Variation of CD8+ T-lymphocytes around the bronchial internal perimeter in chronic bronchitis

The variation of CD8+ cells has been determined around the internal perimeter of intrapulmonary bronchi in smokers with chronic bronchitis (CB), and the amount of tissue required to confidently estimate the true mean has been calculated. Lung specimens were obtained from 10 smokers with CB. Paraffin sections of intrapulmonary bronchi were immunostained and CD8+ cells counted in the epithelium and subepithelium in up to 10 sequential 1-mm segments around the internal perimeter of each airway. The percentage of counts falling between +/-20% of the final mean was 43.0% for epithelium and 40.9% for subepithelium. In 90% of subjects, the cumulative mean was stable after examination of subepithelial tissue associated with 5 mm of reticular basement membrane. There is considerable variation in the counts of CD8+ cells between adjacent 1-mm airway mucosal segments in chronic bronchitis. In order to achieve a representative count and to maximise statistical power to detect differences between study populations, subepithelial tissue including a minimum of 5 mm of reticular basement membrane length should be examined.