Neutrophil recruitment in the respiratory tract of a patient with plasma cell granuloma of the lung.

A 69-year-old woman had plasma cell granuloma of the left middle lobe of the lung. Her symptoms and roentgenologic findings improved with antibiotic treatment. Before treatment, the number of neutrophils and NCA were markedly increased in BAL fluid obtained from the affected region of the left lung and moderately increased in BAL fluid obtained from the nonaffected region of the right lung. The number of neutrophils, the NCA as well as the contents of C5 and C5a des Arg (neutrophil chemotactic factors) in the BAL fluids from both these regions decreased during treatment. These findings suggest that plasma cell granuloma was due to chronic immune and inflammatory reactions in the lung, that neutrophils are involved in development of the symptoms and signs of this disease, and that neutrophil chemotactic factors, including complement-derived factors, are important in neutrophil recruitment at the lesion and in nonaffected parts of the lung.

Anaphylactic challenge causes eosinophil accumulation in bronchoalveolar lavage fluid of guinea pigs. Modulation by betamethasone, phenidone, indomethacin, WEB 2086, and a novel antiallergy agent, SCH 37224.

Eosinophil infiltration into bronchoalveolar areas of the lung has been assessed in guinea pigs sensitized to ovalbumin (OA) and then challenged with the aerosolized antigen. Cell content, histamine, and guinea pig albumin (GPA) have been measured in bronchoalveolar lavage (BAL) fluid from these animals. Extensive eosinophil accumulation resulted from sensitization followed by OA challenge; monocytes that initially accounted for greater than 80% of the BAL cells remained essentially constant, and neutrophils comprised less than 3% of the population throughout. Eosinophils were elevated at 3 h, peaked with a fivefold increase at 24 h, and remained elevated for at least 7 days. Histopathologic changes observed in lungs taken from sensitized guinea pigs 24 h after OA challenge confirm this eosinophilia. Increased histamine and GPA were detected only at 5 min. Oral treatment with betamethasone (ED50 = 0.4 mg/kg), phenidone (ED50 = 15 mg/kg), Sch 37224 (ED50 = 0.5 mg/kg), and WEB 2086 (ED50 = 4 mg/kg) decreased eosinophil accumulation in the BAL fluid, indicating roles for 5-lipoxygenase products and PAF in this multimediator-dependent model of allergic inflammation. On the other hand, 4 mg/kg of indomethacin increased total cells with no effect on eosinophils, precluding a major role for cyclooxygenase products. Sch 37224, an antileukotriene agent and an orally active novel antiallergy agent in sheep, guinea pigs, and humans, is as potent as betamethasone at blocking eosinophil infiltration, suggesting that it may also suppress human pulmonary inflammation.

Pulmonary disease progress in sarcoid patients with and without bronchoalveolar lavage collagenase.

To assess the usefulness of bronchoalveolar lavage (BAL) collagenase measurement in gauging disease severity and outcome in sarcoidosis, we analyzed BAL fluids from 84 patients with sarcoidosis for collagenase and monitored disease progress in these patients for a minimum of 12 months. Twenty patients (24%) were found to have BAL collagenase activity on initial evaluation (collagenase-positive group). Compared with patients without BAL collagenase (collagenase-negative group), the collagenase-positive group had (1) a higher proportion of BAL suppressor T cells (p less than 0.03); (2) a lower helper-suppressor T-cell ratio (p less than 0.002); (3) lower mean percent predicted FEV1, FVC, and DLCO levels (p less than 0.05); and (4) a higher proportion of patients with advanced (Stage 4) disease on chest roentgenogram (p less than 0.001). Significant differences were also observed between the collagenase-positive and collagenase-negative groups during follow-up. A higher proportion (55%, n = 11) of collagenase-positive patients required corticosteroid therapy than did collagenase-negative patients (26%; n = 17; p less than 0.025). Of those who remained untreated, pulmonary function tended to decrease in the collagenase-positive group, whereas mean pulmonary function levels actually improved in the collagenase negative group (p less than 0.05). Of those who required therapy, mean percent predicted FVC and DLCO levels improved significantly after treatment in the collagenase-negative group (p less than 0.01 and p less than 0.05, respectively), whereas an improvement in percent predicted FVC levels only (p less than 0.01) was observed in the collagenase-positive group.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyaluronan reflects the pre-fibrotic inflammation in irradiated rat lung: concomitant analysis of parenchymal tissues and bronchoalveolar lavage.

The pathogenesis of pulmonary fibrosis is a complicated chain of interactions between cells and molecules. During recent years bronchoalveolar lavage (BAL) in patients with various interstitial lung disorders has increased our knowledge of the fibrosis process and focused on new interesting interactions. Here we present an animal model which makes it possible to apply both morphological and immunohistochemical tissue staining to perform bronchoalveolar lavage in the same animal. Irradiation is an established method for experimentally evoking lung fibrosis in animals. Rats received irradiation (30 Gy) to the lower parts of both lungs. Bronchoalveolar lavage was performed in the right lung. The biochemical determination of lavage concentration of hyaluronan (HA) and cellular differential counts were compared with interstitial morphology. Animals were sacrificed and analysed 2, 4, 6, 8 and 10 weeks after irradiation. After 6 weeks a massive increase in connective tissue mast cells was seen in the peribronchial and alveolar-interstitial tissue. This mastocytosis was closely related to a marked increase in HA. It became obvious that, in this model, cellular analysis of BAL fluid did not correctly reflect the cellular changes in the lung interstitium. While BAL revealed a pronounced increase of neutrophils with no--or only very few--mast cells, a concomitant increase in mononuclear cells and mast cells was seen in the lung interstitium. In contrast an increase in HA in BAL correlated well with an increase in HA-deposition in the lung interstitium, indicating that measurement of a non-cellular component, such as HA, may better reflect the tissue inflammation.

Mast cells and pulmonary fibrosis. Identification of a histamine releasing factor in bronchoalveolar lavage fluid.

As elevated bronchoalveolar lavage (BAL) fluid histamine levels are noted in patients with pulmonary fibrosis (PF), we assayed BAL fluid from 16 patients with PF for the presence of a histamine releasing factor (HRF). HRF activity was assayed by measuring release of the preformed mast cell-derived mediators, histamine, or beta-hexosaminidase (beta-hex) from a purified population of IL-3 dependent mouse bone marrow derived mast cells (MBMMC) or human blood basophils. Mean BAL cell free histamine levels in the patients with PF was 1226 +/- 1349 pg/ml, whereas BAL histamine levels in a comparison group of six non-PF patients was 118 +/- 60 pg/ml. HRF was significantly elevated in BAL fluid of patients with PF (mean beta-hex release 24.5 +/- 12.9%; range 6.8 to 52.4%) compared to the non-PF group of patients (mean beta-hex release 7.9 +/- 7.7%; range 1.8 to 20.7%). The PF HRF not only degranulated MBMMC, but also induced the generation of the arachidonic acid metabolite leukotriene C4 from MBMMC (24.6 +/- 4.2 ng leukotriene C4/10(6) MBMMC). The PF HRF did not appear to be a cytokine previously identified in BAL fluid of patients with PF (i.e., platelet derived growth factor or insulin growth factor-1) or a human cytokine able to degranulate human basophils (i.e., IL-1, or granulocyte-macrophage-CSF) as these recombinant human cytokines did not induce MBMMC beta-hex release. Physicochemical characterization of the HRF revealed that it was relatively heat stable, pronase sensitive and on Sephadex G-75 and G-200 column chromatography had an apparent molecular mass of 30 to 50 kDa. The ability of PF BAL to induce beta-hex release from MBMMC was not dependent on IgE as unsensitized or lactic acid treated MBMMC release similar amounts of beta-hex compared to MBMMC sensitized with IgE. Thus, BAL fluid of patients with PF contains an HRF that induces beta-hex release from MBMMC via an IgE-independent mechanism. The presence of the HRF could explain elevated BAL histamine levels in patients with PF.

Antioxidant macromolecules in the epithelial lining fluid of the normal human lower respiratory tract.

We hypothesized that the alveolar structures may contain extracellular macromolecules with antioxidant properties to defend against oxidants. To evaluate this 51Cr-labeled human lung fibroblasts (HFL-1) and cat lung epithelial cells (AKD) were exposed to a H2O2-generating system and alveolar epithelial lining fluid (ELF) from healthy nonsmokers was tested for its ability to protect the lung cells from H2O2-mediated injury. The ELF provided marked antioxidant protection, with most from a H2O-soluble fraction in the 100-300-kD range. Plasma proteins with anti-H2O2 properties were in insufficient concentrations to provide the antioxidant protection observed. However, catalase, a normal intracellular antioxidant, was present in sufficient concentration to account for most of the observed anti-H2O2 properties of ELF. Depletion of ELF with an anticatalase antibody abolished the anti-H2O2 macromolecular defenses of ELF. Since catalase is not normally released by cells, a likely explanation for its presence in high concentrations in normal ELF is that it is released by lung inflammatory and parenchymal cells onto the epithelial surface of the lower respiratory tract during their normal turnover and collects there due to the slow turnover of ELF. It is likely that catalase in the ELF of normal individuals plays a role in protecting lung parenchymal cells against oxidants present in the extracellular milieu.

Effect of bronchoalveolar lavage fluid from patients with sarcoidosis or AIDS on interleukin 1 beta release from alveolar macrophages.

We studied the effect of concentrated surfactant-depleted BALF from 8 normal subjects, 13 patients with sarcoidosis, and 13 patients with AIDS on IL1 beta release by human AM. Adherent target AM were exposed to concentrated BALF in the presence or absence of LPS (1 microgram/ml) for two hours. Control AM were unexposed to BALF. After an additional 24-hour incubation, AM supernatants were collected and measured for IL1 beta by ELISA. No spontaneous IL1 beta release occurred from unstimulated AM. One of the sarcoid-BALF and three of the AIDS-BALF samples induced a small amount of IL1 beta release from unstimulated AM. In LPS-stimulated AM, exposure to normal BALF did not significantly alter IL1 beta release compared to unexposed AM. Exposure to sarcoid-BALF significantly increased the release of IL1 beta, while exposure to AIDS-BALF significantly reduced the IL1 beta level in the AM supernatants. The latter effect was related to the higher mortality induced by AIDS-BALF in AM. These data show that release of IL1 beta from LPS-stimulated AM is modified by a short exposure to a sample of alveolar fluid from patients with lung disease.

Pulmonary reaction to long and short asbestos fibers is independent of fibroblast growth factor production by alveolar macrophages.

The role of alveolar macrophage (AM)-derived secretory products in fibroblast stimulation after the instillation of long and short asbestos to rat lungs is now investigated. A pure sample of 1 mg long crocidolite (greater than 2.5 mu) induced pulmonary fibrosis in 8 weeks, but secretions of lavaged AM from these lungs did not enhance growth or collagen synthesis in cultured rat lung fibroblasts. In contrast, the same dose of short fibers did not produce pulmonary fibrosis, although AM lavaged from these lungs were increased in number, had more phagocytized fibers, and when incubated, secreted factors that stimulated fibroblasts in culture. When normal AM were exposed to these fiber samples for 24 hours in vitro, greater phagocytosis of particles occurred and each asbestos fiber sample induced secretion of an AM-derived growth factor for cultured fibroblasts. The results indicate that both long and short fibers are capable of inducing AM to secrete fibrogenic factors in vitro, but in vivo, cytokine secretion by AM into the alveolar spaces in response to short fibers is not associated with stimulation of the interstitial fibroblast. In contrast, pulmonary fibrosis after long fiber administration appears unrelated to an AM secretion and is probably caused by fiber penetration into the peribronchiolar tissue, where interstitial macrophage activation may occur over several weeks.

Airway carcinoembryonic antigen concentrations in patients with central lung cancer or chronic bronchitis.

To determine the clinical utility of airway carcinoembryonic antigen (CEA) concentrations to distinguish malignant from inflammatory airway disease in patients undergoing bronchoscopy, we determined CEA concentrations by enzyme immunoassay in bronchial washings recovered in 48 subjects, including 20 patients with central lung cancer, 18 patients with chronic bronchitis, and ten nonsmoking patients with a diagnosis of pneumonia or peripheral granuloma. Concentrations of CEA in bronchial washings were standardized by using the total protein concentration in recovered fluid (CEA/TP). Concentrations of CEA were significantly increased in bronchial washings recovered from both patients with chronic bronchitis and lung cancer compared with patients with pneumonia or granuloma (252 +/- 47 ng/mg and 199 +/- 64 ng/ml vs 62 +/- 11 ng/mg, SEM, p less than 0.005). Airway CEA concentrations in patients with chronic bronchitis were somewhat increased compared with concentrations recovered from a cancer-involved airway (252 +/- 47 ng/ml vs 199 +/- 64 ng/mg, SEM, p less than 0.05). Measurement of airway CEA concentrations is not useful in distinguishing malignant from inflammatory airway disease as airway concentrations of CEA may be markedly increased in patients with both conditions.

Bronchoalveolar lavage in patients with mild and severe rheumatoid lung disease.

The reported prevalence of interstitial lung disease in patients with rheumatoid arthritis has varied from 10% to 50%, yet less than 5% of patients with arthritis develop severe fibrosing interstitial lung disease. This suggests that subclinical disease may not always presage progressive disease. Bronchoalveolar lavage fluid from patients with rheumatoid arthritis and either clinically evident interstitial lung disease or subclinical disease was examined for the presence of factors with a putative role in the development of interstitial fibrosis. Patients with subclinical disease were identified by prospective radiographic and lung function screening of 93 patients with rheumatoid arthritis. Fourteen patients were identified in this manner and an association between subclinical disease and smoking history was noted. Eleven patients with established interstitial lung disease had increased neutrophils (p less than 0.05), collagenase, and type III procollagen N terminal peptide levels (p less than 0.01) in the bronchoalveolar lavage fluid. Preliminary characterisation of the bronchoalveolar lavage collagenase suggested that it originated from neutrophils. Ten patients with subclinical interstitial lung disease underwent bronchoalveolar lavage. Of these, one had increased neutrophils and two had increased collagenase concentrations--abnormalities associated with advanced interstitial lung disease and a poor prognosis. These results suggest that in arthritis patients with evidence of subclinical pulmonary interstitial disease bronchoalveolar lavage might be useful in identifying those who may require careful monitoring in the hope that early treatment will prevent severe fibrosis.

Increased levels of interleukin-1 in bronchoalveolar washings from children with bacterial pulmonary infections.

To investigate its role in pulmonary infections, concentrations of interleukin-1 were measured in 22 bronchoalveolar lavage fluid (BALF) samples from 19 children with cystic fibrosis (CF), and in 13 disease controls by enzyme-linked immunosorbent assay (ELISA) for IL-1 beta and the D10.G4.1 proliferation assay for IL-1 activity. Significantly higher levels of IL-1 beta and IL-1 activity were found in BALF from patients with bacterial pulmonary infections than in those without such infection. There was no significant difference between the levels in patients with CF and pulmonary infections and those in children with bacterial infections complicating other diseases. High performance liquid chromatography showed that most of the IL-1 beta was associated with a molecular weight peak of 17 to 18 kD. Pulmonary inflammation reflected by the number of polymorphonuclear leukocytes (PMN) in the sample correlated significantly with the IL-1 concentration.

Evidence for protein oedema, neutrophil influx, and enhanced collagen production in lungs of patients with systemic sclerosis.

Bronchoalveolar lavage fluid from patients with systemic sclerosis was analysed for evidence of pulmonary vascular leakage, inflammatory cell influx, and enhanced type III collagen synthesis. Eighteen patients with systemic sclerosis and computed tomographic evidence of fibrosing alveolitis were compared with 16 patients with a normal scan. The albumin concentration in lavage fluid was higher in all patients than in normal volunteers. Patients with an abnormal computed tomogram as a group had increased proportions of all inflammatory cell types, whereas those with a normal scan had increased neutrophils only. Increased lavage type III procollagen peptides were found in all patients with an abnormal computed tomogram and eight of those with a normal scan. These results suggest that pulmonary vascular leakage and neutrophil influx may be early pathological features of lung disease in systemic sclerosis and frequently associated with enhanced collagen production. Thus lavage of patients with systemic sclerosis may identify lung inflammation and altered collagen metabolism early in the evolution of fibrosing alveolitis.

Transfer of 99mTc DTPA and bronchoalveolar lavage findings in patients with asymptomatic extrinsic allergic alveolitis.

An investigation was performed to determine whether symptom free patients with previously diagnosed extrinsic allergic alveolitis had signs of inflammation in the lung. Pulmonary clearance of inhaled technetium-99m labelled diethylene triamine penta-acetic acid (DTPA) was measured in seven patients with a history of extrinsic allergic alveolitis but with no symptoms at the time of the study and in 12 control subjects. Monoexponential clearance curves were obtained in all 12 control subjects. In contrast, lung clearance was abnormal in five of the seven patients: biexponential clearance curves were noted in four and an abnormally rapid monoexponential curve in one. Bronchoalveolar lavage was performed in all patients. Fluid from the second and third aliquots showed increased concentrations of albumin and urea in fluids from the patients, suggesting increased plasma leakage through the alveolocapillary membranes. More eosinophils and more eosinophil cationic protein were also found in the lavage fluid from the patients. The trend towards increased numbers of eosinophils in patients with abnormal lung clearance of DTPA suggests that this may be due to a continuing inflammatory reaction. Lung inflammation was also suggested by the fact that less leukotriene B4 was secreted by cultured alveolar macrophages obtained from patients than by control macrophages. It is concluded that symptom free patients with previous extrinsic allergic alveolitis have continuing alveolar disease as shown by lung clearance and lavage findings.

Asbestos exposure results in increased lung procoagulant activity in vivo and in vitro.

Enhanced fibrin deposition is a common histologic finding in fibrotic lung disorders including asbestosis and may be an important mechanism by which fibroblast proliferation is modulated. Asbestos-induced activation of lung interstitial cells may result in enhanced expression of procoagulant activity which contributes to the inflammatory response resulting in subsequent fibrin deposition. The current study examines procoagulant activity in bronchoalveolar lavage fluid from patients with clinically diagnosed asbestosis, patients with asbestos exposure without asbestosis, and normal, control subjects. Results indicated that asbestos exposure resulted in increased lung procoagulant expression in vivo, and furthermore, suggested that both endothelial cells and alveolar macrophages represented lung parenchymal cells which may contribute to this activity. This imbalance in coagulation homeostasis may be important in the regulation of fibrotic responses observed in asbestosis.

An assay for the assessment of lipocortin 1 levels in human lung lavage fluid.

The physiological function of the lipocortins, proteins which are thought to be glucocorticoid-regulated, is unclear. An improved assay for lipocortins might help to elucidate their role. A rapid and specific sandwich enzyme-linked immunosorbent assay (ELISA) for lipocortin 1 with a working range of 1-2000 ng/ml and an interrun coefficient of variation of less than 10% is described and used in this pilot study to quantify human lipocortin 1 for the first time in acellular bronchoalveolar lavage fluid (BALF), and in media conditioned by BAL cells, from control patients and those with pulmonary sarcoidosis. Using this assay a statistically significant relationship, not previously observed in man, has been demonstrated between concentrations of lipocortin 1/ml of BALF and serum cortisol levels (n = 10, rs = 0.6939, P less than 0.05). Although lipocortin 1 levels in acellular BALF were the same in control and sarcoid patients, significantly more lipocortin 1 was released from sarcoid BAL cells in culture (median 21.6, range 8.1-45.4 ng lipocortin/10(6) cells/h in culture) than from control cells (2.5, 1.5-7.6 ng lipocortin/10(6) cells/h in culture). The possible clinical significance of these data is discussed, but remains to be established.

Elevated levels of leukotriene C4 in bronchoalveolar lavage fluid from atopic asthmatics after endobronchial allergen challenge.

Sulfidopeptide leukotrienes have been implicated in the pathogenesis of asthma because of their ability to induce bronchospasm, airways hyperreactivity, and increased mucus production. In the present study, the leukotrienes (LT) C4, D4, and E4 were measured in bronchoalveolar lavage fluid (BALF) before and 5 min after endobronchial allergen challenge in four subject groups: nonatopic nonasthmatic, nonatopic asthmatic, atopic nonasthmatic, and atopic asthmatic. As determined by high performance liquid chromatography (HPLC), after allergen challenge, the predominant sulfidopeptide leukotriene found in BALF from atopic asthmatics was LTC4. Smaller amounts of LTD4 and LTE4 were detectable. The baseline level of leukotrienes in the atopic asthmatics was 64 +/- 18 pg/ml, with measurable levels being found in nine of 11 samples. Atopic nonasthmatics had measurable levels in only one of seven baseline samples, whereas five of six nonatopic subjects had undetectable levels. Allergen challenge in atopic asthmatics resulted in significant increases in LTC4 over prechallenge levels (64 +/- 18 to 616 +/- 193 pg/ml) (p less than 0.01) and over levels in the three control groups after challenge (p = 0.0297). The atopic nonasthmatic group also had detectable leukotriene levels after allergen challenge (88 +/- 32 pg/ml), whereas leukotrienes remained undetectable in five of the six nonatopic samples. For comparison, histamine and the prostanoids prostaglandin D2 (PGD2) and thromboxane B2 (TxB2) were also measured in BALF. The levels of all three of these mediators increased in BALF from atopic asthmatics after allergen challenge. After allergen challenge, the best correlation was found between the levels in BALF for the prostanoids PGD2 and TxB2 (r = 0.88).(ABSTRACT TRUNCATED AT 250 WORDS)

A controlled trial of colchicine to reduce the elastase load in the lungs of cigarette smokers with chronic obstructive pulmonary disease.

Current data suggest that emphysema in smokers is caused at least in part by the unrestrained action of neutrophil elastase on pulmonary tissues. Since colchicine reduces the secretion of enzymes from stimulated neutrophils, we designed a clinical trial to determine if colchicine could reduce the elastase load in the lungs or several putative indicators of elastin destruction. We carried out a prospective, double-blind, randomized, and placebo-controlled clinical trial. Outpatients seeking treatment for chronic obstructive pulmonary disease at the University of Texas Health Center at Tyler who met specific criteria were recruited into the study. A group of 46 cigarette smokers between 45 and 75 yr of age with chronic obstructive pulmonary disease (COPD) were studied. Colchicine or placebo was given orally in disguised capsules, 0.6 mg three times per day. Volunteers were placed on a baseline bronchodilator regimen of Theodur orally and albuterol by inhalation. Blood, urine, and bronchoalveolar lavage fluids were obtained after 1 wk of stabilization. The patients were then randomized and treated for 14 days with colchicine, and the measurements were repeated. Modifications in plasma elastin peptides and neutrophil elastase-generated fibrinopeptide A, urinary desmosines, and bronchoalveolar lavage fluid neutrophils or neutrophil elastase were the indicators of success or failure of the treatment. Pre- and posttreatment measurements in each patient and the difference between colchicine-treated and placebo-treated groups were compared. There were no statistically significant differences in either of the two types of analyses in any of the variables. We conclude that variables related to elastase load in the lungs were not modified by colchicine treatment. If a drug can be identified that is successful in modifying one of these variables, it would then have to be tested in a large-scale clinical trial in which the rate of decline in the FEV1.0 or mortality would be measured. The data presented here may provide useful information about the variability of key measurements of elastase load in the lungs and the breakdown of elastin and may aid investigators in designing similar trials in the future.

Assessment of bronchoalveolar cell and mediator response to isocapnic hyperpnea in asthma.

The purpose of this study was to test the hypothesis that mediators and cells associated with bronchoconstriction or inflammation are locally synthesized and/or released in the airways of asthmatic subjects in response to isocapnic hyperpnea (ISH). Seven atopic, mildly asthmatic subjects were studied. Baseline measurements were reported previously and included forced expiratory volumes, flow rates, bronchoalveolar lavage (BAL), and methacholine reactivity. Approximately 1 yr later, spirometry and BAL were repeated, but BAL was performed immediately after ISH challenge. As indices of inflammation, BAL measurements were made of eosinophils, neutrophils, epithelial cells, leukotrienes B4, C4, D4, and E4, prostaglandins D2, E2, and F2 alpha, thromboxane B2, histamine, and total protein. Compared with baseline, ISH was associated with higher BAL concentrations of the following: leukotriene B4 (10 versus 121 pg/ml, p = 0.02), leukotrienes C4/D4/E4 (46 versus 251 pg/ml, p = 0.02), eosinophils (0.8 versus 2.2%, p = 0.04), and epithelial cells (2.1 versus 6.1%, p = 0.05). Trends toward significant increases were seen in BAL concentrations of neutrophils and prostaglandin D2. No statistically significant increases were found in BAL measurements of total protein, histamine, prostaglandins E2 or F2 alpha, thromboxane B2, lymphocytes, or macrophages. The magnitude of the response to ISH, as measured by change in FEV1, did not correlate with BAL levels of cells or mediators. This study indicates that ISH, even in mildly asthmatic subjects, is associated with airway increases in a spectrum of bronchoactive mediators and inflammatory cells, supporting the observations of others that antagonists of a single mediator are unlikely to have major clinical effectiveness in ISH or exercise-induced asthma.

Modulation of pulmonary eicosanoid metabolism following exposure to sulfuric acid.

Eicosanoids (arachidonic acid metabolites) are potent biological mediators. Modulation of their metabolism by air pollutants may be a possible factor in the pathogenesis of environmentally related lung disease. Sulfuric acid (H2SO4) aerosols are components of ambient air in many areas. Rabbits were exposed to H2SO4 (0.3 microns) at 250, 500, or 1000 micrograms/m3 for 1 hr/day for 5 days. They were then euthanized, the lungs lavaged, and eicosanoid analyses performed by radioimmunoassay of acellular lavage fluid. An exposure-concentration-dependent decrease in levels of prostaglandins E2 and F2 alpha and thromboxane B2 was found; no change in leukotriene B4 was observed. Tracheal explants exposed to acidic environments in vitro also showed reduced production of PGE2, PGF2 alpha, and TxB2. Incubation with sodium sulfate (Na2SO4) showed no effect of the sulfate ion (SO4(2-)). This study, the first to examine eicosanoid production after in vivo exposure to pure H2SO4 droplets, indicates that such exposure can modulate arachidonic acid metabolism, and that this is likely due to the deposition of hydrogen ion (H+) on target tissue.