Bronchial biopsies and airway inflammation

107

We do not have an estimate of how much tissue is needed for a reliable measure of bronchial epithelial reticular basement membrane (RBM) thickness or for counts of inflammatory cells. An assessment of the frequency distribution and variance of data from repeat measurements of RBM thickness and biopsy section inflammatory cell counts in cases with asthma (n=6), chronic obstructive pulmonary disease (COPD; n=5), and normal healthy subjects (n=7) was made. Tissue sections were stained with haematoxylin and eosin or by immunohistochemistry for EG2, mast cell tryptase and CD3-positive cells. Measurements of RBM thickness in individuals followed a log-normal distribution. For a precision of approximately +/-15%, 31-45 measurements were required. In contrast, inflammatory cell counts for each individual did not follow a normal distribution. There was high variance such that the cumulative weighted mean did not become stable until at least 5-10 mm of tissue underlying the RBM had been included. In conclusion multiple measurements of reticular basement membrane thickness or tissue section cell counts should be made for each individual in studies of bronchial biopsies. It is recommended that reticular basement membrane thickness should be measured at 20 mm intervals over a 1 mm reticular basement membrane length and that a zone beneath it of at least 5-10 mm of reticular basement membrane should be included for counts of inflammatory cells.

Section: Discussionmentioning

confidence: 99%

Section: Variation In the Measurements Of Basement Membrane Thicknessmentioning

confidence: 99%

Variation in the measurements of basement membrane thickness and inflammatory cell number in bronchial biopsies

Sullivan¹,

Stephens²,

Ansari³

et al. 1998

107

“…Such scoring methods seem to provide satisfactory reproducibility and good agreement with computerized video interactive quantification of inflammatory cells in bronchial biopsies [28]. Obviously, further research is needed to optimize the quantification of the cellular infiltrate, because bronchial biopsy specimens will remain the gold standard for assessing airway inflammation in asthma [29].…”

Section: Discussionmentioning

confidence: 99%

Repeatability of measures of inflammatory cell number in bronchial biopsies in atopic asthma

Sont

Willems²,

Evertse³

et al. 1997

Airway pathology is increasingly considered to be a major outcome in asthma research. The aim of this study was to examine the intra-observer, within-section and between-biopsy repeatability, together with the implications for statistical power of a computerized quantitative analysis of inflammatory cell numbers in the lamina propria in bronchial biopsy specimens from atopic asthmatic subjects.Thirty six atopic adults (aged 19-40 yrs) with mild to moderate asthma (baseline forced expiratory volume in one second (FEV1) ≥50% of predicted value, methacholine (PC20) range 0.02-18.2 mg·mL -1 ) at various levels of treatment (25 subjects on inhaled steroids) entered the study. Biopsies were taken from the (sub)segmental carinae of the right lower and middle lobe and from the main carina. Specimens were snap-frozen and immunohistochemical staining was performed on cryostat sections with monoclonal antibodies against: (secreted) eosinophil cationic protein (EG1, EG2), mast cell tryptase (AA1), CD45, CD22, CD4, CD8, CD25, and CD45RO. Using a computerized system, the number of positively stained cells in the lamina propria was counted.When considering all cell types together, satisfactory intraclass correlation coefficients (ICC) values were obtained for intra-observer, within-section and betweenbiopsy repeatability, being 0.90, 0.80 and 0.81, respectively. The analysis of repeatability for individual cell types revealed ICC values ranging 0.47-0.82 for intra-observer, 0.44-0.76 for within-section and 0.37-0.67 for between-biopsy repeatability. The results imply that a sample-size between eight and 25 subjects is needed to detect at least one doubling difference in cell number per 0.1 mm 2 for a particular inflammatory cell type in a study, using a within-group design with α=0.05 and power of 0.80. A sample-size of 13-48 subjects per group is required to detect the same difference between the groups in a parallel design.

“…Studies using bronchial biopsies and bronchoalveolar lavage have demonstrated increased infiltration of eosinophils, mast cells and lymphocytes in the airways of subjects with asthma [2]. However, bronchoscopy is an invasive procedure, especially in children, and use is therefore restricted to adult patients with mild forms of asthma [3].…”

mentioning

confidence: 99%

Induced sputum in adolescents with severe stable asthma. Safety and the relationship of cell counts and eosinophil cationic protein to clinical severity

Grootendorst¹,

Bos²,

Romeijn³

et al. 1999

This study examined the safety of sputum induction and the relation between sputum cell counts and clinical parameters in adolescents with severe persistent asthma.Within 5 days, induced sputum and reversibility in forced expiratory volume in one second (FEV1), quality of life, provocative concentration causing a 20% fall in FEV1 (PC20) of adenosine monophosphate and histamine, exercise-induced bronchoconstriction, overall asthma severity index, and blood eosinophils were collected in 20 atopic adolescents with moderate-to-severe persistent asthma (12±18 yrs of age, FEV1 65±110% of predicted, on 500±2,000 mg inhaled steroids daily).FEV1 was reversible by 13.32.3% pred. After sputum induction, FEV1 was still increased by 9.02.6% pred as compared to the pre-salbutamol baseline. Sputum contained, median (range): 12.4 (0.4±59.5)% squamous cells, 47.3 (6.8±84.0)% macrophages, 39.0 (4.6±84.8)% neutrophils, 4.8 (1.0±12.4)% lymphocytes, 0.4 (0±10.8)% eosinophils and 3.6 (0±23.4)% bronchial epithelial cells. Sputum eosinophils showed a trend towards a significant association with the overall asthma severity index (r=0.46, p=0.06) and correlated inversely with baseline FEV1 (r=-0.51, p=0.03).In conclusion, sputum can be induced safely in adolescents with moderate-to-severe persistent asthma, if pretreated with b 2 -agonists. Despite relatively low sputum eosinophil counts in these patients on inhaled steroids, the association of eosinophil numbers with baseline forced expiratory volume in one second and asthma severity index favours a role of induced sputum in monitoring adolescents with severe asthma. Eur Respir J 1999; 13: 647±653.