The origin of water and urea sampled at bronchoalveolar lavage in asthmatic and control subjects

Metabolic hormones, apolipoproteins, adipokines, and cytokines in the alveolar lining fluid of healthy adults: compartmentalization and physiological correlates

Objectives

Our current understanding of hormone regulation in lung parenchyma is quite limited. We aimed to quantify a diverse array of biologically relevant protein mediators in alveolar lining fluid (ALF), compared to serum concentrations, and explore factors associated with protein compartmentalization on either side of the air-blood barrier.

Research Design and Methods

Participants were 24 healthy adult non-smoker volunteers without respiratory symptoms or significant medical conditions, with normal lung exams and office spirometry. Cell-free bronchoalveolar lavage fluid and serum were analyzed for 24 proteins (including enteric and metabolic hormones, apolipoproteins, adipokines, and cytokines) using a highly sensitive multiplex ELISA. Measurements were normalized to ALF concentrations. The ALF:serum concentration ratios were examined in relation to measures of protein size, hydrophobicity, charge, and to participant clinical and spirometric values.

Results

ALF measurements from 24 individuals detected 19 proteins, including adiponectin, adipsin, apoA-I, apoA-II, apoB, apoC-II, apoC-III, apoE, C-reactive protein, ghrelin, glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, insulin, leptin, monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, resistin, and visfatin. C-peptide and serpin E1 were not detected in ALF for any individual, and IL-6, IL-10, and TNF-alpha were not detected in either ALF or serum for any individual. In general, ALF levels were similar or lower in concentration for most proteins compared to serum. However, ghrelin, resistin, insulin, visfatin and GLP-1 had ALF concentrations significantly higher compared to serum. Importantly, elevated ALF:serum ratios of ghrelin, visfatin and resistin correlated with protein net charge and isoelectric point, but not with molecular weight or hydrophobicity.

Conclusions

Biologically relevant enteric and metabolic hormones, apolipoproteins, adipokines, and cytokines can be detected in the ALF of healthy individuals. For the proteins measured, charge may influence trafficking and compartmentalization to the alveolar airspace more than molecular weight or hydrophobicity. These data may have implications for homeostasis and drug delivery to the lung.

Description of an Automated Method for Urea Nitrogen Determination in Bronchoalveolar Lavage Fluid (BALF) of Neonates and Infants

Bronchoalveolar lavage (BAL) partially recovers both the instilled saline and the alveolar fluid, so-called epithelial lining fluid (ELF), but a correction for the dilution due to the BAL technique itself is needed to know the amount of recovered ELF. In this regard, urea nitrogen may be useful and has been proposed to calculate ELF. The aim of the present study was to develop and validate a new method to measure urea nitrogen in BAL fluid (BALF). We used 19 BALF samples obtained from neonates and infants with different respiratory conditions. The urea nitrogen assay was carried out on Cobas c311 analyzer (Roche Diagnostics). A validation study shows that the method is perfectly linear (R(2) = 0.999), sensitive (limit of detection = 0.055 mg/dL; limit of quantification = 0.16 mg/dL), repeatable (low = 0.15 ± 0.02, 13.3%; high = 1.80 ± 0.02, 1.1%), reproducible (low = 0.14 ± 0.02, 14.2 %; high = 1.76 ± 0.04, 2.2 %) with accuracy ranging between 93-96%. Our results support the robustness of validated procedure since the described method appears simple, precise, rapid, and suitable for routine analysis. Thus, it may be used to correct concentration of various noncellular BAL components and calculate their ELF amounts in neonates and infants.

Bacterial ventilator-associated pneumonia: bronchoalveolar lavage results are not influenced by dilution

OBJECTIVE

This study was designed to determine if bronchoalveolar lavage (BAL) quantitative culture results can be used confidently for the diagnosis of bacterial ventilator-associated pneumonia (VAP) without taking dilution into account.

DESIGN

Prospective observational cohort study.

SETTING

A 12-bed medical ICU in a teaching hospital.

PATIENTS

A total of 241 BAL (three 50-mL aliquots) were performed in 127 patients presenting a suspicion of VAP.

INTERVENTIONS

All consecutive adults who were ventilated more than 48 h were included if VAP was clinically suspected. A dilution factor, k, was developed according to the formula: dilution factor k = concentration of urea in plasma/concentration of urea in lavage fluid recovered. Using this dilution factor, the quantitative bacterial counts were interpreted accordingly with a corrected positive threshold at 10(5) colony forming unit (CFU) mL(-1).

MEASUREMENTS AND RESULTS

Eighty-nine BAL with at least one micro-organism > or = 10(4) CFU mL(-1) were identified (37%). In 176 BAL (73%), k ranged from 10 to 100. Median k was 24.4 (9.7-40.2) in VAP group and 24.6 (13.1-57.8) in patients without pneumonia (NS). Among the 25 BAL with micro-organism counts of 10(4) CFU mL(-1), 3 had a dilution factor lower than 10, resulting in corrected counts below the threshold of 10(5) CFU mL(-1). Two out of 15 patients with micro-organism counts of 10(3) CFU mL(-1) had corrected micro-organism counts of 10(5) CFU mL(-1). Finally, only five BAL (2.1%) were misclassified when the dilution correction factor was applied.

CONCLUSIONS

Using urea as dilution factor, we showed that BAL dilution variations did not alter the interpretation of BAL quantitative bacterial culture when administrating three aliquots of 50 mL of saline.

Comparison of the antioxidant status in tracheal and bronchoalveolar epithelial lining fluids in recurrent airway obstruction

REASONS FOR PERFORMING STUDY

Following a period of airway inflammation the clearance of inflammatory cells along the mucociliary escalator may impose a considerable oxidant load on the trachea.

OBJECTIVES

To determine the degree of oxidative stress in tracheal epithelial lining fluid (ELF) in comparison to that present in peripheral airways after an acute exposure to organic dust.

METHODS

Tracheal wash fluid and bronchoalveolar lavage fluid (BALF) were collected for cytology and antioxidant analyses from 6 recurrent airway obstruction (RAO)-affected horses and 6 healthy control horses before and after stabling on straw bedding for 24 h.

RESULTS

In RAO-affected horses, organic dust exposure resulted in a significant decrease in ascorbic acid concentration in tracheal ELF (P<0.0001), which was greater than the decrease in bronchoalveolar ELF (P = 0.0003). The percentage decrease in tracheal ELF ascorbic acid correlated with the percentage decrease in bronchoalveolar ELF ascorbic acid (r = 0.76; P = 0.004) following exposure.

CONCLUSIONS

Acute organic dust exposure results in significant antioxidant depletion in the trachea, which may reflect inflammation and oxidative processes in peripheral airways.

POTENTIAL RELEVANCE

Further work is required to evaluate the role of ascorbic acid depletion in the pathogenesis of RAO.

Chemokines and inflammation in the nasal passages of infants with respiratory syncytial virus bronchiolitis

This study measured chemokines in nasal lavage fluids (NLF) from infants with respiratory syncytial virus (RSV) bronchiolitis, defined by lung hyperinflation and wheezing. Comparison was made to RSV-positive infants without bronchiolitis and RSV-negative infants with acute respiratory illnesses. RSV-positive illnesses were associated with increased epithelial shedding, increased RANTES/protein ratios, and increased IL-8/protein ratios in NLF compared to RSV-negative illnesses. Among RSV-positive infants, bronchiolitics had greater total cell counts and percentage epithelial cells in NLF than nonbronchiolitics. Bronchiolitics also had roughly twice the NLF RANTES/IL-8 ratio than nonbronchiolitics (P =.043). Semiquantitative reverse transcriptase-polymerase chain reaction of nasal epithelium suggested similar RANTES/IL-8 ratio increases among bronchiolitics. A more mildly affected, RSV-positive outpatient population showed none of these differences. We conclude that RSV bronchiolitis is associated with a shift toward relatively more RANTES in nasal secretions of infants sick enough to require hospitalization, and mucosal epithelium may contribute to this process. Similar processes in the lower airways may enhance inflammation due to RANTES-responsive cell types and affect clinical manifestations.

Enzyme activities, protein content and cellular variables in the pulmonary epithelial lining fluid in selected healthy pigs

Reference values of cellular and non-cellular components in the bronchoalveolar lavage fluid (BALF) were established from the BALF specimens obtained from 52 healthy pigs. Using urea as an endogenous marker of dilution, the reference values in the epithelial lining fluid (ELF) were calculated: total cell count 2.71 x 10(9) - 56.49 x 10(9) litre(-1) ELF, alveolar macrophages 2.02 x 10(9) - 49.91 x 10(9) litre(-1) ELF, lymphocytes 0.10 x 10(9) - 4.74 x 10(9) litre(-1) ELF, polymorphonuclear neutrophils 0.01 x 10(9) - 3.48 x 10(9) litre(-1) ELF, protein 0.10 - 13.13 g litre(-1) ELF, lactate dehydrogenase 127-1843 Units litre(-1) ELF, and alkaline phosphatase 86-994 Units litre(-1) ELF. The problems of quantification of BALF components are discussed and a standardized lavage protocol in swine is described, which is essential for the interpretation of diagnostic findings and for the comparison of different BALF specimens.

Chemokines in nasal secretions of normal adults experimentally infected with respiratory syncytial virus

The goal of this study was to determine time courses of upregulation of several chemokines in nasal secretions after inoculation of human subjects with a low dose of live respiratory syncytial virus (RSV). Healthy, nonsmoking young adults were admitted to an inpatient clinical research unit. After baseline studies, subjects were nasally inoculated with approximately 10(3) plaque-forming units of RSV (strain A2), followed by daily nasal lavages. Nasal lavage fluid (NLF) was assayed for chemokines by specific ELISA. Of 10 subjects inoculated with RSV, 3 developed clinical symptoms of upper respiratory infection and also shed virus. Among infected subjects, there was a transient postinoculation increase in interleukin-8 (IL-8) in NLF to an average of 2.7-fold compared to baseline, followed by a prolonged increase (maximum mean 5.4-fold) during virus shedding. RANTES, MIP-1alpha, and MCP-1 all increased during virus shedding only (maximum mean increases of 5.3-fold, 13-fold, and 7.2-fold, respectively). Semiquantitative RT-PCR in brushed nasal epithelial cells on day 6 after inoculation suggested upregulation of RANTES, but not IL-8, mRNA during virus shedding. We conclude that chemokines IL-8, RANTES, MIP-1alpha, and MCP-1 are all increased in nasal secretions in human RSV infection at the time of virus shedding and symptomatic illness and that the epithelium lining the nasal turbinate contributes to the increase in RANTES.

Validity of markers of dilution in small volume lung lavage

Definitive analysis of solute concentrations in lung lavage fluid involves the use of a marker of dilution to correct for variable recovery of epithelial lining fluid (ELF), but the question of the most appropriate dilutional marker remains unresolved. In lavage fluid collected from infants with lung disease and healthy control subjects, we examined ELF concentration of protein, albumin, sphingomyelin (SM), and IgA secretory component (SC), and critically appraised the relative validity of SC and urea as dilutional markers in the context of lung infection and lung injury. Protein, albumin, and SM were found not to be valid dilutional markers, as their ELF concentration varied significantly between the diseased, recovering, and normal lung. Differences in concentration were noted in both tracheal aspirate samples (TA, 4 x 0.5 ml) and nonbronchoscopic bronchoalveolar lavage fluid (NB-BAL, 3 x 1 ml/kg), but were not uniform (e.g., TA-disease versus control: albumin 2.8 versus 0.68 mg/ml, SM 45 versus 16 microgram/ml, both p < 0.05; NB-BAL-disease versus recovery: protein 8.1 versus 4.8 mg/ml, albumin 2.9 versus 1. 4 mg/ml, both p < 0.05). Overall, SC concentrations in ELF were not different between the diseased and normal lung, but in the NB-BAL samples, significantly higher SC concentration was noted in viral bronchiolitis and pneumonia than in noninfective lung diseases. No clear evidence of additional influx of urea into lavage fluid in association with epithelial disruption was found in the diseased lung. Comparative analysis of SC and urea revealed no difference in TA samples, but in NB-BAL specimens, urea best standardized the lavage concentration of surfactant indices to correspond to the degree of lung dysfunction as indicated by oxygenation index. We conclude that SC and urea, but not protein, albumin, or SM, are valid dilutional markers with which to estimate ELF recovery during small volume lung lavage. Urea appears a more appropriate choice in return fluid derived from the distal tracheobronchial tree, and SC should not be used in the context of lung infection.

A double-blind study on the effect of inhaled corticosteroids on plasma protein exudation in asthma

Plasma protein exudation into the airways is an important pathophysiological event in asthma. The effect of 12 wk of treatment with inhaled fluticasone propionate (FP; 250 microgram twice a day) or salbutamol (Sb; 400 microgram twice a day) on plasma protein leakage was compared in a double-blind, randomized parallel-group study of 30 patients with asthma. Primary outcomes were plasma protein leakage and size selectivity of the blood-airway lumen barrier, cell differentials in BAL fluid, and bronchial responsiveness to histamine (PC20histamine). Two independent procedures to account for the effect of variable dilution of BAL on the levels of albumin (Alb) and alpha2-macroglobulin (A2M) in BAL fluid consisted of correction based on urea levels and on the application of the relative coefficient of excretion [RCE = ([A2M] in BAL fluid/[A2M] in serum)/([Alb] in BAL fluid/[Alb] in serum)]. In the FP group a significant decrease was found in the A2M level and the RCE, and in the percentage of eosinophils in BAL fluid. The PC20histamine increased significantly (mean increase, 2.4 doubling doses), whereas PC20histamine decreased in the Sb group. Differences between groups were significant except for the decrease in eosinophils. We conclude that 12 wk of FP (250 microgram twice a day) decreased the permeability of the blood-airway lumen barrier, in particular for high molecular weight proteins.

Compromised antioxidant status and persistent oxidative stress in lung transplant recipients

Oxidative stress may be a key feature, and hence important determinant, of tissue injury and allograft rejection in lung transplant recipients. To investigate this, we determined the antioxidant status (urate, ascorbate, thiols and alpha-tocopherol) and lipid peroxidation status (malondialdehyde) in bronchoalveolar lavage (BAL) fluid and blood serum of 19 consecutive lung transplant recipients 2 weeks and 1, 2, 3, 6, and 12 months post-surgery. BAL fluid and blood samples from 23 control subjects and blood from 8 patients two days before transplantation were obtained for comparison. Before surgery, the antioxidant status of patients was poor as serum ascorbate and total thiol concentrations were significantly (p < 0.05) lower than control subjects. Two weeks post-surgery, ascorbate and total thiol concentrations were still low and urate concentrations had fallen compared to control subjects (p < 0.01). At this time, BAL fluid urate concentration was higher (p < 0.01), ascorbate concentration was lower (p < 0.01) and reduced glutathione concentrations were similar to control subjects. MDA, a product of lipid peroxidation, was higher (p < 0.01) in both BAL fluid and serum obtained from transplant patients compared to control subjects. During the first 12 months post-surgery, little improvement in antioxidant status or extent of lipid peroxidation was seen in transplant recipients. Regression analysis indicated no difference in serum or BAL fluid antioxidant status in patients with acute rejection compared to those without. In conclusion, lung transplant recipients have a compromised antioxidant status before surgery and it remains poor for at least the first year following the operation. In addition, these patients have elevated MDA concentrations in both their lung lining fluid and blood over most of this time. Oxidative stress is not, however, a sufficiently sensitive endpoint to predict tissue rejection in this group.

Surfactant protein levels in severe respiratory syncytial virus infection

Infection with respiratory syncytial virus (RSV) is a common cause of respiratory disease in infancy. Surfactant phospholipids have been shown to be reduced in severe RSV infection. Reduction in surfactant proteins might also contribute to the pathogenesis of this disease. We investigated daily levels of surfactant proteins in bronchoalveolar lavage (BAL) fluid from 18 ventilated infants with RSV infection (median age 3.1 mo) and in a control group of 16 ventilated surgical patients (median age 0.4 mo). Surfactant proteins were measured by ELISA, total protein by the Lowry method. Surfactant protein A (SP-A) was reduced in BAL fluid from children with RSV infection (median 5.6 micrograms/ml; range 0.6 to 151.9 micrograms/ml) compared with control samples (median 9.0 micrograms/ml; range 0.5 to 139.6 micrograms/ml, p = 0.0368). Surfactant protein B (SP-B) was lower in the RSV group (median 12.0 ng/ml; range 0 to 60. 8 ng/ml) than in control patients (median 118.1 ng/ml; range 0 to 778.2 ng/ml, p < 0.0000). Surfactant protein D (SP-D) was also reduced in the RSV group (median 130.3 ng/ml; range 0 to 1,486.0 ng/ml) versus median 600.4 ng/ml; range 0 to 1,869.0 ng/ml, p < 0. 0000. Total protein levels were higher in the RSV group (median 0.49 mg/ml; range 0.13 to 2.46 mg/ml versus median 0.36 mg/ml; range 0.07 to 1.65 mg/ml, p = 0.0079). The median value of SP-A was significantly lower in the initial sample (2.3 micrograms/ml) than in the final one (6.0 micrograms/ml). However, no significant correlation was found between surfactant protein concentrations and disease severity measured by arterial alveolar oxygen ratio. We conclude that alterations in surfactant protein concentrations are present in severe RSV infection and speculate that these may contribute to the abnormalities of lung function seen in this condition.

Cromolyn sodium prophylaxis inhibits pulmonary proinflammatory cytokines in infants at high risk for bronchopulmonary dysplasia

An imbalance of proinflammatory cytokines such as TNF-alpha, IL-1 beta, and the neutrophil chemotactic factor IL-8 and inhibitors (e.g., soluble TNF receptors and IL-1ra) in the lung during the first week of life may contribute to prolonged pulmonary inflammation and fibrosis in bronchopulmonary dysplasia (BPD). Disodium cromoglycate (DSCG) has anti-inflammatory effects in asthma, a disease with many similarities with BPD. In a prospective, randomized, blinded study, we examined whether early DSCG therapy inhibits proinflammatory cytokines in infants at risk for BPD. Twenty-six infants who were identified as high risk (> or = 75% probability) for oxygen-dependency at 28 d by a 12-h predictive score and survived 48 h were randomized to nebulized DSCG 20 mg (n = 13) or 2 cc NS (control, n = 13) every 6 h from Day 3 to Day 28. Lung lavage was collected on Day 3 (pre-study) and Day 7 and analyzed for cell count and differential and TNF-alpha, sTNFR1, sTNFR2, IL-1 beta, IL-1ra, and IL-8 concentrations. The groups' pre-study lavage cytokine concentrations were similar, but TNF-alpha and IL-8 concentrations were 3.6- and 4.9-fold lower in the DSCG group on Day 7 compared with levels in the control group. Soluble TNF receptors were unaffected by DSCG. There was a trend towards lower IL-1 beta levels in DSCG-treated infants on Day 7, but IL-1ra levels were unaffected by DSCG therapy. Three control subjects, but no DSCG-treated infants, died during the study period (p = 0.07). There were no significant differences between survivors of the two groups for oxygen-dependency at 28 d (100% control subjects; 85% DSCG). These results suggest that nebulized DSCG may exert an anti-inflammatory effect in the lungs of infants < or = 1,000 g at risk for BPD.

Bronchoalveolar lavage in asthma research

A great deal of information about the pathophysiology of asthma and its treatment have been obtained through the use of bronchoalveolar lavage (BAL), especially in combination with airway biopsies. The introduction of highly sophisticated methods for examining BAL aspirate, including fluorocein activated cell scanning (FACS) analysis and molecular biology techniques has emphasized the potential power of this method of airway investigation. For those contemplating the use of BAL in asthma research programmes, we hope that this review will provide a useful insight into the current state of knowledge about the technique and its application, and that it will provide a solid platform for study design.

Bronchoalveolar lavage or oropharyngeal cultures to identify lower respiratory pathogens in infants with cystic fibrosis

As collections of lower respiratory tract specimens from young children with cystic fibrosis (CF) are difficult, we determined whether oropharyngeal cultures predicted lower airway pathogens. During 1992-1994, 75 of 90 (83%) infants with CF diagnosed by neonatal screening had 150 simultaneous bronchoalveolar lavage (BAL) and oropharyngeal specimens collected for quantitative bacterial culture at a mean age of 17 months (range, 1-52). Ten children undergoing bronchoscopy for stridor served as controls. Total and differential cell counts and interleukin-8 concentrations were measured in BAL fluid. A subset of bacterial pathogens were typed by pulsed field gel electrophoresis. A non-linear relationship with inflammatory markers supported a diagnosis of lower airway infection when > or = 10(5) colony-forming units/ml were detected. This criterion was met in 47 (31%) BAL cultures from 37 (49%) children. Staphylococcus aureus (19%), Pseudomonas aeruginosa (11%), and Hemophilus influenzae (8%) were the major lower airway pathogens. In oropharyngeal cultures, S. aureus (47%), Escherichia coli (23%), H. influenzae (15%), and P. aeruginosa (13%) predominated. The sensitivity, specificity, and positive and negative predictive values of oropharyngeal cultures for pathogens causing lower respiratory infections were 82%, 83%, 41%, and 97%, respectively. When there was agreement between paired oropharyngeal and BAL cultures, genetic fingerprinting showed some strains of the same organism were unrelated. We conclude that oropharyngeal cultures do not reliably predict the presence of bacterial pathogens in the lower airways of young CF children.

Potential role of interleukin-1 in the development of bronchopulmonary dysplasia

Increased activities of inflammatory mediators unopposed by their inhibitors contribute to chronic lung injury and impaired healing in BPD. The deleterious effects of IL-1 beta, a cytokine involved in inflammation and host defense, are blocked by IL-1 receptor antagonist (IL-1Ra). We proposed that an imbalance of IL-1 beta and its inhibitors may contribute to the development of BPD. To determine the relative antigen concentrations of IL-1 beta and IL-1Ra and functional IL-1 activity in lung lavage of infants at risk for BPD, lung lavage was serially obtained from 1 to 28 days from 17 infants with evolving BPD, 13 infants with self-limited RDS, and 6 controls ventilated for nonpulmonary reasons. Overall, there was a high correlation between IL-1 beta antigen concentration and IL-1 activity (r = 0.82, p = 0.0001). There were no significant differences among the groups for lung lavage variables on day 1. However, in infants who developed BPD, IL-1 beta antigen concentration and IL-1 activity increased 16- and 61-fold, respectively, during the first week. IL-1Ra remained relatively unchanged during the first month. IL-1 beta/IL-1Ra antigen ratio was significantly higher on days 5 (median 0.024) and 7 (median 0.025) compared with day 1 (median 0.004), p < 0.05. These results suggest that a relative imbalance of IL-1 beta and IL-1Ra may contribute to prolonged inflammation in BPD.

Adjustment of bronchoalveolar lavage volume to body weight in children

To define the amount of epithelial lining fluid (ELF) that is recovered during bronchoalveolar lavage (BAL) in the pediatric age group, we measured albumin and urea concentrations in serum and BAL fluid (BALF) of 37 children aged 3-15 years without bronchopulmonary disease. The children were studied while undergoing elective surgery for non-pulmonary illnesses using a BAL protocol adjusted to body weight. ELF increased with age in proportion to increases in lavage volume. When corrected for the child's weight, approximately 20 mu l ELF/kg body weight were recovered throughout the age range. ELF derived by determining albumin or urea concentrations in BALF were significantly correlated; however, considerable variability was observed in older children when the urea method was used. This was likely due to the increase in dwell time that is known to affect urea concentrations in BALF. In children ELF/100 ml BALF was higher than in adults, suggesting a greater permeability of the alveolar membrane in children. These data show that a BAL protocol adjusted to body weight will yield constant fractions of ELF in children aged 3-15 years. These results should facilitate the comparison of BALF constituents in children of different age groups.

Glutathione metabolism in newborns: evidence for glutathione deficiency in plasma, bronchoalveolar lavage fluid, and lymphocytes in prematures

Respiratory distress in premature newborns is associated with deficiency of surfactant in the bronchoalveolar lining fluid; this may be influenced by a local deficiency of antioxidants. Severe L-buthionine-S,R-sulfoximine-induced depletion of glutathione (GSH, a major antioxidant) in rodents is associated with lung type 2 cell lamellar body damage and decreased concentrations in lung and bronchoalveolar lavage fluid (BALF) of phosphatidyl choline (a major component of surfactant). At birth, prematurely born newborns (30-34 weeks) had lower peripheral venous plasma GSH concentrations than term (> 36 weeks) babies; these levels decreased further with increasing prematurity (< 27 weeks, with respiratory distress). On day 2, the peripheral venous plasma GSH concentrations reached a nadir, and the lowest levels were found in the most premature newborns. Lymphocyte GSH concentrations were lowest on day 2 and day 7, and in prematures (< 27 weeks, with respiratory distress) remained below adult lymphocyte GSH levels for at least 4 weeks. At birth, prematures (< 27 weeks, with respiratory distress) had a central plasma arterio-venous (A-V) GSH gradient across the lung (an estimate of lung uptake of GSH) of 0.72 +/- 0.15 (mean +/- SD) mumol/L; on day 2, the A-V gradient did not change significantly (0.49 +/- 0.09 mumol/L). At birth, these prematures had markedly decreased BALF GSH concentrations (compared with adult levels), and they were not significantly changed during the first 4 weeks of life. These results suggest that GSH deficiency is present in prematures and that it increases with the degree of prematurity. At birth, GSH deficiency will compromise the lungs' defense against oxidative stress injury. Oxidative stress is likely to increase if hyperoxic treatment is given for respiratory distress in these infants.

Kinetic retrieval of eosinophil cationic protein, hyaluronan, secretory IgA, albumin, and urea during BAL in healthy subjects

Determination of absolute concentrations of various soluble components of the epithelial lining fluid (ELF) may be valuable to estimate inflammatory activities within the underlying lung tissue. Internal standards may then be used as markers of dilution of bronchoalveolar lavage (BAL). The aim of this study was to determine whether different dwell times would affect the relationship between the concentrations of any of the three potential internal standards (secretory IgA [SIgA], albumin, and urea), and the concentrations of two potential markers of inflammation (eosinophil cationic protein [ECP] and hyaluronan [HA]) in BAL. A series of aliquots of BAL fluid were aspirated every 60 s up to 8 min after a bolus instillation of saline solution in 20 healthy subjects (10 smokers). The BAL concentrations of albumin and urea increased with time, consistent with continuous diffusion from the body water pool, absorption of the BAL fluid, or both. The rate constant of diffusion was 1,000 times higher for urea than for albumin (3.38 x 10(-1) and 3.64 x 10(-4), respectively), reflecting the difference in molecular weights, and in agreement with the notion that albumin and urea appeared in BAL fluid by a rate-limited procedure related to osmotic transfer. Biexponential increases of SIgA were recorded, suggesting a two-compartmental origin of this compound, normally located to mucosal membranes and presumed to be dissolved in ELF. Time-dependent increases in BAL fluid of HA also were recorded, but on the other hand, the ECP concentrations tended to level off after an initial increase, suggesting that the bulk of ECP appeared in BAL by a nonosmotic mechanism. We conclude that the kinetics of these three internal standards in BAL fluid differs greatly from each other and from the kinetics of the two selected markers of inflammation. Consequently, internal standards for determination of absolute concentrations of markers of inflammation in ELF should be carefully selected because of the requirement of matched kinetics of the markers.

Increase in interleukin-8 and soluble intercellular adhesion molecule-1 in bronchoalveolar lavage fluid from premature infants who develop chronic lung disease

Interleukin-8 (IL-8), soluble intercellular adhesion molecule-1 (sICAM), elastase and neutrophils were assessed in bronchoalveolar lavage fluid from nine infants who developed chronic lung disease (CLD) after respiratory distress syndrome (RDS), seven who had recovered from RDS, and in four control infants. IL-8, sICAM, elastase and neutrophils in bronchoalveolar lavage fluid were increased in the CLD group, the differences being most pronounced at 10 days of age. When babies with and without CLD were compared at 10 days of age, bronchoalveolar lavage fluid from the babies with CLD had significantly increased IL-8 (114.0 vs 12.7 ng/ml), sICAM (19.0 vs 1.1 micrograms/ml), elastase (6.9 vs 0.9 micrograms/ml) and neutrophils (1.9 vs 0.4 x 10(9)/l). In serum the increased concentration of IL-8 observed at birth in the CLD (247 pg/ml) and RDS (192 pg/ml) groups decreased over three weeks to the concentrations observed in the controls (< 70 pg/ml). Persistent inflammation could be a major contributory factor in the development of CLD.

Bronchoalveolar lavage fluid endotoxin elevation in human single lung transplant recipients during rejection

Endotoxin has been implicated as an aetiological factor in liver transplant rejection and acute graft-versus-host disease. To investigate the role of endotoxin in human single lung transplant rejection we measured the level of endotoxin in bronchoalveolar lavage (BAL) fluid from six subjects at baseline and during rejection, which was defined histologically from transbronchial biopsy. Differential cell counts of BAL fluid cells, the levels of protein and albumin in BAL fluid, and serum albumin levels were also examined. BAL fluid albumin to serum ratio was calculated to evaluate alveolar-capillary leakage. A significant elevation of BAL fluid endotoxin with rejection compared with baseline was observed. Standardizing endotoxin levels to BAL fluid volume, protein, or albumin were all of similar significance. Examination of BAL fluid cell population revealed a significant elevation in the percentage of lymphocytes with rejection. No significant difference between BAL fluid protein levels, BAL fluid albumin levels. BAL fluid albumin to protein ratio, serum albumin levels, or BAL fluid albumin to serum albumin ratio was seen with rejection. We conclude that BAL fluid endotoxin levels increase during lung rejection, endotoxin levels can be accurately standardized to millilitres of BAL fluid, and abnormal alveolar-capillary leakage does not appear to account for the increased BAL fluid endotoxin.

Protein content in bronchoalveolar lavage fluid of patients with asthma and control subjects

BACKGROUND

Secretory component (SC), Clara cell protein (CC10) and to some extent, IgM are proteins locally synthetized in airways. Albumin, alpha 2-macroglobulin and alpha 1-antitrypsin are mainly plasma proteins. In patients with asthma, blood proteins may occur in greater amounts in bronchoalveolar lavage fluid (BALF) than in control subjects because of plasma extravasation. These proteins were measured in BALF to define markers of local synthesis and plasma exudation.

METHODS

Twenty-four patients with asthma (mean age, 40 +/- 3.1 years) and 24 control subjects (mean age, 29 +/- 11 years) were tested. Five aliquots of saline solution (50 ml) were instilled, and the recovered BALF was stored. Clara cell protein was measured by a sensitive immunoassay technique based on the agglutination of latex particles. SC, immunoglobulins, alpha 2-macroglobulin, alpha 1-antitrypsin, and albumin were measured by an immunoradiometric assay. Protein concentrations were normalized to albumin.

RESULTS

In BALF from patients with asthma there was a significant increase in alpha 2-macroglobulin and IgM and a significant decrease of SC, alpha 1-antitrypsin, and Clara cell protein compared with control subjects. Also, the ratio to albumin was significantly increased for alpha 2-macroglobulin and IgM and decreased for SC. There was no correlation between the severity of asthma and the amount of proteins.

CONCLUSIONS

BALF protein content is significantly different in patients with asthma and control subjects, for proteins produced locally and derived from plasma.

Comparative bronchoalveolar concentrations of ciprofloxacin and lomefloxacin following oral administration

In a comparative study, the concentrations of two fluoroquinolone antimicrobials, ciprofloxacin and lomefloxacin, were measured in serum, bronchial mucosal biopsies, epithelial lining fluid (ELF) and alveolar macrophages (AM). Thirty-four subjects received either ciprofloxacin 250 mg b.d. (17 subjects) or lomefloxacin 400 mg o.d. for 4 days prior to sampling by bronchoscopic bronchial biopsy and bronchoalveolar lavage. Both ciprofloxacin and lomefloxacin showed favourable accumulation in the sites of infection with bronchial biopsy concentrations of 1.6 and 1.7 times those of serum respectively; ELF concentrations of 2.1 and 1.9 times serum; and AM concentrations of 11.8 and 20.1 times serum respectively. The MIC90 for most of the common chest pathogens was reliably exceeded by both agents except for that of Streptococcus pneumoniae.

Adenosine in bronchoalveolar lavage fluid in asthma

The inhalation of nebulized adenosine causes bronchoconstriction in asthmatics. In order to explore whether endogenously produced adenosine may contribute to the pathophysiologic aspects of asthma, we measured adenosine concentrations in bronchoalveolar lavage (BAL) fluid in seven subjects with asthma, eight asymptomatic cigarette smokers, and eight normal subjects. The mean concentration of adenosine in BAL fluid from the normal subjects was 0.72 +/- 0.16 microM. Subjects with asthma and cigarette smokers had significantly increased concentrations of adenosine in BAL fluid, 2.55 +/- 0.50 and 1.89 +/- 0.50 microM, respectively. Corrected for the dilution that occurs as a result of the lavage procedure, mean epithelial lining fluid adenosine concentrations were 60 +/- 13 microM in normal subjects, 193 +/- 58 microM in asthmatics, and 155 +/- 56 microM in smokers. Adenosine concentrations were positively correlated with the protein content of the lavage fluid (r = 0.79). Inhalation of nebulized adenosine in the subjects with asthma provoked a 20% reduction in lung function at concentrations 4- to 195-fold higher than was present in the epithelial lining fluid of the same individuals. The presence of increased BAL adenosine concentrations in asthmatics and in cigarette smokers suggests that adenosine may be a nonspecific marker for inflammation in the lung. The demonstration of physiologically relevant concentrations of adenosine in airway fluids of subjects with bronchial hyperreactivity to inhaled adenosine provides evidence for a role of endogenous adenosine in provoking bronchoconstriction in asthma.