F. E. Hargreave

Measurement of inflammatory indices in induced sputum: effects of selection of sputum to minimize salivary contamination

Sputum examination is being used increasingly as a noninvasive method to assess airway inflammation. Expectorated sputum has variable contamination with saliva. Methods of processing have included the selection of portions of the sample considered to be representative of pulmonary origin versus use of the whole specimen, which is confounded by varying volumes of saliva. We compared cell profiles and eosinophilic cationic protein (ECP) concentration in sputum selected from the expectorate and in the usually discarded residual portion to determine to what degree salivary contamination is minimized and if the results are representative of lower respiratory secretions. Sputum was induced with hypertonic saline in six healthy and nine asthmatic subjects. All portions considered to be of pure lower respiratory tract origin were selected from the residual. The selected and residual portions were treated with dithiothreitol, total cell counts and cell viability were obtained, cytospins were made for differential cell counts and supernatant was collected for ECP assay. Selected portions of the specimens, in comparison with the residual portion showed: little squamous cell contamination (median 1.2 vs 70%; p < 0.001); higher total cell counts.mL-1 (5.1 vs 0.5 x 10(6) cells.mL-1; p < 0.001); higher number of viable nonsquamous cells per sample (1.9 vs 0.6 x 10(6) cells; p < 0.001); higher slide quality score (7 vs 4; p < 0.001); and higher levels of ECP (768 vs 136 micrograms.L-1; p < 0.001). There were no differences in the differential cell counts of eosinophils (1.3 vs 3.8%), neutrophils (44 vs 32%), and lymphocytes (0.6 vs 0.6%). While the proportion of macrophages was lower (36 vs 54%; p < 0.05), the absolute number (41 vs 19 x 10(4) cells; p < 0.05) was higher in the selected portion. In summary, selection of all portions of induced sputum from the expectorate minimized the confounding influence of saliva. Loss of nonsquamous cells in the residual portion was variable but usually less than one third of those in the selected portion. With one exception, this loss had little influence on the differential counts of inflammatory cells. Similar observations apply to eosinophilic cationic protein levels. We conclude that, in healthy subjects and treated asthmatics, inflammatory markers in the selected portion of the expectorate can be used to represent those in the lower respiratory tract in general.

Standardised methodology of sputum induction and processing

Research into the pathogenetic mechanisms and clinical monitoring of inammatory diseases of any system is complete only if it involves the study of both the underlying pathological features and the physio- logical consequences that result from what are always complex inammatory processes. Respiratory dis- eases, including those of the airways, are no exception in this respect. It is, therefore, not surprising that the development over the last 25 years of techniques enabling the study of inammatory processes in the airways has revolutionised understanding of the commonest pulmonary diseases, asthma and chronic obstructive pulmonary disease (COPD). Airways inammation is now an established feature and a central consideration of any treatment strategy for both of these conditions. Most of the initial observations made in asthma, documenting the involvement of eosinophils, mast cells, T-cells and more recently structural cells, ® broblasts, endothelial cells and epithelial cells, were made in studies using ® breoptic bronchoscopy in

Stable COPD: predicting benefit from high-dose inhaled corticosteroid treatment.

The role of inhaled corticosteroids in the management of chronic obstructive pulmonary disease (COPD) remains controversial. The purpose of this study was to evaluate whether sputum eosinophilia (defined as eosinophils ≥3%) predicts clinical benefit from inhaled corticosteroid treatment in patients with smoking-related clinically stable moderate-to-severe COPD. Forty consecutive patients with effort dyspnoea (mean age 67 yrs; 52 pack-yr smoking history; post-bronchodilator forced expiratory volume in one second (FEV1) <60% predicted, consistent with moderate-to-severe smoking-related chronic airflow limitation) were enrolled. Subjects were treated with inhaled placebo followed by inhaled budesonide (Pulmicort Turbuhaler® 1,600 µg·day−1), each given for 4 weeks. While the treatment was single-blind (subject level), sputum cell counts before and after treatment interventions were double-blind, thus removing bias. Outcome variables included spirometry, quality-of-life assessment and 6-min walk test. Sputum eosinophilia was present in 38% of subjects. In these, budesonide treatment normalised the eosinophil counts and, in comparison to placebo treatment, resulted in clinically significant improvement in the dyspnoea domain of the disease-specific chronic respiratory questionnaire (0.8 versus 0.3) and a small but statistically significant improvement in post-bronchodilator spirometry (FEV1 100 mL versus 0 mL; p<0.05). In conclusion, sputum eosinophilia predicts short-term clinical benefit from high-dose inhaled corticosteroid treatment in patients with stable moderate-to-severe chronic obstructive pulmonary disease.

Exacerbations of asthma without sputum eosinophilia.

BACKGROUND--Sputum analysis provides a non-invasive method of examining the airway secretions of subjects with asthma in order to better understand the inflammatory process. Increased proportions of eosinophils are generally seen in the sputum of subjects with asthma, especially when there is an exacerbation. An unexpected observation in the sputum of subjects with mild exacerbations of asthma is reported. METHODS--Thirty four consecutive subjects with symptoms consistent with a mild exacerbation of asthma were recruited for a treatment study. Inclusion criteria required persistent symptoms of chest tightness, dyspnoea, or wheezing for two weeks (without spontaneous improvement or alteration in dose of inhaled corticosteroid) and a forced expiratory volume in one second (FEV1) that was reversible to more than 75% predicted or known best to ensure the exacerbation was mild. Sputum (spontaneous or induced with hypertonic saline) from all subjects was examined for differential cell counts. Eosinophilic sputum was defined as > or = 4% eosinophils on two occasions or > 10% eosinophils once. Clinical characteristics, sputum differential counts, and measurements of airways obstruction were compared between the subjects with and without sputum eosinophilia. RESULTS--Almost half of the subjects (16 of 34) considered to have mildly uncontrolled asthma had no sputum eosinophilia. In comparison with the subjects who had sputum eosinophilia the non-eosinophilic group had less airways obstruction (FEV1% predicted 88% v 70%) and less severe airways hyperresponsiveness (PC20 methacholine 0.45 mg/ml v 0.13 mg/ml). There was no difference between the groups in the type or prevalence of symptoms, history of recent infections, smoking, relevant allergen exposure, or use of inhaled corticosteroid. CONCLUSIONS--Symptoms of mildly uncontrolled asthma are not always associated with eosinophilic airways inflammation as measured by sputum analysis. The causes and treatment of the non-eosinophilic condition require further investigation.

Induced sputum, bronchoalveolar lavage and blood from mild asthmatics: inflammatory cells, lymphocyte subsets and soluble markers compared

Airway inflammation in asthma can be measured directly by invasive bronchoalveolar lavage (BAL), directly and relatively noninvasively by induced sputum and indirectly from peripheral blood. We compared cellular and fluid phase indices of inflammation in induced sputum, BAL and blood from 11 adults with mild stable asthma. On one day, induced sputum selected from saliva was collected and on the next, blood and BAL. Median results of sputum compared with BAL showed a higher number of nonsquamous cells (53 versus 0.8 x 10(6) cells x mL(-1), p=0.003), more neutrophils (34.3 versus 1.0%, p<0.001), CD4+ and CD19+ T-cells (76.5 versus 54.7%, p=0.01 and 5.2 versus 1.1%, p=0.03, respectively), fewer macrophages (603 versus 95.0%, p=0.002) and markedly higher levels of eosinophil cationic protein (ECP) (264 versus 2.0 microg x L(-1), p<0.001), tryptase (17.6 versus 2.2 UI x L(-1), p<0.001) and fibrinogen (1,400 versus 150 microg x L(-1), p=0.001). Sputum and BAL neutrophils and CD4+ T-cells were strongly correlated. Sputum and BAL differed from blood by having higher proportions of T-cells (94.9 and 98.9% versus 87.7%, p=0.002) and lower proportions of CD19+ T-lymphocytes (p=0.04 and 0.006). Sputum also differed from blood by having higher proportions of CD4+ T-cells (76.5 versus 51.4%, p=0.001), lower proportions of CD8+ cells (24.0 versus 403%, p=0.04) and a higher CD4+/CD8+ ratio (3.3 versus 1.4, p=0.01). We conclude that in mild asthmatics, sputum, bronchoalveolar lavage and blood measure different compartments of inflammation. Induced selected sputum has the advantage over bronchoalveolar lavage of higher density of cell recovery and stronger signal for fluid-phase markers.

Induced sputum cell and fluid-phase indices of inflammation: comparison of treatment with dithiothreitol vs phosphate-buffered saline

Treatment of sputum with dithiothreitol (DTT) gives reliable measurements of cellular and fluid-phase markers of airway inflammation. We investigated the extent to which DTT treatment influences these measurements as compared with phosphate-buffered saline (PBS). Hypertonic saline-induced sputum, collected from 20 asthmatic subjects, was examined within 2 h. All portions which looked more solid (less fluid) than saliva were collected from the expectorate. The selected sputum was then divided into two portions: one treated with one volume of DTT and one volume of PBS, the other with two volumes of PBS. The filtrates were assessed blind for total and differential cell count, viability, and fluid-phase eosinophil cationic protein (ECP), fibrinogen, interleukin (IL)-5 and IL-8. Sputum treated with DTT compared with PBS had lower proportions of viable cells (median 66 versus 74%; p=0.003). In contrast, DTT-treated sputum had higher total cell counts (median 8.8 vs 2.8 x 10(6) mL(-1); p<0.001) and levels of ECP (median 1340 vs 584 mg x L(-1); p<0.001) The measurements were similar with respect to the proportion of eosinophils, neutrophils, lymphocytes, macrophages, and fluid-phase fibrinogen, IL-5 and IL-8. We conclude that dithiothreitol disperses cells more effectively and that this might account for the higher levels of eosinophil cationic protein. Dithiothreitol may affect cell viability, but the changes are not relevant with respect to cell counts. Additionally, dithiothreitol does not seem to influence the other measurements performed.

Success and safety of sputum induction in the clinical setting

It has previously been reported that sputum induction is successful and safe in the clinical research setting. The authors examined the success and safety of sputum induction in routine clinical practice in patients with asthma or chronic airflow limitation of varying severity. Records of 304 patients with asthma and 25 with smoking related chronic airflow limitation were examined retrospectively. All had sputum induced as part of their routine clinical evaluation. When the baseline post salbutamol forced expiratory volume in one second (FEV1) was > or =70% predicted, the inductions consisted of inhalation of an aerosol of 3%, 4% and 5% saline, each given for 7 min. If the FEV1 was <70%, or there were other reasons for concern, the inductions were initiated with normal saline for shorter periods. Inhalations were discontinued when sputum was obtained or when there was a fall in FEV1 > or =20%. Success was identified by obtaining nonsquamous total and differential cell counts containing macrophages, and safety by the fall in FEV1. The overall success was 93%. The procedure was safe even amongst patients with an FEV1 of <60% and <1 L. Of 77 patients with an FEV1 between 40-59%, 8% fell by > or =20% and of 35 patients with an FEV1 <40%, 6% fell by 20%. Carefully standardized sputum induction can be successful and safe in patients with asthma or chronic airflow limitation in clinical practice, even when moderate or severe airflow limitation is present.

Occupational eosinophilic bronchitis without asthma: An unknown occupational airway disease

The introduction of reliable methods to measure inflammatory Cells in sputum has made it possible to identify the occurrence of eosinophilic bronchitis without asthma? Patients are first seen with a chronic cough without variable airflow limitation or airway hyperresponsiveness, and the condition Js reversed by glucocorticoid treatment. 2 For the first time, we descrlbe a case of eosinophilic bronchitis related to exposure to acrylates in the workplace. CASE REPORT A 50-year-old woman was employed for 2 years at a company that produced weather strips for vehicles. The job required her to use glue containing cyanoacrylate and methacrylate, which are known to induce occupational asthma. Three months after starting this work she noticed shortness of breath, chest tighthess, wheezing, and persistent dry cough, as well as nasal symptoms such as a runny, stuffy nose and sneezing when at work. These symptoms improved substantially on weekends. She was a 15 pack-year smoker and quit 20 years ago. Her family history was negative for allergies and asthma. Results of physical examination and chest radiography were normal. Allergy skin prick test responses to 19 common extracts were negative. Her treatment had consisted of albuterol inhaler as needed and budesonide nasal spray (200 ixg/day) for 1.5 months and Tegretol (200 mg/day) for petit mal epilepsy.

Steroid naive eosinophilic asthma: anti-inflammatory effects of fluticasone and montelukast

Background: Inhaled corticosteroids and leukotriene receptor antagonists reduce airway eosinophilia and have been used as first line anti-inflammatory therapy for mild persistent asthma. Methods: A multicentre, randomised, placebo controlled, parallel group study was performed to compare the anti-inflammatory effects of fluticasone propionate and montelukast as measured by sputum eosinophils in 50 adults with symptomatic steroid naive asthma and sputum eosinophilia of ⩾3.5%. Results: Eighteen patients received low dose fluticasone (250 μg/day), 19 received montelukast (10 mg/day), and 13 were given placebo for 8 weeks. Fluticasone treatment resulted in a greater reduction in sputum eosinophils (geometric mean (SD) 11.9 (2.3)% to 1.7 (5.1)%) than montelukast (10.7 (2.3)% to 6.9 (3.8)%; p = 0.04) or placebo (15.4 (2.4)% to 7.8 (4.2)%; p = 0.002), and improvement in FEV1 (mean (SD) 2.6 (0.9) l to 3.0 (0.9) l) than montelukast (2.8 (0.7) l to 2.8 (0.9) l; p = 0.02) or placebo (2.4 (0.8) l to 2.4 (0.9) l; p = 0.01). Treatment with fluticasone suppressed sputum eosinophilia within a week while montelukast only attenuated it. The effect of montelukast was maximal at 1 week and was maintained over 4 weeks. The effect of fluticasone was maintained over 8 weeks while that of montelukast was not. Conclusions: Montelukast is not as effective as low dose fluticasone in reducing or maintaining an anti-inflammatory effect in steroid naïve eosinophilic asthma.

Induced sputum: time from expectoration to processing

One of the limitations in the use of induced sputum to measure indices of airway inflammation is the perceived need to process the sample within 2 h. Therefore, the authors investigated whether the processing of induced sputum could be delayed. Induced sputum samples obtained from asthmatic subjects (n=30) were examined. Each sample was stored at 4°C. A portion was selected and processed within 2 h and the remaining expectorate (sputum plus saliva) was refrigerated. Later an equal amount was selected and processed at either 9 (n=15) or 18 (n=15) h. The sputum was examined for cell counts and viability, fluid-phase eosinophil cationic protein (ECP), interleukin‐8 (IL‐8) and fibrinogen. Repeatability of measurements was assessed by the interclass correlation coefficient (ICC). Measurements obtained at 9 h did not differ from those made at 2 h and the repeatability was excellent (ICC 0.88–0.99). However, by 18 h the median cell viability was reduced from 65.0% to 43.0% and the ICC was generally lower: 0.10 for total cell count, 0.24 for viability, 0.60 for neutrophils, 0.90 for eosinophils, 0.56 for macrophages, 0.76 for ECP, 0.82 for IL‐8 and 0.84 for fibrinogen. The results indicate that when induced sputum from subjects with asthma is kept at 4°C, examination of cell counts can be delayed for ⩽9 h and for the fluid-phase indices measured for ⩽18 h. Further investigation of this issue is required for spontaneous sputum, other airway diseases and other inflammatory markers.