Biomedical subjects

Daniel M Lewis

Publications and source records attributed to Daniel M Lewis.

At least 19 recordsLinked to original sources

PubMed2006

The development of species-specific immunodiagnostics for Stachybotrys chartarum: the role of cross-reactivity.

Mold contamination and exposure to fungi in indoor environments has been associated with various adverse health effects but little is known about the significance of individual fungal species in the initiation or exacerbation of such effects. Using Stachybotrys chartarum as a model fungus we sought to demonstrate that monoclonal antibodies (mAbs) can provide species-specific diagnostic reagents and also be used to investigate immunological cross-reactivity patterns among fungi. Mice were immunized with S. chartarum spore walls and monoclonal antibodies were screened against 60 fungal species and 24 different isolates of S. chartarum using an indirect ELISA. One species-specific mAb (IgG(1)) reacted only with spore preparations but not mycelium of S. chartarum or propagules of any other fungus. Five cross-reactive mAbs (IgM) documented extensive cross-reactivity among nine related Stachybotrys species and several non-related genera including several species of Cladosporium, Memnoniella, Myrothecium and Trichoderma. We also found that the ELISA reactivity for cross-reactive antigens and different isolates of S. chartarum differed considerably for normalized total amounts of mycelial antigen. We demonstrate that mAbs and immunoassays have the potential to detect S. chartarum species-specifically. The observed reactivity patterns with cross-reactive mAbs suggest that several fungi may share common antigens and that the majority of antigens are expressed by spores and mycelia. The observed cross-reactivity patterns need to be considered for accurate interpretations of environmental and serological analyses.

Animals↗

PubMed2006

History and results of the two inter-laboratory round robin endotoxin assay studies on cotton dust.

BACKGROUND: In the US cotton industry, airborne cotton dust levels are regulated, and other countries are moving to specify safety limits for airborne endotoxins. There is concern about potential respiratory health hazards associated with agricultural and other organic dusts. In laboratories, ranking which samples have high and low levels of endotoxin is usually in good agreement between laboratories. When different laboratories assay identical samples, the levels differ. The objective of this research was to evaluate the intra- and inter-laboratory variability for 13 laboratories measuring endotoxin in cotton dust. METHOD: Two inter-laboratory round robin endotoxin assay studies were conducted using cotton dust. In the first round robin, each laboratory used their normal in-house assay method and then used a common extraction protocol. In the second round robin, a common extraction protocol and endotoxin assay kit was used. RESULTS: The intra-laboratory results had small variations but inter-laboratory results had very high variations. The inter-laboratory results using a common extraction protocol showed reduced differences. Using the same extraction protocol and endotoxin assay kit, the intra-laboratory variation was small and inter-laboratory variation was reduced but not enough for inter-laboratory agreement. Most of the laboratories were able to discern between the high and low endotoxin concentration dusts. CONCLUSIONS: Standardization has reduced the differences in results between laboratories and possibly further standardization may bring closer inter-laboratory agreement.

Air Microbiology↗

PubMed2004

Effect of diesel exhaust particulate (DEP) on immune responses: contributions of particulate versus organic soluble components.

The effect of diesel exhaust particulate (DEP) exposure on innate, cellular and humoral pulmonary immunity was studied using high-dose, acute-exposure rat, mouse, and cell culture models. DEP consists of a complex mixture of petrochemical-derived organics adsorbed onto elemental carbon particles. DEP is a major component of particulate urban air pollution and a health concern in both urban and occupational environments. The alveolar macrophage is considered a key cellular component in pulmonary innate immunity. DEP and DEP organic extracts have been found to suppress alveolar macrophage function as demonstrated by reduced production of cytokines (interleukin-1 [IL-1], tumor necrosis factor- alpha [TNF- alpha]) and reactive oxygen species (ROS) in response to a variety of agents, including lipopolysaccharide (LPS), interferon- gamma (IFN- gamma), and bacteria. Fractionation of DEP organic extract suggests that this activity was predominately in polyaromatic-containing and more polar (resin) fractions. Organic-stripped DEP did not alter these innate pulmonary immune responses. DEP also depressed pulmonary clearance of Listeria monocytogenes and Bacillus Calmette-Guerin (BCG). The contribution of the organic component of DEP is less well defined with respect to acquired and humoral immunity. Indeed, both DEP and carbon black enhanced humoral immune responses (specific immunoglobulin [Ig] E and IgG) in an ovalbumin-sensitized rat model. It is concluded that both the particulate and adsorbed organics may contribute to DEP-mediated immune alterations.

Acute Disease↗

PubMed2004

Asthmalike biphasic airway responses in Brown Norway rats sensitized by dermal exposure to dry trimellitic anhydride powder.

BACKGROUND: Trimellitic anhydride (TMA) can induce specific IgE and occupational asthma. The significance of dermal exposure to TMA in immunologic sensitization and on subsequent airway responses is not clearly known. An animal model displaying both an early-phase airway response (EAR) and a late-phase airway response (LAR) after sensitization and subsequent inhalation challenge to a low-molecular-weight chemical has not been previously reported. OBJECTIVE: The present study investigated EAR and LAR after TMA inhalation challenge in Brown Norway rats sensitized by skin exposure to TMA dry powder. METHODS: Twenty milligrams of dry TMA powder was applied to the skin of each clipped rat's dorsum on days 0, 7, 14, and 21 and occluded overnight with surgical tape. Rats were challenged for 10 minutes with 0.2 to 40 mg/m(3) of TMA aerosol after day 35. Enhanced pause (an index of airway resistance) was recorded overnight in a whole-body plethysmography system. Specific IgE and pulmonary eosinophilia were also measured. RESULTS: Concentration-dependent responses to TMA were observed: provocation with 0.2 mg/m(3) produced no response; 1 mg/m(3) induced only EAR; and 5 mg/m(3) and 40 mg/m(3) induced both EAR and LAR. Specific IgE was positive; airway eosinophilic inflammation was observed. CONCLUSION: TMA powder applied to the skin can lead to both immunologic sensitization and subsequent dose-dependent biphasic airway responses after TMA aerosol challenge.

Administration, Topical↗

PubMed2004

Clinical use of immunoassays in assessing exposure to fungi and potential health effects related to fungal exposure.

OBJECTIVE: To review and summarize current evidence regarding the proper role of immunoassays in clinical assessments of exposure to fungi and health effects related to fungal exposure. DATA SOURCES: We reviewed relevant scientific investigations and previously published reviews concerning this topic. STUDY SELECTION: The authors' clinical, laboratory, and public health experiences were used to evaluate relevant data for scientific merit. RESULTS: Testing to determine the presence of IgE to specific fungi may be a useful component of a complete clinical evaluation in the diagnosis of illnesses that can be caused by immediate hypersensitivity such as allergic rhinitis and asthma. Detection of IgG to specific fungi has been used as a marker of exposure to agents that may cause illnesses such as hypersensitivity pneumonitis. However, the ubiquitous nature of many fungi and the lack of specificity of fungal antigens limit the usefulness of these types of tests in the evaluation of potential building-related illness and fungal exposure. Specific serologic tests (such as tests for cryptococcal antigen, coccidioidal antibody, and Histoplasma antigen) have been shown to be useful in the diagnosis of some fungal infections, but these are the exception not the rule. CONCLUSIONS: There is currently not enough scientific evidence to support the routine clinical use of immunoassays as a primary means of assessing environmental fungal exposure or health effects related to fungal exposure. Health care providers who care for persons expressing concerns about the relationship of symptoms to potential exposure to fungi are advised to use immunoassay results with care and only as an adjunct to a comprehensive approach to patient care.

Animals↗

PubMed2004

New-onset asthma associated with exposure to 3-amino-5-mercapto-1,2,4-triazole.

OBJECTIVE: The authors conducted an investigation of a cluster of eight new-onset asthma cases identified in a chemical plant through the Sentinel Event Notification Systems for Occupational Risks (SENSOR) program. METHODS: Workplace investigation involved interviews with the asthma cases, review of medical records, and medical and industrial hygiene surveys in the plant. RESULTS: Altogether, 11 work-related asthma cases were identified among the plant workers-approximately 10% of the workers exposed to the potential causative agents: 3-amino-5-mercapto-1,2,4-triazole (AMT) or N-(2,6-difluorophenyl)-5-methyl-[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide (DE-498; trade name Flumetsulam). Of these cases, six had physician-diagnosed occupational asthma (OA) based on work-related respiratory symptoms and nonspecific bronchial hyperresponsiveness (NSBH), and of these, three had work-related expiratory peak flow changes. CONCLUSIONS: The findings of this investigation, together with findings from concurrent animal studies, suggest that this outbreak of new-onset asthma was associated with exposure to AMT. CLINICAL SIGNIFICANCE: A cluster of eight new-onset asthma cases was identified in a chemical plant through the SENSOR program. Subsequent workplace investigation identified AMT, used in the production of a herbicide N-(2,6-difluorophenyl)-5-methyl- [1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide, as the most likely causal agent.

Asthma↗

PubMed2003

Characterization of DNA adducts from lung tissue of asphalt fume-exposed mice by nanoflow liquid chromatography quadrupole time-of-flight mass spectrometry.

A bioanalytical method based on nanoflow liquid chromatography coupled to a hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometry was developed to characterize selected polyaromatic hydrocarbon (PAH)-DNA adducts. The collision-induced dissociation of analytes results in characteristic fragmentation patterns that can be utilized to identify the DNA adducts. In the experiment, 32 B6C3F1 mice were exposed daily (4h/day) to asphalt fume in a whole-body inhalation chamber for 10 days; 16 nonexposed mice served as controls. The asphalt fume was generated at 180 degrees C and the concentrations of PAHs in the animal exposure chamber ranged from 152 to 198 mg/m3. The DNA adducts N2-deoxyguanosine-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (N2-dG-BPDE); N6-deoxyadenosine-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (N6-dA-BPDE), and N4-deoxycytidine-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (N4-dC-BPDE) were identified. The concentrations of N2-dG-BPDE, N6-dA-BPDE, and N4-dC-BPDE adducts were determined to be 1.17, 0.97, and 0.68 pmol/mg DNA, respectively, in the lung tissue of exposed mice using the nanoflow technique. The total DNA adducts in exposed lung tissue was determined to be 8.35 pmol/mg DNA by 32P-postlabeling assay. In total, the results indicated that PAH DNA adducts were significantly elevated (p < 0.001) in the lung tissue of asphalt-fume-exposed mice relative to tissue from control animals.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed2003

Urinary benzo[a]pyrene and its metabolites as molecular biomarkers of asphalt fume exposure characterized by microflow LC coupled to hybrid quadrupole time-of-flight mass spectrometry.

As a step to study the health effects of asphalt fume exposure, an analytical method was developed to characterize benzo[a]pyrene and its hydroxy metabolites in the urine of asphalt fume-exposed rats. This method is based on microflow liquid chromatography (LC) coupled to hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometry (Q-TOFMS). Twenty-four female Sprague-Dawley rats were used in the experiment, with 8 as controls and 16 exposed to asphalt fumes in a whole-body inhalation chamber for 10 days (4 h/day). Generated at 150 degrees C, the asphalt fume concentration in the animal exposure chamber ranged 76-117 mg/m(3). In the urine of the asphalt fume-exposed rats, benzo[a]pyrene and its metabolites of 3-hydroxybenzo[a]pyrene, benzo[a]pyrene-7,8-dihydrodiol(+/-), and benzo[a]pyrene-7,8,9,10-tetrahydrotetrol(+/-) were identified, and their concentrations were determined at 2.19 +/- 0.49, 16.17 +/- 0.3, 6.28 +/- 0.36, and 29.35 +/- 0.26 ng/100 mL, respectively. The metabolite concentrations from the controlled group, however, were either under the detection limits or at a relatively very low level (0.19 +/- 0.41 ng/100 mL for benzo[a]pyrene-7,8,9,10-tetrahydrotetrol metabolite). The results clearly indicate that the benzo[a]pyrene and its hydroxy metabolites were significantly elevated (p < 0.001) in the urine of asphalt fume-exposed rats relative to controls. The study also demonstrated that the combination of microflow LC separation and collision-induced dissociation leading to a characteristic fragmentation pattern by hybrid Q-TOFMS offers a distinct advantage for the identifications and characterizations of the benzo[a]pyrene metabolites.

Journal Article↗

PubMed2003

Identification of organic fractions of diesel exhaust particulate (DEP) which inhibit nitric oxide (NO) production from a murine macrophage cell line.

Diesel exhaust particulates (DEPs) can constitute a large component of the particulate air pollution in urban areas and is a health concern. The effects of DEP on nitric oxide (NO) production by a murine macrophage cell line (RAW264.7) in response to interferon-gamma (INFgamma), lipopolysaccharide, (LPS) and Bacillus Calmette-Guerin (BCG) were studied. The DEP was fractionated into organic and inorganic fractions (carbonaceous core). The organic portion was further divided into asphaltene, saturates, less polar aromatics, more polar aromatics and resins-containing fractions. Each fraction was tested for the ability to suppress NO production from BCG-stimulated macrophages. DEP crude organic extract, more polar aromatic hydrocarbon, and resin fractions dose-dependently inhibited BCG-stimulated NO production. It is concluded that the responsiveness of the macrophages to stimuli, such as BCG, is suppressed by DEP and that this activity is most predominant in the polar aromatic hydrocarbons and resins-containing fractions.

Air Pollutants↗

PubMed2003

Effect of diesel exhaust particulate on bacillus Calmette-Guerin lung infection in mice and attendant changes in lung interstitial lymphoid subpopulations and IFNgamma response.

The effect of exposure to diesel exhaust particulate (DEP) on bacillus Calmette-Guerin (BCG) lung infection in mice was studied. C57Bl/6J female mice were infected with BCG (2.5 x 104 bacteria/mouse) by intrapulmonary instillation, with or without coadministration of DEP (100 microg/mouse). Five weeks later, mice exposed to DEP + BCG had about a four-fold higher BCG load in the lungs than mice exposed only to BCG (p < 0.05). DEP treatment alone had no effect on the total number of lung lymphocytes or numbers of T, B, or NK cells recovered from lungs. In contrast, BCG infection significantly increased (p< 0.05) recovery levels of all types of lymphocytes from lungs. Coexposure to DEP + BCG further increased the recovery of lymphocytes from lungs of BCG-infected mice. The pulmonary lymphocyte subpopulation expressing the greatest levels of mRNA for IFNgamma after BCG infection was CD4+ T cells. Expression levels were similar in mice exposed to BCG or BCG + DEP and were elevated as compared to noninfected mice and mice treated with DEP alone. Recovery of IFNgamma-secreting lymphocytes and IFNgamma-secreting T cells was significantly higher (p < 0.05) from lungs of BCG-infected mice as compared to control or DEP-exposed mice. BCG and BCG + DEP groups of mice did not differ significantly in the numbers of IFNgamma-secreting lymphocytes in lungs. Taken together, these results indicated that coexposure to DEP + BCG did not significantly affect the level of IFNgamma response of mice to BCG infection. However, DEP treatment was found to inhibit IFNgamma-induced nitric oxide (NO) production by mouse alveolar macrophages in vitro. Our results indicate that DEP exposure did not alter the IFNgamma response to BCG infection, but reduced responsiveness of alveolar macrophages to IFNgamma. Reduced sensitivity of DEP-exposed alveolar macrophages to IFNgamma may contribute to a greater load of BCG in the lungs of BCG-infected mice given DEP.

Animals↗

PubMed2003

Evidence for lipopolysaccharide-induced differentiation of RAW264.7 murine macrophage cell line into dendritic like cells.

Effect of lipopolysaccharide (LPS) on RAW264.7 macrophage cell line was studied. LPS-treated RAW264.7 cells increased in cell size and acquired distinct dendritic morphology. At the optimal dose of LPS (1 mg/ml), almost 70% RAW264.7 cells acquired dendritic morphology. Flow cytometric studies indicate that the cell surface markers known to be expressed on dendritic cells and involved in antigen presentation and T cell activation (B 7.1, B 7.2, CD40, MHC class II antigens and CD1d) were also markedly upregulated on LPS-treated RAW 264.7 cells. Our results suggest the possibility that LPS by itself could constitute a sufficient signal for differentiation of macrophages into DC-like cells.

Animals↗

PubMed2003

Identification and quantification of urinary benzo[a]pyrene and its metabolites from asphalt fume exposed mice by microflow LC coupled to hybrid quadrupole time-of-flight mass spectrometry.

Prolonged, extensive exposure to asphalt fume has been associated with several adverse health effects. Inhaled polycyclic aromatic hydrocarbons (PAHs) from asphalt fume exposure have been suspected of inducing such effects. In this study, a bioanalytical method was proposed and evaluated to identify and quantify benzo[a]pyrene and its hydroxy-metabolites. This method is based on coupling a microflow liquid chromatography (LC) to a hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometry (Q-TOFMS). In the experiment, thirty-two B6C3FI mice were exposed to asphalt fume in a whole body inhalation chamber for 10 days (4 h day(-1)) and twelve other mice were used as controls. The asphalt fume was generated at 180 degrees C and the concentrations in the animal exposure chamber ranged 175-182 mg m(-3). Benzo[a]pyrene and its metabolites of 3-hydroxybenzo[a]pyrene, benzo[a]pyrene-7,8-dihydrodiol(+/-), benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide(+/-), and benzo[a]pyrene-7,8,9,10-tetrahydrotetrol(+/-) in the urine of asphalt fume exposed mice were identified and found at 3.18 ng 100 mL(-1), 31.36 ng 100 mL(-1), 11.56 ng 100 mL(-1), 54.92 ng 100 mL(-1), and 45.23 ng 100 mL(-1) respectively. The results revealed that the urinary benzo[a]pyrene and its hydroxy-metabolites from exposed mice were at significantly higher levels (p < 0.001) than those from the control groups. Compared with several other technologies such as HPLC-UV and HPLC-fluorescence, the new method is more sensitive and selective, and it can also provide additional useful information on the structures of the metabolites. Hence, this method can be used to perform the assessment and to study the mechanisms of the adverse health effects. The fragmentation patterns established in this study can also be used to identify and quantify PAH metabolites in other biological fluids.

Animals↗

PubMed2002

Murine model of BCG lung infection: dynamics of lymphocyte subpopulations in lung interstitium and tracheal lymph nodes.

C57Bl/6 female mice were infected with an intrapulmonary dose of 2.5 x 10(4) BCG (Mycobacterium bovis Bacillus Calmette-Guerin). Lymphocyte populations in lung interstitium and lung-associated tracheal lymph nodes (LN) were examined at 1, 2, 4, 5, 6, 8 and 12 weeks after infection. BCG load in lungs peaked between 4-6 weeks post-infection and declined to very low levels by the 12th week of infection. Lung leukocytes were obtained over the course of infection by enzyme digestion of lung tissue followed by centrifugation over Percoll discontinuous density gradients. By 4 to 6 weeks after infection, numbers of lung leukocytes had more than doubled but the proportions of lymphocytes (about 70%), macrophages (about 18%) and granulocytes (about 12%) remained essentially unaltered. Flow cytometric studies indicated: (i) the total number of CD3+ T cells in lungs increased by 3-fold relative to uninfected controls at 5 to 6 weeks post-infection, but the relative proportions of CD4 and CD8 cells within the T cell compartment remained unaltered; (ii) relative proportion of NK cells in lungs declined by 30% but the total number of NK cells (NK1.1+) per lung increased by about 50%, 5-6 weeks post infection; (iii) tracheal LN underwent marked increase in size and cell recoveries (6-10-fold increase) beginning 4 weeks after infection. While both T and B cells contributed to the increase in cell recoveries from infected tracheal LNs, the T/B ratio declined significantly but CD4/CD8 ratio remained unaltered. In control mice, IFNgamma producing non-T cells outnumbered T cells producing IFNgamma. However, as the adaptive response to infection evolves, marked increase occur in the number of IFNgamma producing T cells, but not NK cells in the lungs. Thus, T cells are the primary cell type responsible for the adaptive IFNgamma response to pulmonary BCG infection. Few T cells in tracheal LN of BCG infected mice produce IFNgamma, suggesting that maturational changes associated with migration to the lungs or residence in the lungs enhance the capability of some T cells to produce this cytokine.

Animals↗

PubMed2002

Immunotoxicology of organic acid anhydrides (OAAs).

Organic acid anhydrides (OAAs) have considerable economic importance due to their extensive use in the production of alkyd, epoxy, and polyester resins. Occupational exposure to OAAs has been associated with a variety of health effects, which may be classified into two major categories of direct toxicity/irritant and hypersensitivity. The hypersensitivity diseases associated with OAA exposure are thought to be related to the reactivity of these chemicals and in particular their ability to form protein conjugates that may be recognized as neo-antigens by the immune system. This review will present a brief discussion of the basic chemistry of these compounds and the environmental and biological monitoring methods used for exposure measurements. The clinical syndromes associated with exposure to these compounds will be discussed along with factors that may affect disease susceptibility. Finally, animal models that have been developed to examine the mechanisms of disease will be discussed.

Anhydrides↗

PubMed2002

Allergic and latex-specific sensitization: route, frequency, and amount of exposure that are required to initiate IgE production.

Quantitative data that documents human exposure-response relationships for IgE sensitization to allergens are limited. Although seemingly straightforward, documentation of exposure-response relationships can be difficult. Issues that are related to study design, allergen standardization, exposure assessment, and evaluation for sensitization can impact greatly on study results. Despite these issues, exposure-response relationships for sensitization to protein allergens have been documented in several occupational groups, which include enzyme-detergent workers, bakers, and laboratory animal workers. In general, atopy acts as an effect modifier in these settings, steepening the exposure-response relationship. Several studies suggest that the greatest risk for sensitization is within the first several years of exposure. For 1 allergen, the protease subtilisin, a short-term exposure limit of 60 ng/m(3) has been recommended by the American Council of Governmental Industrial Hygienists. With regard to natural rubber latex, exposure-related factors such as number of operations have been shown to be risk factors for sensitization of children with spina bifida. By contrast, fewer studies show exposure-response relationships for IgE sensitization of health care workers to natural rubber latex, and the area remains controversial. However, a recent cohort study that evaluated incident sensitization in dental hygiene students suggests strongly that, with sufficient exposure, employment in health care can lead to an increased risk of IgE sensitization to natural rubber latex.

Air Pollutants, Occupational↗

PubMed2002

Evaluation of self-reported skin problems among workers exposed to toluene diisocyanate (TDI) at a foam manufacturing facility.

Toluene diisocyanate, or TDI (CAS 584-84-9) is a well-known asthmagen and respiratory irritant. TDI is also known for its ability to irritate the skin and mucous membranes. To further investigate the dermal effects of TDI, NIOSH investigators conducted a cross-sectional study at a flexible foam manufacturing plant. A total of 114 workers participated in the study. Participants completed a medical questionnaire, provided blood for antibody testing to TDI and other allergens, and a subset of participants reporting skin symptoms underwent skin patch testing to a standard diisocyanate panel. Production line workers were more than twice as likely to report skin problems as those working in nonproduction areas (PRR = 2.66; 95% CI = 1.14-16.32; P = 0.02). Age, gender and duration of employment at the plant were comparable among participants working in production and nonproduction areas. Of the 100 participants who provided blood samples for antibody testing, specific IgG antibody to TDI was detected in two individuals, and none of the samples demonstrated specific IgE antibody to TDI. Of the 26 workers who underwent skin patch testing, none developed reactions to the diisocyanate allergens. These results suggest that the skin symptoms among study participants represent an irritant rather than an immunologic reaction to TDI, or to an unidentified allergen present in the foam.

Adult↗

PubMed2002

Dose-dependent thiol and immune responses to ovalbumin challenge in Brown Norway rats.

Dose-dependent specific antibody production, antigen-dependent pulmonary inflammation, and thiol changes in the lung and associated lymph nodes were examined in a Brown Norway rat model of pulmonary sensitization. Cysteine (CYSH), glutathione (GSH), and markers of inflammation in bronchoalveolar lavage fluid (BALF) were measured following ovalbumin (OVA) inhalation challenge. Alveolar macrophages (AM) and pulmonary-associated lymph node cells (LNC) were isolated and intracellular CYSH and GSH assessed. OVA-specific IgE and IgG antibodies were quantified from sera. A dose-dependent biphasic response was noted with respect to OVA-specific IgE. OVA-specific IgG concentrations were maximal at 68 mg (OVA)/m3. OVA challenge to sensitized rats induced increases in BALF albumin, total protein, lactate dehydrogenase, CYSH and GSH that were independent of serum antibody concentrations. AM thiols were modestly elevated at low OVA challenge doses, but sharply reduced at the higher OVA challenge doses. In contrast, both thiols were dose dependently elevated in BALE CYSH, but not GSH, was elevated in LNC of OVA challenged rats. In summary, antigen exposure caused a dose-dependent alteration of inflammatory, thiol and immune parameters in OVA sensitized and challenged rats. Changes in thiol levels did not correlate with antibody responses. While the results of the present study do not support a functional role for thiols in the immune response, it is important to note the dose-dependent dramatic alteration seen in thiols following sensitization and challenge.

Animals↗

PubMed2002

Alteration of intracellular cysteine and glutathione levels in alveolar macrophages and lymphocytes by diesel exhaust particle exposure.

The purpose of this study was to characterize the effects of diesel exhaust particles (DEP) on thiol regulation in alveolar macrophages (AM) and lymphocytes. We obtained AM and lymph node (thymic and tracheal) cells (LNC) (at different time points) from rats exposed intratracheally to DEP (5 mg/kg) or saline, and measured inflammatory markers, thiol levels, and glutathione reductase (GSH-R) activity. DEP exposure produced significant increases in neutrophils, lactate dehydrogenase, total protein, and albumin content in the lavage fluid. AM from DEP-exposed rats showed a time-dependent increase in intracellular cysteine (CYSH) and GSH. In LNC the intracellular GSH reached peak level by 24 hr, declining toward control levels by 72 hr after exposure. LNC-CYSH and AM-CYSH and GSH were increased at both 24 and 72 hr. Both Sprague-Dawley and Brown Norway rats showed similar trends of responses to DEP exposure as per measurement of the inflammatory markers and thiol changes. AM and, to a lesser degree, LNC were both active in cystine uptake. The DEP exposure stimulated GSH-R activity and increased the conversion of cystine to CYSH in both cell types. The intracellular level of GSH in DEP-exposed AM was moderately increased compared with the saline control, and was further augmented when cells were incubated with cystine. In contrast, the intracellular level of GSH in DEP-exposed LNC was significantly reduced despite the increased CYSH level and GSH-R activity when these cells were cultured for 16 hr. DEP absorbed 23-31% of CYSH, cystine, and GSH, and only 8% of glutathione disulfide when incubated in cell free media. These results indicate that DEP exposure caused lung inflammation and affected thiol levels in both AM and LNC.

Animals↗