated (CD69+) influenza-specific and IL-2 producer CD8+ T-cells was higher in adult mice compared to aged ones. Additionally, activation (CD69+) of adult B-cells was earlier and correlated with a quicker development of neutralizing antibodies in adult animals.

Conclusion

Overall, alterations in APC priming and activation lead to delayed production of cytokines and chemokines in the lungs that ultimately affected the infiltration of immune cells following influenza infection. This resulted in delayed activation of the adaptive immune response and subsequent delay in clearance of virus and prolonged illness in aged animals. Since the elderly are the fastest growing segment of the population in developed countries, a better understanding of the changes that occur in the immune system during the aging process is a priority for the development of new vaccines and adjuvants to improve the immune responses in this population.     

N-acetylcysteine protects mice from lethal endotoxemia by regulating the redox state of immune cells

The excessive production of reactive oxygen species (ROS) associated with inflammation leads to oxidative stress, which is involved with the high mortality from several diseases such as endotoxic shock and can be controlled to a certain degree by antioxidants. The immune cells use ROS in order to support their functions and, therefore, need adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive ROS production. In the present work, the effect of the administration of the antioxidant N-acetylcysteine (NAC) on the redox state of peritoneal macrophages and lymphocytes from mice with lethal endotoxic shock (100 mg/kg i.p. of lipopolysaccharide, LPS), was studied. In both types of immune cells at 0, 2, 4, 12 and 24 h after LPS injection, an increase of ROS, of the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha), the lipid peroxidation (malonaldehyde levels, MDA), inducible nitric oxide synthase (iNOS) expression and the oxidized/reduced glutathione (GSSG/GSH) ratio, as well as a decrease of enzymatic antioxidant defenses, such as superoxide dismutase (SOD) and catalase (CAT) activity, was observed. The injection of NAC (150 mg/kg i.p. at 30 min after LPS injection) decreased the ROS, the TNFalpha the MDA levels, iNOS expression and the GSSG/GSH ratio, and increased the antioxidant defenses in both macrophages and lymphocytes. Moreover, the NAC treatment prevented the activation of nuclear translocation of the nuclear factor kappaB (NF-kappaB), which regulates ROS, inflammatory cytokines and antioxidant levels. Our present results provide evidence that both cell types have a relevant role in the pathogenesis of endotoxic shock, and that NAC, by improving the redox state of these immune cells, could increase mouse survival. Thus, antioxidants could offer an alternative treatment of human endotoxic shock.