Bronchoalveolar lavage as a research tool

Endotracheal suctioning of the neonate: comparison of two methods as a source of mucus material for research

Endotracheal suctioning in the neonatal intensive care setting is a routine procedure performed to maintain patency of the airway in ventilated infants. Harvested material can also be a source of mucus for research into neonatal respiratory disorders. We aimed to investigate whether the composition of material obtained by our clinically preferred technique of dry shallow suctioning differed significantly from that obtained with saline lavage and deep suctioning. Eleven pairs of dry and saline lavage aspiration samples were compared for neutrophil enzyme myeloperoxidase, total and active alpha(1)-antitrypsin, alpha(1)-antitrypsin complexed with elastase, and secretory leukoprotease inhibitor. Even though individual values of each analyte, expressed per gram of albumin, varied over at least a fivefold range, there was no difference between mean values of dry and lavage samples for any of the constituents. We conclude that the yield of material for research obtained by dry shallow suctioning is adequate and the quality at least as satisfactory as that provided by saline lavage.

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.

Early production of macrophage inflammatory protein-1 alpha occurs in respiratory distress syndrome and is associated with poor outcome

Although progression to pulmonary fibrosis in preterm infants with respiratory distress syndrome (RDS) is related to the inflammatory response, the nature of this response remains controversial. We have therefore performed sequential bronchoalveolar lavages in 30 infants with RDS (13 of whom developed bronchopulmonary dysplasia) and 7 ventilated control infants, characterizing the cells obtained by immunohistochemical analysis of lineage-specific markers and assaying macrophage-associated chemokines and cytokines in supernatant fluid. At all ages from birth, lavage supernatants demonstrated highly significant increase over controls of the beta-chemokine macrophage inflammatory protein (MIP)-1 alpha, although not of regulated upon activation, normal T cell expressed and secreted (RANTES), of the cytokines tumor necrosis factor (TNF)-alpha and IL-1 beta, and of elastase/alpha-1 antitrypsin. Significantly higher concentrations of MIP-1 alpha in particular were associated with the later development of fibrosis. Increased numbers of macrophages expressing the activation marker RM/3-1 were found at all ages in bronchopulmonary dysplasic infants, whereas neutrophil numbers were increased from d 3. Dexamethasone administered to 10 infants induced rapid decrease in inflammatory cell numbers and concentrations of MIP-1 alpha, tumor necrosis factor-alpha, IL-1 beta, and elastase/alpha-1 antitrypsin. The inflammatory response in neonatal RDS begins within the first day of life. Long-term outcome is associated with the magnitude of this early response, in particular production of MIP-1 alpha. The early introduction of specific therapy is thus likely to be beneficial.

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.

Epidermal growth factor-like molecular species in normal bronchoalveolar lavage fluid

Normal bronchoalveolar lavage fluid (BALF) contains mitogenic activity for fibroblasts and type 2 pneumocytes. A number of growth factors that might contribute to this activity have been identified in BALF. We found that a molecule or molecules able to bind to epidermal growth factor (EGF) receptors on mouse lung fibroblasts were present in normal mouse BALF and could be blocked by an antiserum to mouse EGF. Receptor binding was partially blocked by preincubation with heparin, indicating a relationship to the heparin-binding subgroup of EGF-like growth factors. Heparin markedly enhanced the mitogenic activity of BALF for fibroblasts, but we were unable to establish whether the EGF-like molecule contributed to this activity. Immunoblotting using the anti-EGF serum identified a protein of M(r) 88,000 in concentrated BALF. The cellular source and physiological role of this growth factor merit further investigation.

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.

Inhaled recombinant interferon gamma in patients with lung cancer: pharmacokinetics and effects on chemiluminescence responses of alveolar macrophages and peripheral blood neutrophils and monocytes

PURPOSE

A Phase I trial was conducted to investigate clinical toxicity, pharmacokinetics, and chemiluminescence (CL) responses of alveolar macrophages (AM) and peripheral blood neutrophils and monocytes after inhalation of recombinant interferon (r IFN)-gamma.

METHODS AND MATERIALS

Eight patients with lung cancer inhaled r IFN-gamma as single doses of 0.1, 0.2, 0.6, 1.8, or 5.4 mg. Bronchoalveolar lavage was performed three times, 21 h before as well as 3 and 27 h after inhalation.

RESULTS

Interferon-gamma was detectable in bronchoalveolar lavage fluid (BALF) samples taken 3 h after inhalation in doses of > or = 0.6 mg. Before inhalation, AM in four out of seven patients studied showed vigorous lucigenin-enhanced CL responses to N-formyl-methionyl-leucyl-phenylalanine and opsonized zymosan particles. Furthermore, the responses were markedly increased 3 h after inhalation. In three out of seven patients, AM in the pretreatment BALF samples showed low or no CL responses, and the responses did not increase after inhalation of IFN-gamma, suggesting that the patients were anergic. Postinhalation CL responses did not correlate with the dose of IFN-gamma inhaled. Circulating IFN-gamma was detected in one patient receiving the highest dose. No changes referable to IFN-gamma inhalation were found in the CL responses of blood neutrophils and monocytes. During the 24 h follow-up, two patients developed transient fever-reactions.

CONCLUSIONS

The findings suggest that inhalation may provide a way to increase alveolar concentrations of IFN-gamma and to augment respiratory burst capacity of AM without any major side effects. This approach may have clinical implications for the treatment of tumors and infections of the respiratory tract.

Analysis of cells obtained by bronchial lavage of infants with respiratory syncytial virus infection

To study the cellular infiltrate that occurs within the airways of infants with respiratory syncytial virus bronchiolitis, samples of airways secretions were obtained by bronchial lavage from the lower respiratory tract of infants ventilated for this condition and from the upper airway of non-intubated infants with this disorder using nasopharyngeal aspirates. Cytospin samples were prepared so that differential cell counts could be performed on the cells obtained and alkaline phosphatase-antialkaline phosphatase immunocytochemical analysis of lymphocyte subsets was carried out using a panel of monoclonal antibodies, which included anti-CD3, anti-CD4, anti-CD8, anti-CD19, and anti-TcR gamma delta. Results from the lower and upper airways were similar. Large numbers of inflammatory cells were obtained, of which neutrophils accounted for a median of 93% in the upper airway and 76% in the lower airway. The numbers of CD8 positive cells detected were small and consistently less than CD4 positive cells, median CD4:CD8 ratios being 22.5:1 and 15:1 for the lower and upper airways. CD19 positive cells were rarely observed and no gamma delta positive lymphocytes were detected. These results indicate that neutrophils probably play a major part in causing symptoms in these infants. They do not support the concept that excessive lymphocyte mediated cytotoxic activity is principally responsible for the pathology in respiratory syncytial virus bronchiolitis.

Concentration of amoxycillin and clavulanate in lung compartments in adults without pulmonary infection

BACKGROUND

The efficacy of an antibiotic is usually predicted from serum levels and MIC90 values for likely pathogens, but in the lung tissue concentrations may be more informative. This study compares concentrations of amoxycillin and clavulanate in serum, epithelial lining fluid (ELF), alveolar macrophages, and bronchial mucosa in 15 adults.

METHODS

Amoxycillin 500 mg and clavulanic acid 250 mg were given 1-2 hours before diagnostic bronchoscopy for haemoptysis or radiological abnormality. Mucosal biopsy samples were taken from macroscopically normal sites, alveolar macrophages harvested by lavage, and ELF volume derived from urea concentrations in bronchial lavage fluid and blood. Amoxycillin was assayed by inhibition of growth of Micrococcus lutea, and clavulanate (in serum, ELF, and bronchial mucosa) by inhibition of growth of Klebsiella pneumoniae; in macrophages clavulanate was measured by high performance liquid chromatography.

RESULTS

The median concentrations in serum were 6.90 mg/l for amoxycillin and 5.25 mg/l for clavulanate. The median bronchial mucosal concentration of amoxycillin was 2.99 mg/l and of clavulanate was 1.65 mg/l; the median concentrations in ELF were 0.89 and 0.96 mg/l, and in macrophages 0 and 0.76 mg/l, respectively. In macrophages amoxycillin levels were undetectable in 10 of 14 subjects (71%); by contrast, only 6 of 14 subjects (43%) had no detectable clavulanate.

CONCLUSIONS

Clavulanate levels exceeded quoted MIC90 values (around 0.25 mg/l) for Legionella pneumophila both in ELF and in macrophages. Amoxycillin-clavulanate may therefore have a clinical role in infections with Legionella pneumophila.

Tropical respiratory medicine. 4. Acute tropical infections and the lung

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Bronchoalveolar lavage

Bronchoalveolar lavage has a well established role in the diagnosis of pulmonary infections, particularly those due to opportunistic organisms in an immunocompromised host. Recent studies of infants and adults with inflammatory lung disease have helped our understanding of the mechanisms underlying these disorders and their responses to treatment. With increasing recognition that pulmonary events in utero and in early infancy are important in the pathogenesis of lung diseases such as asthma, studies of the lung's responses to various environmental insults in this population might guide us to developing effective preventative and therapeutic strategies. Bronchoalveolar lavage is one method for assessing a number of pulmonary components and may be useful in this regard, particularly if combined with new methods for examining inflammatory responses, such as those utilising the polymerase chain reaction to assess cellular expression for inflammatory cytokines and growth factors.

Effect of nitrogen dioxide on synthesis of inflammatory cytokines expressed by human bronchial epithelial cells in vitro

Although studies of nitrogen dioxide (NO2) inhalation, in both animals and humans, have demonstrated that this agent can cause epithelial cell damage and inflammation of the airway epithelium, the mechanisms underlying these effects are not well understood. We have cultured human bronchial epithelial cells, as explant cultures from surgical tissue, and studied these firstly from their ability to constitutively synthesize specific proinflammatory cytokines and then investigated the effect of exposure to NO2 on the generation of these cytokines. Constitutive synthesis of cytokines was evaluated by analysis of both the expression of the mRNA for interleukin (IL)-1 beta, IL-4, IL-8, granulocyte/macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma), by the polymerase chain reaction (PCR), and by immunocytochemical staining for the presence of cell-associated IL-1 beta, IL-8, GM-CSF, TNF-alpha, and IFN-gamma, using specific monoclonal and polyclonal antibodies directed towards these cytokines. Release of IL-4, IL-8, GM-CSF, TNF-alpha, and IFN-gamma following exposure to 5% CO2 in air or 400 ppb and 800 ppb NO2 for 6 h was investigated by enzyme-linked immunosorbent assay. PCR demonstrated that the human bronchial epithelial cells expressed the mRNA for IL-1 beta, IL-8, GM-CSF, and TNF-alpha but not for IL-4 and IFN-gamma. Immunocytochemical staining confirmed the presence of endogenous IL-1 beta, IL-8, GM-CSF, and TNF-alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Inflammatory cells in the lungs of premature infants on the first day of life: perinatal risk factors and origin of cells

Neither the origin of leucocytes in the premature newborn airway nor their relationship to perinatal factors has been adequately determined. In order to sample airway cells, modified bronchoalveolar lavage was performed on 74 intubated infants of < 32 weeks' gestation and < 24 hours of age. Cells were counted, stained and, in a small separate group of six infants, four boys and two girls, probed for the Y chromosome with suitable control samples. Perinatal risk factors for increased airway cellularity were analysed by multiple regression. Premature rupture of membranes of more than 24 hours' duration was independently associated with increased numbers of airway leucocytes (n = 74). More than 90% of airway leucocytes from four boys with pulmonary inflammation were positive for the Y chromosome indicating that the cells were of fetal rather than maternal origin.

Four markers of collagen metabolism as possible indicators of disease in the adult respiratory distress syndrome

During the adult respiratory distress syndrome (ARDS), an irreversible fibrotic process can occur extremely rapidly. To establish indices of ARDS in pneumonia as well as the severity of the lung fibrosis, we have undertaken for the first time a study of four markers of collagen metabolism obtained from both bronchoalveolar lavage fluid (BALF) and serum: Type I (CI), Type III (CIII), N-terminal peptide of Type III procollagen (PIIINP), and galactosylhydroxylysylglucosyltransferase activity (GGT). We studied 61 patients (13 coma controls, 29 with pneumonia, and 19 with ARDS). In BALF, the average values of CI, CIII, PIIINP, and GGT were significantly higher in ARDS than in the control patients. The values for patients with pneumonia, although increased, were significantly lower than those in ARDS for CI, CIII, and PIIINP. In serum, the mean CI and PIIINP were significantly increased in pneumonia and ARDS, but the mean CIII was significantly increased only in ARDS compared with the control group. Significant positive linear correlations were observed for ARDS between CI and CIII or PIIINP and CIII in BALF and serum. Such correlations were observed for pneumonia only in serum. Molecular mass determinations demonstrated that CI- and CIII-related antigens in BALF were essentially intact triple helices of collagens or procollagens. Among patients with histologically defined interstitial fibrosis, the level of PIIINP in BALF was significantly higher for those with an additional intraalveolar fibrosis. In conclusion, measurements of these collagen markers may be useful for assessing disease activity and reflecting the flux of collagen molecules in the lung.

Evaluation of albumin as a reference marker of dilution in bronchoalveolar lavage fluid from asthmatic and control subjects

BACKGROUND

Standardised expression of results of bronchoalveolar lavage (BAL) is problematical in the absence of a validated "denominator" of epithelial lining fluid dilution. The suitability of albumin in BAL fluid has been investigated in groups of clinically stable asthmatic and control subjects.

METHODS

Absolute levels of albumin in BAL fluid were measured in a preliminary study of 21 asthmatic and 10 control subjects. In a more complex study designed to investigate the origin of albumin sampled at BAL in nine asthmatic and seven control subjects, radiolabelled albumin was injected intravenously five minutes before BAL.

RESULTS

In the preliminary study levels of albumin in BAL fluid were very similar, with a geometric mean value of 44 (95% CI 35-54) micrograms/ml BAL supernatant for the asthmatic subjects and 41 (95% CI 33-52) micrograms/ml for the controls. The majority of control and asthmatic subjects in the radiolabel study exhibited minimal flux of albumin from the circulation into the BAL aspirate. This finding was not uniform, however, and in a third of the asthmatic subjects an albumin flux equivalent to > 20% of the measurable albumin was found in two or more aliquots of a 3 x 60 ml lavage.

CONCLUSIONS

The results of this investigation into the source of albumin sampled at BAL suggest that, in general, albumin would be a reasonable reference solute for normalising the degree of dilution of BAL fluid in the groups studied. The origin of albumin was not always restricted to the bronchopulmonary segment under investigation, however, with significant leakage from the blood compartment in some individuals despite the consistency of absolute levels observed in the preliminary study.

Primary Sjögren's syndrome

Significant abnormalities in pulmonary function are encountered in about 24% of patients with primary Sjögren's syndrome. The most common cause of dyspnoea is interstitial fibrosis, with a prevalence of around 8%, but a number of other pathologies may be encountered in the lungs of these patients (Table 1). Lymphoproliferative disorders are relatively uncommon, but these apparently benign lesions may harbour malignant potential. Interstitial fibrosis and the lymphoproliferative disorders may be responsive to corticosteroids or cytotoxic agents, and it is therefore important to establish an accurate diagnosis at an early stage. On the basis of our experience we would recommend the investigative strategy outlined below. Patients should be screened for significant lung disease by taking a careful history of respiratory symptoms followed by standard pulmonary function testing (including measurement of carbon monoxide diffusing capacity) and chest radiography. High resolution computed tomography is a non-invasive technique that should prove superior to chest radiography in the detection of early cases of interstitial fibrosis. When the disease is patchy it may be useful in identifying areas of maximal involvement for subsequent biopsy. Bronchoalveolar lavage is a sensitive tool in the non-smoker, but lacks the specificity to command a significant role in the investigation of pulmonary pathology in these patients. One exception to this may be in the investigation of the clonality of lymphocytes which may allow early and specific diagnosis of lymphomatous proliferation. The application of techniques such as the polymerase chain reaction may assist in the investigation of the role of the Epstein-Barr virus in the causation of lymphoproliferative lesions. In most patients with significant symptoms and abnormalities of pulmonary function a tissue diagnosis will be required, either by transbronchial biopsy or by open lung biopsy. Both bronchial and interstitial lung tissue should be obtained where possible. Histological confirmation is probably mandatory when there is a recent history of parotid enlargement, weight loss or the appearance of a monoclonal gammopathy. Advances in our understanding of the mechanisms of the MALT system may provide the key to unlocking some of the mysteries of 'autoimmune' diseases such as Sjögren's syndrome. The response of lymphoproliferative disorders to immunosuppressive therapy provides hope that if the diagnosis of sicca syndrome can be made earlier lymphocyte induced tissue damage may be halted or reversed.

Clinical usefulness and safety of bronchoalveolar lavage (BAL) in elderly patients

Little is known about the indications, safety and clinical usefulness of bronchoalveolar lavage (BAL) in elderly patients. In order to address these issues, we reviewed our last 200 consecutive BAL procedures, of which 23 (11.5%) were performed in patients older than 75 years (range 75-90, mean age 80.7 years, 13 men and 10 women). All procedures were well tolerated and no complications were observed. In 17 of the 23 patients (74%), BAL results were compatible with or diagnostic for infectious pneumonia (6 cases), idiopathic pulmonary fibrosis (5 cases), lung cancer (2 cases), hypereosinophilic syndrome (2 cases), chronic eosinophilic pneumonia (1 case) and lymphoma (1 case). In 6 of the 23 patients (26%), BAL yielded no specific diagnostic information. These data indicate that BAL is a safe procedure with a high diagnostic yield in an elderly population with pulmonary disease of unknown origin.

The use of the nose to study the inflammatory response of the respiratory tract

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Detection of mycobacterial DNA in sarcoidosis and tuberculosis with polymerase chain reaction

The cause of sarcoidosis is unknown. However, the histological similarity between the disorder and tuberculosis suggests that mycobacteria might contribute to the pathogenesis of sarcoidosis. We have used the polymerase chain reaction (PCR) to detect mycobacterial DNA in clinical samples from patients with sarcoidosis. 104 patients were included in the study (62 referred for possible tuberculosis and 20 for possible sarcoidosis, and 22 control patients who had undergone bronchoscopy for other reasons). Bronchoalveolar lavage samples, bronchial washings, and tissue specimens (1 from each patient) underwent assay by PCR as well as bacteriological, histological, and cytological examination. We used two PCR reactions: in the first the complex-specific insertion sequence IS986/IS6110 was used to specifically detect DNA from Mycobacterium tuberculosis complex bacteria; in the second, conserved sequences of the mycobacterial groEL gene were used to detect DNA from mycobacteria other than M tuberculosis. The PCR was more sensitive than culture for diagnosis of tuberculosis. However, the false-positive PCR rate for M tuberculosis was 9%. M tuberculosis DNA was found in half the sarcoidosis patients, and non-tuberculosis mycobacterial DNA in a further 20%. The findings that a significant proportion of the sarcoidosis patients in this study have mycobacteria in their lungs and that most of these mycobacteria belong to M tuberculosis complex suggest an aetiological role for mycobacteria in sarcoidosis.