Sputum eosinophilia in chronic bronchitis and asthma

Chronic obstructive pulmonary disease . 6: The aetiology of exacerbations of chronic obstructive pulmonary disease

Exacerbations of COPD are thought to be caused by interactions between host factors, bacteria, viruses, and changes in air quality to produce increased inflammation in the lower airway. The evidence for this and the potential mechanisms by which they result in the characteristic symptoms of exacerbations is reviewed. A better understanding of the causes and processes is needed for the appropriate use of existing treatments and the development of new ones. Future studies need to define populations clearly, stratify for known confounding factors, and should aim to identify clinical correlates so that clinical practice can be modified appropriately.

Eosinophilic airway inflammation as an underlying mechanism of undiagnosed prolonged cough in primary healthcare patients

Prolonged cough is a common problem in patients seen in general practice. Using a simple method of sputum induction and processing of sputum samples, we determined whether eosinophilic airway inflammation could be a cause of undiagnosed prolonged cough. Eighty-two patients who had had cough for more than 1 month were enrolled into the study, in six primary healthcare centres. Patients with known pulmonary disease, including asthma or chronic obstructive pulmonary disease (COPD), or who were known to have another cause of cough, or to have recently suffered from a respiratory infection, were excluded. Fifty-three healthy individuals served as controls. Sputum was induced by inhalation of 3% saline. Inflammatory cells in smears were studied semi-quantitatively. Concentrations of eosinophil cationic protein (ECP), eosinophil peroxidase (EPO), myeloperoxidase (MPO) and human neutrophilic lipocalin (HNL) were determined. Sputum induction proved safe and adequate samples were obtained from 91%. Sputum eosinophilia (eosinophils accounting for more than 5% of all cells in smears) was present in 14 patients with prolonged cough (19%) but in no healthy individual (P=0.001). Five of the 14 individuals (36%) who exhibited sputum eosinophilia appeared to have asthma, while nine of the 14 (64%) did not. Concentrations of ECP and EPO were higher in patients with prolonged cough than in healthy individuals (P=0.02 for ECP; 0.005 for EPO). We conclude that eosinophilic airway inflammation is a fairly common cause of prolonged cough, even in patients not suffering from asthma or COPD, or in whom no other cause of cough is known to be present. Induced sputum samples obtained in health centres can be studied in a central laboratory. Detection of eosinophilic airway inflammation could aid the decision regarding treatment.

Sputum cytopathological findings in pig farmers

The purpose of this study is to compare the cytological changes in the respiratory tracts of pig farmers exposed to an environment of swine confinement buildings with control, non-exposed subjects living in the same geographical area. Spontaneously produced sputum specimens were obtained from 133 pig farmers and 120 control subjects, all clinically healthy, and grouped according to smoking habits and sex. The findings of siderophages, eosinophils, abnormal columnar cells and respiratory spirals were significantly more frequent in the pig farmers. Siderophages were noted in 25.6% of pig farmers and in 5% of control subjects. By logistic regression analysis, pig farming is the single predictive factor for siderophages and eosinophils. For other cytological abnormalities, except Creola bodies and granular debris, smoking is the most significant predictive variable, but pig farming, age and male sex also correlate with smoking. Atypical squamous metaplasia was observed in 11.3% of pig farmers and in 5.8% of control subjects. These findings are in concordance with previous epidemiological and clinical studies and also reveal a new aspect of the harmful effect of pig farming exposure to the vascular and epithelial structures of the respiratory tract. It also demonstrates the usefulness of the simple method of sputum cytological analysis.

Prediction of respiratory symptoms by peripheral blood neutrophils and eosinophils in the First National Nutrition Examination Survey (NHANES I)

To examine specific cellular markers of inflammation in peripheral blood (neutrophils and eosinophils) and their relationship to respiratory symptoms, we used data from the First National Health and Nutrition Examination Survey (NHANES I). Cross-sectional data were available on a random sample of 6,913 adults aged 30 to 74 years who had American Thoracic Society-National Heart, Lung, and Blood Institute questionnaire information on respiratory symptoms and illnesses, including asthma, chronic bronchitis, dyspnea (grade 3), chronic cough, and chronic phlegm. Information was available on age, race, smoking status, peripheral blood leukocyte count, and differential cell count. These data were analyzed using logistic regression controlling for age, race, sex, and cigarette smoking. Physician-diagnosed asthma was significantly associated only with the eosinophil count (p = 0.001). Physician-diagnosed bronchitis was significantly associated with the neutrophil count (p = 0.012) and marginally associated with the eosinophil count (p = 0.072). Chronic phlegm was also significantly associated with both the eosinophil count (p = 0.049) and the neutrophil count (p = 0.041). Grade 3 dyspnea (p = 0.049) was only significantly associated with the neutrophil count. These data suggest that both peripheral blood neutrophils and eosinophils are associated with a broad range of respiratory symptoms and that the eosinophil may play a role in nonasthmatic respiratory inflammation.

Cellular and biochemical analysis of induced sputum from asthmatic and from healthy subjects

To determine the feasibility of cellular and biochemical analysis of sputum induced after inhalation of hypertonic (3%) saline, we analyzed sputum induced in 10 healthy and in 18 asthmatic subjects. We also analyzed saliva samples from all subjects. The entire sputum sample and the saliva sample were reduced using dithiothreitol, and cell counts and differentials were determined. Biochemical analysis was performed on sputum and saliva supernatants obtained after centrifugation. We found that induced sputum from asthmatic subjects had a higher percentage of eosinophils [8.1 +/- 3.43 (mean +/- SEM) versus 0.03 +/- 0.02%, p < 0.009] (after excluding squamous cells) and also had higher levels of albumin (232.3 +/- 54.8 versus 79.5 +/- 9.7 micrograms/ml, p < 0.02), fibrinogen (44.2 +/- 11.6 versus 11.9 +/- 2.5 micrograms/ml, p < 0.008) and eosinophil cationic protein (ECP) (142.6 +/- 34.2 versus 26.1 +/- 4.7 ng/ml, p < 0.006) but not of histamine or tryptase. In saliva, squamous cells made up more than 99% of the cells in both groups, and protein concentrations were not significantly different. We conclude that cellular and biochemical analysis of induced sputum is feasible in healthy and in asthmatic subjects and that it reveals differences similar to those reported from analyses of bronchial lavage fluid.

Inflammation and airway reactivity in asthma

The increased airway reactivity characteristic of asthma may be due to contraction of airway smooth muscle, mucus hypersecretion, edema and thickening of airway walls, and the presence of serum proteins and inflammatory cells and their products in the airways. Increased airway reactivity in asthma correlates with airway epithelial damage and is clearly related to airway inflammation, a process that most likely involves a complex interaction among mast cells, lymphocytes, eosinophils, and macrophages. Thus, although symptomatic treatment of airway narrowing is best accomplished with bronchial smooth muscle relaxants, treatment of the basic pathophysiologic defect should attempt to reduce airway inflammation. Bronchodilators (inhaled beta-agonists and, occasionally, theophylline), which do not decrease airway reactivity, are often used to treat the symptoms of patients with mild or episodic asthma; inhaled corticosteroids, which do decrease airway inflammation and reactivity, are used to treat patients with more severe symptoms. Methotrexate and cromolyn sodium may also be used, although their role in treating the underlying pathophysiology remains controversial. Identification of new agents that are as effective as corticosteroids but that do not produce their side effects would represent a major therapeutic advance for patients with asthma.

Asthma, hay fever, and phlegm production associated with distinct patterns of allergy skin test reactivity, eosinophilia, and serum IgE levels. The Normative Aging Study

We investigated the relationship of three phenotypic markers of atopy (allergy skin test reactivity, serum IgE level, and eosinophilia) to the prevalence of respiratory symptoms in 1,071 middle-aged and older men participating in the Normative Aging Study. Participants had all been health screened at the onset of the study in the 1960s to exclude individuals with asthma or other chronic respiratory diseases. Respiratory symptoms were grouped into three categories: asthma (adult onset) and other wheezing syndromes; cough and phlegm production; and hay fever. Multivariate logistic regression models were utilized to assess the independent relationship of each phenotypic marker to symptom prevalence adjusted for age, cigarette smoking, and the competing influence of the other markers. In this population, the prevalence of each symptom increased with serum total IgE concentration, this relationship being strongest for asthma. Skin test positivity (greater than or equal to 5 mm induration to one or more aeroallergens) was strongly associated with hay fever but was not significantly associated with symptoms of wheeze or cough and phlegm. Eosinophilia was associated with asthma and with phlegm production. The association of eosinophilia with phlegm production was present in skin test-negative as well as skin test-positive subjects and remained significant even after current smokers and individuals with asthma or hay fever were excluded. These data support the concept that asthma and hay fever are related to different immunologic host factors as reflected by expression of atopy phenotypes. Future investigations of immunologic factors in respiratory disease susceptibility should include, at a minimum, an assessment of all three phenotypic markers of atopy.

Sputum cell counts in airway disease: a useful sampling technique

Quantitative sputum cell counts from patients with asthma and chronic bronchitis were performed and found to be reproducible. Sputum from carefully characterized subjects with asthma contained large numbers of eosinophils and formalin-sensitive metachromatic (mast) cells. In contrast, the macrophage was the dominant cell type in the sputum from smokers with chronic bronchitis. In a third group of patients with corticosteroid responsive-chronic cough and normal methacholine airway responsiveness the sputum contained eosinophils and metachromatic cells, similar to the asthmatic subjects. Sputum cell counts are a useful, noninvasive method for the identification of this pattern of inflammatory response in patients with airway diseases.

Cellular characteristics of sputum from patients with asthma and chronic bronchitis

The reproducibility of sputum cell counts was examined and the cell counts in patients with asthma were compared with those in patients with chronic bronchitis. Three groups of subjects were studied. Sputum from eight patients with chronic asthma and with sputum production were studied to determine the reproducibility of sputum cell counts. The findings in 10 non-smokers with asthma uncomplicated by other airway disease examined at the time of an exacerbation with sputum (group 2) were compared with those from eight smokers with chronic cough and sputum but no features of asthma (group 3). Sputum plugs were selected by microscopy to ensure their origin from the lower respiratory tract. A total cell count was performed on a trypsinised suspension, and differential and metachromatic cell counts were performed on undiluted plugs. The within specimen and test-retest reproducibility of these measurements was high (reliability coefficient, R, = 0.99 and 0.89). The sputum of the asthmatic patients was characterised by eosinophilia (69%, range 46-92%) and the presence of formaldehyde blockable metachromatic cells (1.5%, range 0.6-2.8%). In comparison, the sputum of the patients with chronic bronchitis had few eosinophils (0.5%) or metachromatic cells (0.14%); the dominant cell type was the macrophage (83%). It is concluded that sputum cell counts are reproducible in the short term, the inflammation of asthma is characterised by eosinophilia and metachromatic cells in sputum, and sputum may provide a useful source of cells for investigating the cellular characteristics of airway inflammation.

Factors affecting the decline of ventilatory function in chronic bronchitis

Ninety six middle aged male patients with chronic bronchitis with relatively well preserved ventilatory function who were resident in Queensland, New South Wales, or Victoria took part in a prospective study to determine the relationship of various factors to the rate of decline of the FEV1. Thirty of the subjects withdrew, leaving 66 to be followed for four to six years. The mean rate of decline of the FEV1 was 58.6 (SD 51.4) ml/year. The subjects' ventilatory responses to bronchodilator and to methacholine (measures of bronchial lability) were significantly related to each other and to sputum eosinophilia. With a linear model for the data on 57 patients who had methacholine and skin tests the rate of decline of the FEV1 was found, after adjustment had been made for other variables, to be significantly related to State of residence, current smoking, response to bronchodilator, age, and occupational exposure to dust. Response to bronchodilator was interchangeable with response to methacholine. With the five variables in the model none of the following factors was related to the rate of decline of the FEV1:FEV1 on entry, FEV1% predicted normal, FEV1/VC%, skin test reaction, occupation on entry, history of sinusitis and rhinitis, and height. When data from all 66 subjects were introduced into the model, in addition to the five significant individual variables (FEV1/VC% X response to bronchodilator) was significantly related to the rate of decline of the FEV1. Of these prognostic indices, response to bronchodilator was independent of the initial FEV1, FEV/VC%, and FEV1% predicted. The difference between States, which was not explained by differences due to sampling or withdrawal of subjects, was due to a low rate of decline in Queensland.

Sputum and blood eosinophils during corticosteroid treatment of acute exacerbations of asthma

Eleven patients with chronic bronchial asthma were studied during a noninfectious exacerbation. Each patient received 80 mg of prednisone daily for three days. Spirometric values, total blood eosinophil counts, and 24-hour quantitation of sputum eosinophils were studied. Three patients had total blood eosinophil counts of less than 250 at the time of presentation. Statistical comparisons with findings on Day 0 showed significant improvements for the one-second forced expiratory volume, total blood eosinophil count, and sputum eosinophil number. On Day 7, the one-second forced expiratory volume maintained a statistically significant difference from that on Day 0, but the total blood eosinophil count did not. Analysis of correlation coefficients showed significant relation between the total blood eosinophil count and one-second forced expiratory volume, the sputum eosinophil count and one-second forced expiratory volume, and the sputum eosinophil and total blood eosinophil counts. The conclusions are (1) blood eosinophilia is not an invariable feature of acute exacerbations of asthma; (2) numbers of blood and sputum eosinophils reflect the response of an acute exacerbation of asthma to corticosteroids; (3) sputum eosinophils may be more meaningful for monitoring the stable postcorticosteroid state; (4) there is no support for the belief that eosinophils disappear from the sputum of asthmatic patients with clinically effective doses of corticosteroids.