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Biomedical subjects

D H Eidelman

Publications and source records attributed to D H Eidelman.

At least 19 recordsLinked to original sources
PubMed2003

Analysis of glutathione in rat airway surface liquid by capillary zone electrophoresis with conductivity detection.

Glutathione (GSH) is an important component of antioxidant defenses in airway surface liquid (ASL), a thin layer (10-30 microm) of liquid covering the epithelial cells lining the airways of the lung. Decreased levels of ASL GSH have been reported in cystic fibrosis (CF), potentially contributing to the severe oxidative stress seen in this disease. To help investigate the role of GSH in ASL, we developed a technique suitable for analysis of GSH and its oxidized form (GSSG) in microliter samples using capillary sampling followed by capillary zone electrophoresis (CZE) analysis with conductivity detection. CZE was carried out in 100 mM CHES and 40 mM lithium hydroxide with 5 mM spermine at pH 9.1 under an applied electric field of -416 V cm(-1). To prevent any autooxidation of GSH during sample manipulations, the samples were treated with N-ethylmaleimide (50 mM) to alkylate free thiol (-SH). Under these conditions, GSH and GSSG were cleanly separated without interference from common anions (e.g. Cl(-), PO(4)(3-), HCO(3)(-), etc.) and the limit of detection for ASL analysis was 11 microM for GSH and 8 microM for GSSG (S/N=3). GSH and GSSG were also measured in rat plasma. Baseline values of 897+/-210 microM (GSH) and 215+/-61 microM (GSSG) were obtained for rat ASL (n=8), whereas 12.4+/-2.7 microM (GSH) and 14.8+/-6.7 microM (GSSG) were obtained for rat plasma (n=5).

Animals↗
PubMed2001

Greater velocity and magnitude of airway narrowing in immature than in mature rabbit lung explants.

Methacholine (MCh)-induced bronchoconstriction in vivo produces greater maximal increases in pulmonary and airway resistances in immature than in mature rabbits. Our recent findings of lower shear modulus and greater airway distensibility suggest a lower elastic load limiting airway smooth muscle (ASM) shortening in immature rabbit lungs. We hypothesized that a lower elastic load should result in greater velocity of airway narrowing. Lung explants were prepared from three immature and five mature rabbits. Dynamic narrowing of intraparenchymal airways after maximal MCh stimulation was assessed by video microscopy. Immature airways (n = 80) compared with mature airways (n = 110) demonstrated greater peak velocity of shortening (6.98 +/- 0.32 versus 4.22 +/- 0.18% of baseline perimeter/s) and greater maximal airway narrowing, expressed as percentage of baseline area (31.9 +/- 1.6 versus 42.2 +/- 1.8%). For both groups, a greater velocity of shortening resulted in greater airway narrowing. As available data do not support maturational differences in rabbit ASM, our results are consistent with a lower elastic load limiting ASM shortening in the immature rabbit.

Age Factors↗
PubMed2001

Capillary electrophoresis analysis of nitrite and nitrate in sub-microliter quantities of airway surface liquid.

We developed a simple capillary electrophoresis (CE) method to measure nitrite and nitrate concentrations in submicroliter samples of rat airway surface liquid (ASL), a thin (10-30 microm) layer of liquid covering the epithelial cells lining the airways of the lung. The composition of ASL has been poorly defined, in large part because of the small sample volume (approximately 1-3 microl per cm2 of epithelium) and difficulty of harvesting ASL. We have used capillary tubes for ASL sample collection, with microanalysis by CE using a 50 mM phosphate buffer (pH 3), with 0.5 mM spermine as a dynamic flow modifier, and direct UV detection at 214 nm. The limit of detections (LODs), under conditions used, for ASL analysis were 10 microM for nitrate and 30 microM for nitrite (SIN= 3). Nitrate and nitrite were also measured in rat plasma. The concentration of nitrate was 102+/-12 microM in rat ASL and 70+/-1.0 microM in rat plasma, whereas nitrite was 83+/-28 microM in rat ASL and below the LOD in rat plasma. After instilling lipopolysaccharide intratracheally to induce increased NO production, the nitrate concentration in ASL increased to 387+/-16 microM, and to 377+/-88 microM in plasma. The concentration of nitrite increased to 103+/-7.0 microM for ASL and 138+/-17 microM for plasma.

Animals↗
PubMed2001

Eosinophil peroxidase mediates protein nitration in allergic airway inflammation in mice.

The eosinophilic inflammatory response in asthma is associated with protein nitration, detected as immunostaining for 3-nitrotyrosine (3NT). As the presence of 3NT is strongly correlated with upregulation of the inducible form of nitric oxide synthase (NOS II), it has been hypothesized that 3NT formation results from the action of peroxynitrite (ONOO-), a highly reactive NO derivative produced from the reaction of molecular NO and O2-. However, recent observations have suggested that the action of peroxidases, including eosinophil peroxidase (EPO), may be responsible for protein nitration. In this study, we used murine models of allergic asthma to address the relative contribution of EPO and NOS II to protein nitration. We studied EPO-deficient New Zealand White (NZW) mice, which were sensitized and challenged intranasally with ovalbumin (OVA). Despite comparable levels of eosinophilia, NO, and superoxide production, NZW mice exhibited markedly decreased 3NT staining around the airways after OVA challenge when compared with two other strains (A/J and C57BL/6J). Immunocytochemical analysis of bronchoalveolar lavage (BAL) cells and lung sections suggested that 3NT staining was largely confined to eosinophils. This was confirmed by Western Blot analysis of proteins from different subsets of BAL cells that demonstrated a marked decrease in 3NT formation in eosinophils from NZW mice. These results contrast with those obtained in OVA-sensitized and -challenged NOS II deficient mice, which despite decreased NO production, exhibited similar 3NT staining in the airways after OVA challenge as in wild-type control mice. In this model, protein nitration was thus not a function of NO production by NOS II. We conclude that in the mouse, 3NT formation after specific allergen challenge is dependent on EPO activity, particularly in eosinophils themselves. In contrast, 3NT formation is not driven by upregulation of NOS II expression in this model and does not appear to depend on increases in the level of NO production.

Animals↗
PubMed2001

Respiratory mechanics and lung development in the rat from early age to adulthood.

The purpose of the present study was to establish how the dependence of respiratory mechanics on lung inflation changes during development. We studied seven groups of rats from 10 days to 3 mo of age at five levels of positive end-expiratory pressure (PEEP) from 0 to 7 hPa (1 hPa = 0.1 kPa approximately 1 cmH(2)O). At each PEEP level, we measured respiratory system resistance and elastance at both 0.9 and 4.8 Hz to partition the mechanical properties into its airway and tissue components. Elastance increased more rapidly with PEEP in the younger animals, which we interpret as reflecting a more pronounced strain stiffening of the younger parenchyma. However, the decrease in airway resistance with PEEP was more pronounced in the older animals. Morphometric analysis showed that mean tissue density decreased and total alveolar surface area increased with age. Our data suggest that the mechanical interdependence between airways and parenchyma is weaker in very young animals compared with mature animals. This may play a role in the hyperresponsiveness of immaturity.

Aging↗
PubMed2001

Nitric oxide and protein nitration are eosinophil dependent in allergen-challenged mice.

To explore the possible role of eosinophils in NO-mediated tissue injury, we studied a murine model of allergic asthma. Male A/J mice were sensitized and challenged intranasally with ovalbumin (OVA). Following challenge, the number of eosinophils in bronchoalveolar lavage fluid (BALF) increased from 0.4% of total cells at baseline (0.02 x 10(4) cells/ml) to 60.2% at 48 h after the challenge (9.34 x 10(4) cells/ml). The rise in eosinophil count was accompanied by a 40.3% increase in total NO(2-) plus NO(3-) (NO(x)) in BALF. This in turn was accompanied by expression of inducible NO synthase (NOS II) in airway epithelial and inflammatory cells, as well as by evidence of staining for 3-nitrotyrosine (3NT) in peribronchial inflammatory cells and at the epithelial surface. Both NO(x) production and 3NT were significantly reduced by pretreatment of the challenged mice with the highly specific NOS II inhibitor N-3-aminomethyl-benzyl-acetamidine-dihydrochloride (1400W), as well as by the nonselective NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME). L-NAME and 1400W also reduced the number of BALF eosinophils (37.2% and 61.5%, respectively, as compared with the control value), suggesting that NO production by NOS II contributes to eosinophil recruitment. To further examine the role of eosinophils, we pretreated additional mice with an anti-interleukin (IL)-5 antibody, which reduced BALF eosinophilia following OVA challenge by 90.1%. In concert with the decrease in eosinophils, the anti-IL-5 antibody reduced NO(x) in BALF almost to the baseline value, and decreased the number of 3NT-positive cells in the peribronchial region by 74.4%. Western blot analysis of protein extracted from whole lung confirmed the reduction in tyrosine nitration by anti-IL-5 antibody. These findings indicate that NO and eosinophilic inflammation are closely coupled, and suggest that eosinophils are an important source of tyrosine nitration.

Analysis of Variance↗
PubMed2000

The contribution of airway smooth muscle to airway narrowing and airway hyperresponsiveness in disease.

Airway hyperresponsiveness (AHR), the exaggerated response to constrictor agonists in asthmatic subjects, is incompletely understood. Changes in either the quantity or properties of airway smooth muscle (ASM) are possible explanations for AHR. Morphometric analyses demonstrate structural changes in asthmatic airways, including subepithelial fibrosis, gland hyperplasia/hypertrophy, neovascularization and an increase in ASM mass. Mathematical modelling of airway narrowing suggests that, of all the changes in structure, the increase in ASM mass is the most probable cause of AHR. An increase in ASM mass in the large airways is more closely associated with a greater likelihood of dying from asthma than increases in ASM mass in other locations within the airway tree. ASM contraction is opposed by the elastic recoil of the lungs and airways, which appears to limit the degree of bronchoconstriction in vivo. The cyclical nature of tidal breathing applies stresses to the airway wall that enhance the bronchodilating influence of the lung tissues on the contracting ASM, in all probability by disrupting cross-bridges. However, the increase in ASM mass in asthma may overcome the limitation resulting from the impedances to ASM shortening imposed by the lung parenchyma and airway wall tissues. Additionally, ASM with the capacity to shorten rapidly may achieve shorter lengths and cause a greater degree of bronchoconstriction when stimulated to contract than slower ASM. Changes in ASM properties are induced by the process of sensitization and allergen-exposure such as enhancement of phospholipase C activity and inositol phosphate turnover, and increases in myosin light chain kinase activity. Whether changes in ASM mass or biochemical/biomechanical properties form the basis for asthma remains to be determined.

Animals↗
PubMed2000

Upregulation of the transcription factor GATA-3 in upper airway mucosa after in vivo and in vitro allergen challenge.

BACKGROUND: Allergic rhinitis is a complex upper airways disorder characterized by the infiltration of eosinophils and T(H2)-type T lymphocytes. GATA-3 is a novel transcription factor recently shown to regulate IL-5 and, possibly, IL-4 gene expression. We previously reported that GATA-3 is increased within the bronchial mucosa of allergic asthmatic subjects compared with control subjects. OBJECTIVE: In the present study we set out to determine whether there is also an increased number of cells expressing GATA-3 messenger (m)RNA within the nasal mucosa of patients with allergic rhinitis. METHODS: Inferior turbinate biopsy specimens were obtained from patients with allergic rhinitis and nonatopic control subjects before and after local allergen provocation in vivo. To assess the contribution of resident cells expressing GATA-3 mRNA, we also performed isolated explant studies in which nasal mucosal tissue from subjects with allergic rhinitis and nonatopic control subjects was cultured in allergen-treated medium. The presence of mRNA coding for GATA-3, IL-5, IL-4, IL-13, and GM-CSF was assessed by using in situ hybridization. RESULTS: The number of GATA-3 mRNA(+) cells was increased after local allergen provocation in vivo (increase in GATA-3 mRNA(+) cells [mean +/- SEM]: subjects with allergic rhinitis, 11.3 +/- 8.7; control subjects, 1.2 +/- 4.1; P <.05) and in explanted nasal mucosa in vitro (subjects with allergic rhinitis, 10. 2 +/- 3.8; control subjects, 2.7 +/- 4.4; P <.05). The gene expression of GATA-3 was significantly correlated to the numbers of IL-5 (r = 0.87) and GM-CSF (r = 0.79) mRNA(+) cells but not with IL-4 or IL-13 mRNA(+) cells. CONCLUSION: In summary, the expression of the transcription factor GATA-3 was increased after allergen challenge, and this was evident in the absence of de novo inflammatory cell recruitment. GATA-3 may be a potential target in the treatment of allergic diseases, such as rhinitis.

Allergens↗
PubMed2000

Airway surface liquid composition in mice.

Airway surface liquid (ASL) lines the conducting airways of the respiratory tract. We collected small samples of this liquid from the lower tracheae of anesthetized C57BL/6 mice and determined its ionic composition (in mM: 87.2 Na(+), 4.7 K(+), and 57.0 Cl(-)). Intravenous methacholine produced significant increases in the concentrations of Na(+), K(+), and Cl(-) within ASL. A limited analysis of liquid from cystic fibrosis transmembrane conductance regulator (CFTR) knockout mice revealed no significant differences compared with littermate controls; however, Pseudomonas aeruginosa infection led to an increase in the salt concentration of ASL in cftr(+/+) mice. Morphometric measurements of tracheal submucosal gland volume revealed significant differences between inbred mouse strains, corresponding to ease of ASL collection. We conclude that although submucosal glands may be responsible for the production of some ASL, the ionic composition of this liquid is actively regulated by the underlying epithelial cells.

Animals↗
PubMed2000

Bronchial responsiveness among inbred mouse strains. Role of airway smooth-muscle shortening velocity.

To investigate the relationship between bronchial responsiveness and airway smooth-muscle (ASM) contractile properties, we studied inbred mice with known interstrain differences in airway responsiveness. Using oscillatory mechanics, we confirmed that A/J mice were hyperresponsive to methacholine (MCh) as compared with mice of the C3H/HeJ and C57BL/6J strains. Analysis of respiratory system resistance and elastance at different flow oscillation frequencies indicated that interstrain differences in responsiveness are present in both central and peripheral airways of these mice. We used video microscopy to measure the rate of contraction of explanted airways, and found that the airways of A/J mice contracted more rapidly than those of C3H/HeJ or C57BL/6J mice. In studies of a fourth strain (Balb/C) of mice, we found both bronchial hyperresponsiveness and increased ASM shortening velocity. The rank order of responsiveness among strains was the same as that for shortening velocity (A/J > Balb/C > C3H/HeJ > C57BL/6J). Furthermore, in each strain of mice, shortening velocity correlated with the achieved degree of airway narrowing and with a greater likelihood of airway closure in individual airways. In contrast, generation of isometric tension in trachealis, morphometric measurements of tracheal ASM, tracheal myosin content, and dose-response curves for MCh of explanted intraparenchymal bronchi failed to correspond to the in vivo phenotype of airway reactivity. These results indicate that bronchial responsiveness is related to ASM shortening velocity, and underscore the importance of smooth-muscle dynamics in understanding the mechanisms of bronchial responsiveness.

Airway Resistance↗
PubMed1999

Enhanced Ca(2+) mobilization in airway smooth muscle contributes to airway hyperresponsiveness in an inbred strain of rat.

The mechanisms underlying airway hyperresponsiveness are still unknown but increased contractility of airway smooth muscle may play a role. This study sought to demonstrate a relationship between in vivo airway responsiveness and a number of measures of airway smooth muscle responsiveness ex vivo, including intracellular Ca(2+) signaling, by comparing three inbred strains of rat with different degrees of airways responsiveness to methacholine. Lewis, ACI, and Fisher strains of rat were characterized for their pulmonary responses to 5-hydroxytryptamine (5HT) in vivo and Fisher rats were found to be hyperresponsive to 5HT compared with ACI and Lewis rats. The responsiveness of the airways from these strains of rat ex vivo revealed that intraparenchymal airways from Fisher rats significantly narrowed to a greater degree and at a faster rate to 5HT than Lewis rat airways, consistent with their differences in vivo. Intraparenchymal ACI airways, however, narrowed to the same degree as Fisher airways but took longer to do so at a high concentration of 5HT. 5HT caused concentration-dependent increases in intracellular Ca(2+) in airway smooth muscle cells from all three strains of rat, but Fisher and ACI displayed higher responses than Lewis airway smooth muscle. Our results demonstrate that the degree of intracellular Ca(2+) mobilization by 5HT in airway smooth muscle parallels the rate and degree of intraparenchymal airway narrowing and suggest that the degree of intracellular Ca(2+) mobilization plays a role in determining airway smooth muscle contractility.

Airway Resistance↗
PubMed1998

Analysis of proteins in microsamples of rat airway surface fluid by capillary electrophoresis.

A thin layer of airway surface fluid (ASF) lining the pulmonary airways plays an important role in the primary defense mechanisms of the lung against bacterial infection. However, little is known about the composition of ASF due to the thinness (typically 5-30 microm in healthy animals) of the fluid layer and its relative inaccessibility, which causes considerable difficulties in sample collection and subsequent analysis. We have used a novel technique of capillary sampling coupled with capillary electrophoresis (CE) to analyze the protein composition of rat ASF. CE analyses were performed under two different conditions: a borate buffer, pH 9.1, or a phosphate buffer, pH 2.5, with 0.5 mM spermine. The different selectivities afforded by the two methods aid in peak identification, and quantitation of most of the major species was possible using both separation conditions. Albumin, transferrin and globulins are observed to be the major protein components in rat ASF, at concentrations of 28 mg ml(-1), 4.0 mg ml(-1) and 34 mg ml(-1) respectively, in comparison to 31 mg ml(-1), 3.1 mg ml(-1) and 40 mg ml(-1), respectively, in rat plasma.

Albumins↗
PubMed1998

Differential responses of pulmonary arteries and veins to histamine and 5-HT in lung explants of guinea-pigs.

1. The mechanisms by which histamine and 5-HT differentially contract pulmonary arteries and veins are unclear. In lung explants from 26 guinea-pigs, we compared responses of pulmonary arteries and vein to histamine, 5-HT and KCI, and examined potential determinants for the differential responses. Lungs were filled with agarose, sectioned into approximately 1 mm thick slices, and vascular luminal areas measured by image analysis. 2. Histamine and 5-HT produced a concentration-dependent constriction in arteries and veins, greater in the latter. KCl constricted arteries and veins equally. 3. The histamine H1 antagonist chlorpheniramine (10(-4) M) abolished contractions to histamine; the H2 antagonist cimetidine enhanced maximal responses and sensitivity of arteries and veins to histamine, and diminished the differences between their maximal responses; the NO synthase inhibitor Nomega-nitro-L-arginine (L-NOARG) increased the maximal responses of arteries and veins, and the differences between their responses; indomethacin had no effect. 4. Contractions to 5-HT were abolished in arteries and markedly reduced in veins by the 5-HT2 antagonist ketanserin (10(-4) M); L-NOARG potentiated the maximal responses of arteries but not of veins; indomethacin increased the maximal responses of arteries but reduced them in veins. 5. By morphometry, arteries had a greater medial thickness and luminal diameter than veins. 6. The data suggest that in guinea-pigs, H2 receptors are responsible for the differential contractile responses of pulmonary arteries and veins to histamine, whereas endothelium-derived vasoactive substances are responsible for their differential contractile responses to 5-HT.

Animals↗
PubMed1998

Airway-parenchymal interdependence after airway contraction in rat lung explants.

The constriction of pulmonary airways is limited by the tethering effect exerted by parenchymal attachments. To characterize this tethering effect at the scale of intraparenchymal airways, we studied the pattern of parenchymal distortion due to bronchoconstriction in a rat lung explant system. First, we measured the elastic modulus under tension for 2% (wt/vol) agarose alone (37.6 +/- 1.5 kPa) and for agarose-filled lung (5.7 +/- 1.3 kPa). The latter is similar to the elastic modulus of air-filled lung at total lung capacity (4.5-6 kPa) (S. J. Lai-Fook, T. A. Wilson, R. E. Hyatt, and J. R. Rodarte. J. Appl. Physiol. 40: 508-513, 1976), suggesting that explants can be used as a model of lung tissue distortion. Subsequently, confocal microscopic images of fluorescently labeled 0.5-mm-thick explants prepared from agarose-filled rat lungs inflated to total lung capacity (48 ml/kg) were acquired. Images were taken before and after airway constriction was induced by direct application of 10 mM methacholine, and the pattern of parenchymal distortion was measured from the displacement of tissue landmarks identified in each image for 14 explants. The magnitude of the radial component of tissue displacement was calculated as a function of distance from the airway wall and characterized by a parameter, b, describing the rate at which tissue movement decreased with radial distance. The parameter b was 0.994 +/- 0.19 (SE), which is close to the prediction of b = 1 of micromechanical modeling (T. A. Wilson. J. Appl. Physiol. 33: 472-478, 1972). There was significant variability in b, however, which was correlated with the fractional reduction in airway diameter (r = 0.496). Additionally, parenchymal distortion showed significant torsion with respect to the radial direction. This torsion was similar in concentric zones around the airway, suggesting that it originates from inhomogeneity in the parenchyma rather than inhomogeneous airway constriction. Our results demonstrate the significance of the nonlinear mechanical properties of alveolar walls and the anisotropy of the parenchyma in determining the nature of airway-parenchymal interdependence.

Animals↗
PubMed1998

Impaired ability of Cftr knockout mice to control lung infection with Pseudomonas aeruginosa.

The present study was aimed at investigating the innate susceptibility of C57BL/6-Cftrunc/Cftrunc knockout [B6-Cftr (-/-)] mice to pulmonary infection with Pseudomonas aeruginosa. Our results indicate that 58.4% of B6-Cftr (-/-) mice died within 6 d following lung infection with 10(5) P. aeruginosa entrapped in agar beads, whereas only 12.1% of B6-Cftr (+/+) mice died over the same period of time. Moreover, the number of bacteria recovered from the lungs of B6-Cftr (-/-) mice 3 and 6 d after infection was significantly higher than that observed in their littermate controls. No correlation was found between the weight or age of the animals and the number of viable bacteria recovered from the lungs of mice. Histopathological examination of lung sections from P. aeruginosa-infected mice revealed that the infection results in a severe bronchopneumonia. Both B6-Cftr (-/-) knockout mice and their littermate controls developed similar lung pathology during the course of infection. Overall, results reported in the present study suggest that a defect at the Cftr locus leads to an exacerbation of P. aeruginosa lung infection resulting in a dramatically increased mortality rate and higher bacterial load.

Animals↗
PubMed1998

Interleukin-5 expression in the bone marrow of sensitized Balb/c mice after allergen challenge.

Interleukin-5 (IL-5) is a potent eosinophilopoietic factor implicated in the chronic inflammatory cell accumulation accompanying bronchial asthma. However, its role in stimulating eosinophil differentiation within the bone marrow following allergen exposure remains to be elucidated. The aims of our study were to determine the expression of IL-5 within the bone marrow of sensitized and control mice after allergen exposure, and to investigate the cellular phenotype of IL-5-producing cells. Sensitized Balb/c mice were challenged with either ovalbumin (OVA) or sterile saline. After 6 h, the mice were exsanguinated and the bone marrow prepared for cytospins. Bone marrow-derived cells from OVA-sensitized mice exhibited an increase in IL-5 immunoreactivity and mRNA compared with those from nonsensitized control mice (p < 0. 05). After allergen challenge, there was a further increase in IL-5 expression (p < 0.05) within the bone marrow. Both sensitization and allergen challenge resulted in an increase in the number of cells expressing major basic protein (MBP) (p < 0.05). In nonsensitized mice, the IL-5 mRNA was expressed predominantly by CD34-positive (CD34+) progenitor cells. Following sensitization and allergen challenge, CD3-positive (CD3+) T lymphocytes were the major source of this cytokine. These results demonstrate the presence of IL-5 within the bone marrow of normal Balb/c mice. After sensitization and allergen challenge, the increase in IL-5-producing cells within the bone marrow is attributed by T lymphocytes.

Allergens↗
PubMed1998

Local cytokine messenger ribonucleic acid expression and in vitro allergic late phase responses in Brown-Norway rats.

The events subsequent to antigen challenge in allergic asthmatics involve the synthesis of pro-inflammatory cytokines. However, little is known how cytokine gene activation prior to allergen challenge may influence this series of events, nor how cytokine gene expression is related to antigen-induced alterations in lung function. Using a novel in vitro explant technique, we hypothesized that the local expression of cytokines influenced the development of antigen-induced late-onset airway responses, and that alterations in cytokine messenger ribonucleic acid (mRNA) expression were associated with antigen-induced changes in airway luminal area. Explants were prepared from excised lungs of ovalbumin-sensitized Brown-Norway rats. Airways were challenged by direct application of ovalbumin or an irrelevant control antigen. Cryostat sections of explants were used for in situ hybridization and mRNA for interleukin (IL)-2, IL-4 and interferon (IFN)-gamma were detected using radiolabelled probes. We found that the presence of high numbers of cells expressing IFN-gamma and IL-2 mRNA within the airways attenuated the development of antigen-induced late airway responses in sensitized rat lung explants. Furthermore, we observed that cytokine mRNA for IL-4 was significantly increased following allergen exposure in sensitized lung explants exhibiting late airway responses. This study implicates the local expression of interferon-gamma and interleukin-2 messenger ribonucleic acid in the failure of sensitized rat lung explants to exhibit late airway responses, and provides evidence linking local interleukin-4 messenger ribonucleic acid expression to the sequelae of events occurring as a result of antigen exposure within the airways.

Animals↗