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1.
We study the ameliorative potential of dimetylthiourea (DMTU), an OH• radical trapper and N-acetylcysteine (NAC), a glutathione precursor/H2O2 scavenger against titanium dioxide nanoparticles (TiO2-NPs) and multi-walled carbon nanotubes (MWCNTs) induced cyto-genotoxicity in cultured human lung cancer cells-A549. Cytogenotoxicity was induced by exposing the cells to selected concentrations (10 and 50 µg/ml) of either of TiO2-NPs or MWCNTs for 24 h. Anti-cytogenotoxicity effects of DMTU and NAC were studied in two groups, i.e., treatment of 30 minutes prior to toxic insult (short term exposure), while the other group received DMTU and NAC treatment during nanoparticles exposure, i.e., 24 h (long term exposure). Investigations were carried out for cell viability, generation of reactive oxygen species (ROS), micronuclei (MN), and expression of markers of oxidative stress (HSP27, CYP2E1), genotoxicity (P53) and CYP2E1 dependent n- nitrosodimethylamine-demethylase (NDMA-d) activity. In general, the treatment of both DMTU and NAC was found to be effective significantly against TiO2-NPs and MWCNTs induced cytogenotoxicity in A549 cells. Long-term treatment of DMTU and NAC during toxic insults has shown better prevention than short-term pretreatment. Although, cells responded significantly to both DMTU and NAC, but responses were chemical specific. In part, TiO2-NPs induced toxic responses were mediated through OH• radicals generation and reduction in the antioxidant defense system. While in the case of MWCNTs, adverse effects were primarily due to altering/hampering the enzymatic antioxidant system. Data indicate the applicability of human lung cancer cells-A549 as a pre-screening tool to identify the target specific prophylactic and therapeutic potential of drugs candidate molecules against nanoparticles induced cellular damages. 相似文献
2.
LINE‐1 hypomethylation induced by reactive oxygen species is mediated via depletion of S‐adenosylmethionine
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Chiraphat Kloypan Monpicha Srisa‐art Apiwat Mutirangura Chanchai Boonla 《Cell biochemistry and function》2015,33(6):375-384
Whether long interspersed nuclear element‐1 (LINE‐1) hypomethylation induced by reactive oxygen species (ROS) was mediated through the depletion of S‐adenosylmethionine (SAM) was investigated. Bladder cancer (UM‐UC‐3 and TCCSUP) and human kidney (HK‐2) cell lines were exposed to 20 μM H2O2 for 72 h to induce oxidative stress. Level of LINE‐1 methylation, SAM and homocysteine (Hcy) was measured in the H2O2‐exposed cells. Effects of α‐tocopheryl acetate (TA), N‐acetylcysteine (NAC), methionine, SAM and folic acid on oxidative stress and LINE‐1 methylation in the H2O2‐treated cells were explored. Viabilities of cells treated with H2O2 were not significantly changed. Intracellular ROS production and protein carbonyl content were significantly increased, but LINE‐1 methylation was significantly decreased in the H2O2‐treated cells. LINE‐1 methylation was restored by TA, NAC, methionine, SAM and folic acid. SAM level in H2O2‐treated cells was significantly decreased, while total glutathione was significantly increased. SAM level in H2O2‐treated cells was restored by NAC, methionine, SAM and folic acid; while, total glutathione level was normalized by TA and NAC. Hcy was significantly decreased in the H2O2‐treated cells and subsequently restored by NAC. In conclusion, in bladder cancer and normal kidney cells exposed to H2O2, SAM and Hcy were decreased, but total glutathione was increased. Treatments with antioxidants (TA and NAC) and one‐carbon metabolites (SAM, methionine and folic acid) restored these changes. This pioneer finding suggests that exposure of cells to ROS activates glutathione synthesis via the transsulfuration pathway leading to deficiency of Hcy, which consequently causes SAM depletion and eventual hypomethylation of LINE‐1. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
DMSO differentiated U937 cells responded to 10−6 M LTD4, LTB4 and FMLP with an increase in both InsP formation and [Ca2+]i. FMLP caused a greater rise in InsPs than either LTD4 or LTB4, which were equivalent. LTD4, however, caused a greater increase in [Ca2+]i than LTB4 (4-fold) or FMLP. The FMLP [Ca2+]i and InsP responses were abolished by pertussis toxin (100 ng/ml for 4 h) but were unaffected by PMA (10−7 M for 3 min). In contrast, the LTD4 [Ca2+]i and InsP responses were reduced by only 50% by pertussis toxin, whilst PMA reduced the [Ca2+]i and InsP responses to LTD4 by 75 and 30%, respectively. These results suggest that mechanisms additional to InsP formation exist for mediating LTD4 evoked increases in [Ca2+]i. 相似文献
4.
5.
Testicular cancer is a very common cancer in males aged 15–44 years. Bleomycin is used in chemotherapy regimens in the treatment of patients having testicular germ-cell tumor. Bleomycin generates oxygen radicals, induces oxidative cleavage of DNA strand and induces apoptosis in cancer cells. There is no study in the literature investigating effects of N-Acetyl-l-Cysteine (NAC) on bleomycin-induced oxidative stress in testicular germ cell tumors. For this reason, we studied effects of NAC on oxidative stress produced in wild-type NTera-2 and p53-mutant NCCIT testis cancer cells incubated with bleomycin and compared the results with H2O2 which directly produces oxidative stress. We determined protein carbonyl content, thiobarbituric acid reactive substances (TBARS), glutathione (GSH), 8-isoprostane, lipid hydroperoxide levels and total antioxidant capacity in both testicular cancer cells. Bleomycin and H2O2 significantly increased 8-isoprostane, TBARS, protein carbonyl and lipid hydroperoxide levels in NTera-2 and NCCIT cells. Bleomycin and H2O2 significantly decreased antioxidant capacity and GSH levels in both cell lines. Co-incubation with NAC significantly decreased lipid hydroperoxide, 8-isoprostane, protein carbonyl content and TBARS levels increased by bleomycin and H2O2. NAC enhanced GSH levels and antioxidant capacity in the NTera-2 and NCCIT cells. It can be concluded that NAC diminishes oxidative stress in human testicular cancer cells induced by bleomycin and H2O2. 相似文献
6.
Steven L. Kunkel Kip Kaercher Micheal Plewa Joseph C. Fantone Peter A. Ward 《Prostaglandins & other lipid mediators》1982,24(6):789-799
Mononuclear phagocytes are knwon to play a key role in various phlogistic reactions by synthesizing and releasing products that may potentiate or inhibit inflammatory processes. The expression of these products appears to be dependent on the source of the macrophage population as well as the stimulus employed. We have studied superoxide anion (O2−) production as well as the generation of PGE2, PGF2α, and TXB2 from resident, oil-elicited and thiogylcollate-induced peritoneal macrophages in mice in the presence and absence of chemotactic peptides. Production of O2−, occurred only in elicited macrophages stimulated with high concentrations of FMLP or C5a; resident cells stimulated with either of the chemotactic peptides were completely unresponsive. Although resident peritoneal macrophages incubated with chemotactic peptides did not generate O2−, these cells did secrete significant levels of PGE2, PGF2α, and TXB2 in response to C5a. FMLP had no stimulatory effect. Elicited macrophages generated increased levels of PGE2 and PGF2α when incubated with C5a. However, production of TXB2 was not stimulated. FMLP was inactive in stimulating PGE2, PGF2α, and TXB2 in all types of macrophages studied. These studies indicate a heterogeneity in the production of inflammatory mediators from various macrophage populations in response to chemotactic factors. 相似文献
7.
Aysegul Cort Mujgan Timur Evrim Dursun Ertan Kucuksayan Mutay Aslan Tomris Ozben 《Journal of physiology and biochemistry》2012,68(4):555-562
Oxidative stress has been shown to induce apoptosis in cancer cells. Therefore, one might suspect that antioxidants may inhibit reactive oxygen species (ROS) and prevent apoptosis of cancer cells. No study has been carried out so far to elucidate the effects of N-acetylcysteine (NAC) on bleomycin-induced apoptosis in human testicular cancer (NCCIT) cells. We investigated the molecular mechanisms of apoptosis induced by bleomycin and the effect of NAC in NCCIT cells. We compared the effects of bleomycin on apoptosis with H2O2 which directly produces ROS. Strong antioxidant NAC was evaluated alone and in combination with bleomycin or H2O2 in germ cell tumor-derived NCCIT cell line (embryonal carcinoma, being the nonseminomatous stem cell component). We determined the cytotoxic effect of bleomycin and H2O2 on NCCIT cells and measured apoptosis markers such as caspase-3, caspase-8, and caspase-9 activities and Bcl-2, Bax, and cytochrome c (Cyt-c) levels in NCCIT cells incubated with bleomycin, H2O2, and/or NAC. We found half of the lethal dose (LD50) of bleomycin on NCCIT cell viability as 120???g/ml after incubation for 72?h. Incubation with bleomycin (LD50) induced increases in caspase-3, caspase-8, and caspase-9 activities and Cyt-c and Bax protein levels and a decrease in Bcl-2 level. Co-incubation of NCCIT cells with bleomycin and 10?mM NAC abolished bleomycin-induced increases in caspase-3 and caspase-9 activities, Bax, and Cyt-c levels and bleomycin-induced decrease in Bcl-2 level. Our results indicate that bleomycin induces apoptosis in NICCT cells and that NAC diminishes bleomycin-induced apoptosis via inhibiting the mitochondrial pathway. We conclude that NAC has negative effects on bleomycin-induced apoptosis in NICCT cells and causes resistance to apoptosis, which is not a desirable effect in the fight against cancer. 相似文献
8.
《BBA》1985,809(3):345-350
Reversible photoreduction of pheophytin (Pheo) accompanied by a decrease of chlorophyll-fluorescence yield is observed in subchloroplast oxygen-evolving preparations of Photosystem II (PS II) under anaerobic conditions. This photoreaction is activated at addition of CCCP, inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and reactivated upon subsequent addition of ascorbate. Benzyl viologen as well as methyl viologen accelerates dark oxidation of reduced pheophytin, indicating that they are able to accept an electron from Pheo⨪. The data on both the photoreduction of pheophytin in the absence of exogenous reductants - when electron donation to reaction centers of PS II occurs only from water - and the inhibition of this photoreaction by DCMU show that the pheophytin photoreduction is sensitized by reaction centers of PS II, and it probably occurs as a result of electron donation from the water-splitting system being in the sate S3 to P⨥-680Pheo⨪Q−, producing the long-lived state S0 P-680Pheo⨪Q− and O2. Photoreduction of pheophytin in the presence of ascorbate (and dithionite) evidently occurs as a result of donation of its electrons to P⨥-680Pheo⨪Q− by means of the S-states of the water-oxidizing system. It is shown that the photoinduced decrease of fluorescence in chloroplasts under anaerobic conditions is due to two processes: photoreduction of pheophytin in Photosystem II and photooxidation of Q− by Photosystem I. It is suggested that photoreduction of pheophytin takes also place under aerobic conditions when Q is reduced. It may contribute to the P−S fluorescence decrease during fluorescence induction in leaves. 相似文献
9.
Escherichia coli cells are inactivated by the products of the reaction between dialuric acid and oxygen, of which the primary product is Superoxide. The rate of inactivation is decreased by Superoxide dismutase, by catalase, and by EDTA, whereas it is increased by addition of cupric ions or hydrogen peroxide. It is concluded that a toxic product is formed in a reaction involving Superoxide, hydrogen peroxide, and metal ions, which might be the Haber-Weiss reaction, O2? + H2O2 → OH + OH? + O2. In radiation chemical experiments it is shown that this reaction does not occur in the absence of metal ions. 相似文献
10.
The scavenging of superoxide radical by manganous complexes: in vitro 总被引:22,自引:0,他引:22
Dialyzable manganese has been shown to be present in millimolar concentrations within cells of Lactobacillus plantarum and related lactic acid bacteria. This unusual accumulation of Mn appears to serve the same function as Superoxide dismutase (SOD), conferring hyperbaric oxygen and Superoxide tolerance on these SOD-free organisms. The form of the Mn in the lactic acid bacteria and the mechanisms whereby it protects the cell from oxygen damage are unknown. This report examines the mechanisms by which Mn catalytically scavenges O2?, both in the xanthine oxidase/cytochrome c SOD assay and in a number of in vitro systems relevant to the in vivo situation. In all the reaction mixtures examined, Mn(II) is first oxidized by O2? to Mn(III), and H2O2 is formed. In pyrophosphate buffer the Mn(III) thus formed is re-reduced to Mn(II) by a second O2?, making the reaction a true metal-catalyzed dismutation like that catalyzed by SOD. Alternatively, if the reaction takes place in orthophosphate or a number of other buffers, the Mn(III) is preferentially reduced largely by reductants other than O2?, such as thiols, urate, hydroquinone, or H2O2. H2O2, a common product of the lactic acid bacteria, reacted rapidly with Mn(III) to form O2, apparently without intermediate O2 release. Free hexaquo Mn(II) ions were shown by electron spin resonance spectroscopy and activity assays in noncomplexing buffers to be poorly reactive with O2?. In contrast, Mn(II) formed complexes having a high catalytic activity in scavenging O2? with a number of organic acids, including malate, pyruvate, propionate, succinate, and lactate, with the Mn-lactate complex showing the greatest activity. 相似文献
11.
Yoshihiro Ojima Mark Thompson Duncan Retno Wahyu Nurhayati Masahito Taya William Martin Miller 《Experimental cell research》2013
The human myelogenous cell line, K562 has been extensively used as a model for the study of megakaryocytic (MK) differentiation, which could be achieved by exposure to phorbol 12-myristate 13-acetate (PMA). In this study, real-time PCR analysis revealed that the expression of catalase (cat) was significantly repressed during MK differentiation of K562 cells induced by PMA. In addition, PMA increased the intracellular reactive oxygen species (ROS) concentration, suggesting that ROS was a key factor for PMA-induced differentiation. PMA-differentiated K562 cells were exposed to hydrogen peroxide (H2O2) to clarify the function of ROS during MK differentiation. Interestingly, the percentage of high-ploidy (DNA content >4N) cells with H2O2 was 34.8±2.3% at day 9, and was 70% larger than that without H2O2 (21.5±0.8%). Further, H2O2 addition during the first 3 days of PMA-induced MK differentiation had the greatest effect on polyploidization. In an effort to elucidate the mechanisms of enhanced polyploidization by H2O2, the BrdU assay clearly indicated that H2O2 suppressed the division of 4N cells into 2N cells, followed by the increased polyploidization of K562 cells. These findings suggest that the enhancement in polyploidization mediated by H2O2 is due to synergistic inhibition of cytokinesis with PMA. Although H2O2 did not increase ploidy during the MK differentiation of primary cells, we clearly observed that cat expression was repressed in both immature and mature primary MK cells, and that treatment with the antioxidant N-acetylcysteine effectively blocked and/or delayed the polyploidization of immature MK cells. Together, these findings suggest that MK cells are more sensitive to ROS levels during earlier stages of maturation. 相似文献
12.
Kinetic analysis of superoxide anion production by activated and resident murine peritoneal macrophages 总被引:2,自引:0,他引:2
Using a continuous spectrophotometric assay, we have monitored the formation of superoxide anion (O2?) by activated and resident murine peritoneal macrophages. Macrophages elicited by injection with Corynebacterium parvum, as well as resident macrophages from untreated mice, were kept in suspension culture overnight to eliminate short-lived, contaminating neutrophils. Cytochemical analysis of the cultured macrophages disclosed that essentially all of the activated macrophages reduced nitroblue tetrazolium (NBT) dye vigorously. In contrast, only 18% of the resident macrophages demonstrated vigorous NBT reduction; the remainder of the resident macrophages reduced NBT very weakly. Kinetic analysis of macrophage O2? formation revealed that activated macrophages exposed to phorbol myristate acetate (PMA) produced O2? at a 13-fold greater maximum rate than resident macrophages. The decline in the rate of O2? production with time by activated macrophages was also greater than that of resident macrophages. The data indicate that the greater O2? production by activated macrophage populations is due to (i) the presence of an increased percentage of macrophages that respond to PMA with vigorous O2? production, and (ii) an increased maximum rate of O2? formation by these macrophages. 相似文献
13.
Wenzel U Nickel A Daniel H 《Apoptosis : an international journal on programmed cell death》2005,10(2):359-368
The antioxidant -lipoic acid (ALA) has been shown to affect a variety of biological processes associated with oxidative stress including cancer. We determined in HT-29 human colon cancer cells whether ALA is able to affect apoptosis, as an important parameter disregulated in tumour development. Exposure of cells to ALA or its reduced form dihydrolipoic acid (DHLA) for 24 h dose dependently increased caspase-3-like activity and was associated with DNA-fragmentation. DHLA but not ALA was able to scavenge cytosolic O2–. in HT-29 cells whereas both compounds increased O2– .-generation inside mitochondria. Increased mitochondrial O2– .-production was preceded by an increased influx of lactate or pyruvate into mitochondria and resulted in the down-regulation of the anti-apoptotic protein bcl-XL. Mitochondrial O2–.-generation and apoptosis induced by ALA and DHLA could be prevented by the O2– .-scavenger benzoquinone. Moreover, when the lactate/pyruvate transporter was inhibited by 5-nitro-2-(3-phenylpropylamino) benzoate, ALA- and DHLA-induced mitochondrial ROS-production and apoptosis were blocked. In contrast to HT-29 cells, no apoptosis was observed in non-transformed human colonocytes in response to ALA or DHLA addition. In conclusion, our study provides evidence that ALA and DHLA can effectively induce apoptosis in human colon cancer cells by a prooxidant mechanism that is initiated by an increased uptake of oxidizable substrates into mitochondria. 相似文献
14.
Intact and pure parenchymal and nonparenchymal cells were isolated from rat liver. The activities of Superoxide dismutase in these cell types were determined by two different methods. With both methods the specific activity of this enzyme is 1.5 times higher in parenchymal than in nonparenchymal liver cells. It can be calculated that about 7% of the total rat liver Superoxide dismutase activity is localized in the nonparenchymal liver cells. Electrophoresis on polyacrylamide gels indicates that the isolated parenchymal cells contain both cytosolic and mitochondrial isoenzymes, whereas with nonparenchymal cells only the cytosolic enzyme could be detected. The mitochondrial band observed in isolated parenchymal cells is absent in the original total liver homogenate. This isoenzyme seems to be activated during the parenchymal cell isolation procedure. Isoelectrofocusing indicates that the cytosolic Superoxide dismutase consists in four different isoelectric forms in both parenchymal and nonparenchymal cells. With the mitochondrial isoenzyme two bands are obtained. The possibility that O2? is an important intermediate in H2O2 formation in nonparenchymal liver cells is discussed. In this respect, Superoxide dismutase might not only protect the cell against a toxic reagent as O2t-, but might also help to regulate the level of the important antimicrobial agent, H2O2. 相似文献
15.
《BBA》1986,849(1):150-161
Flash-induced absorption changes at 450 nm were investigated in isolated chromatophores of Rhodopseudomonas sphaeroides and Rhodospirillum rubrum non-sulfur purple bacteria to follow the redox changes of the semiquinone species of the secondary quinone acceptor of the photosynthetic reaction center. Excitation of a dark-adapted chromatophore suspension by a series of successive flashes in the presence of electron donors capable of rapidly reducing the photooxidized reaction-center pigment causes the formation of a stable semiquinone species (Q⨪B) with a lifetime which is shown to be proportional to the amount of the oxidized redox mediator in the incubation medium. It is shown that the disappearance of the flash-induced absorption changes at 450 nm on lowering the ambient redox potential (Eh) to 200–300 mV is the result of increasing the lifetime of Q⨪B, as the amount of the oxidized mediator diminishes; consequently, in these circumstances, the 2–5 min dark interval between the flash cycles appears insufficient for Q⨪B recovery. After the addition of redox mediators with a low midpoint potential, acting as an oxidant for Q⨪B, the flash-induced redox changes of Q⨪B were observed at low Eh values unless Eh reached a value at which QB underwent reduction at equilibrium to form QBH2. The data provide evidence that reaction centers with a fully oxidized secondary acceptor can donate electrons to the cyclic electron-transport chain only after two turnovers, leading to the formation of the doubly reduced ubiquinone species (QBH2) of the secondary acceptor. 相似文献
16.
To gain further insight into yeast acetic acid-induced programmed cell death (AA-PCD) we analyzed the effects of the antioxidant N-acetyl-l-cysteine (NAC) on cell viability, hydrogen peroxide (H2O2) production, DNA fragmentation, cytochrome c (cyt c) release and caspase-like activation in wild type (wt) and metacaspase and/or cyt c-lacking cells. We found that NAC prevents AA-PCD in wt cells, by scavenging H2O2 and by inhibiting both cyt c release and caspase-like activation. This shows the occurrence of a reactive oxygen species (ROS)-dependent AA-PCD. Contrarily no NAC dependent change in AA-PCD of mutant cells was detectable, showing that a ROS-independent AA-PCD can also occur. 相似文献
17.
Superoxide (O2?) is a primary agent of intracellular oxidative stress. Genetic studies in many organisms have confirmed that excess O2? disrupts metabolism, but to date only a small family of [4Fe‐4S] dehydratases have been identified as direct targets. This investigation reveals that in Escherichia coli O2? also poisons a broader cohort of non‐redox enzymes that employ ferrous iron atoms as catalytic cofactors. These enzymes were inactivated by O2? both in vitro and in vivo. Although the enzymes are known targets of hydrogen peroxide, the outcome with O2? differs substantially. When purified enzymes were damaged by O2? in vitro, activity could be completely restored by iron addition, indicating that the O2? treatment generated an apoprotein without damaging the protein polypeptide. Superoxide stress inside cells caused the progressive mismetallation of these enzymes with zinc, which confers little activity. When O2? stress was terminated, cells gradually restored activity by extracting zinc from the proteins. The overloading of cells with zinc caused mismetallation even without O2? stress. These results support a model in which O2? repeatedly excises iron from these enzymes, allowing zinc to compete with iron for remetallation of their apoprotein forms. This action substantially expands the physiological imprint of O2? stress. 相似文献
18.
Yongqing Hou Lei Wang Dan Yi Binying Ding Zhenguo Yang Jiao Li Xing Chen Yinsheng Qiu Guoyao Wu 《Amino acids》2013,45(3):513-522
This study determined whether N-acetylcysteine (NAC) could affect intestinal redox status, proinflammatory cytokines, epidermal growth factor (EGF), EGF receptor (EGFR), Toll-like receptor-4 (TLR4), and aquaporin-8 in a lipopolysaccharide (LPS)-challenged piglet model. Eighteen piglets (35-day-old) were randomly allocated into one of the three treatments (control, LPS and NAC). The control and LPS groups were fed a basal diet, and the NAC group received the basal diet +500 mg/kg NAC. On days 10, 13, and 20 of the trial, the LPS- and NAC-treated piglets received intraperitoneal administration of LPS (100 μg/kg BW), whereas the control group received the same volume of saline. On days 10 and 20, venous blood samples were obtained at 3 h post LPS or saline injection. On day 21 of the trial, piglets were killed to obtain the intestinal mucosa for analysis. Compared with the control group, LPS challenge reduced (P < 0.05) the activities of superoxide dismutase, catalase, and glutathione peroxidase in jejunal mucosae, while increasing (P < 0.05) the concentrations of malondialdehyde, H2O2, O2 ·? and the ratio of oxidized to reduced glutathione in jejunal mucosae, and concentrations of TNF-α, cortisol, interleukin-6, and prostaglandin E2 in both plasma and intestinal mucosae. These adverse effects of LPS were attenuated (P < 0.05) by NAC supplementation. Moreover, NAC prevented LPS-induced increases in abundances of intestinal HSP70 and NF-κB p65 proteins and TLR4 mRNA. NAC supplementation enhanced plasma EGF concentration and intestinal EGFR mRNA levels. Collectively, these results indicate that dietary NAC supplementation alleviates LPS-induced intestinal inflammation via regulating redox, EGF, and TLR4 signaling. 相似文献
19.
20.
Comparison of airway and blood eosinophil function after in vivo antigen challenge. 总被引:12,自引:0,他引:12
J B Sedgwick W J Calhoun R F Vrtis M E Bates P K McAllister W W Busse 《Journal of immunology (Baltimore, Md. : 1950)》1992,149(11):3710-3718
Eosinophils (EOS) are important effector cells in allergic diseases and asthma. However, functional characteristics of the EOS have been derived primarily from studies of blood cells, and it is unlikely that such assessments reflect events occurring in tissues or airways. To establish more precisely the function of airway EOS, segmental Ag challenge was used to elicit and isolate large numbers of these cells. Airway, as well as blood, EOS were isolated from allergic patients 48 h after segmental Ag challenge. Both blood and bronchoalveolar lavage (BAL) EOS were fractionated over Percoll density gradients; by using this protocol, three density-distinct populations of pure (>90%) EOS were obtained from BAL fluid (1.100, 1.095, and 1.090 g/ml) and one from blood (1.100 g/ml). The functions of these various populations were compared by measuring superoxide generation, adherence to collagen and endothelial cell monolayers, cell surface receptors, and in vitro survival. BAL EOS of all three densities had greater superoxide generation and adherence with FMLP activation than did corresponding blood EOS. In contrast, blood and airway EOS responded similarly to PMA. BAL EOS also had increased expression of CD11b/CD18 and HLA-DR. The intracellular calcium concentration ([Ca2+]i) was measured with the fluorescent marker indo-1/acetoxymethyl ester. FMLP caused a greater and more sustained increase in [Ca2+]i with BAL than blood EOS. EGTA blocked the sustained component of the [Ca2+]i response to FMLP. Our findings indicate that BAL EOS have an enhanced [Ca2+]i response to activation that may contribute to their functional up-regulation. 相似文献