If contaminated, the blood-tinged specimen was sent separately for microbiology. All specimens were sent for cell count and differential, and special stains for siderophages and lipid-laden macrophages. Stains and cultures were also obtained for bacteria, fungi, acid-fast mycobacteria, Legionella pneumophila, viruses, Chlamydia pneumoniae, and Mycoplasma pneumoniae. If indicated, a stain for Pneumocystis was also obtained.
The endobronchial specimens were coded and blindly examined by a single investigator (C.C.), preserved in formalin, processed, and embedded in paraffin. Routine histologic sections were cut at 5 pm and stained with hematoxylin-eosin. The presence of eosinophils was determined by their characteristic bilobed nucleus and eosin-staining granules within the cytoplasm. Pentachrome staining was also performed to better delineate the features of a remodeled airway. Specifically, each type of tissue stains a unique color. For example, smooth muscle stains red, collagen stains yellow, mucus stains turquoise, and elastin stains black. The thickness of the “total” basement membrane was assessed on two sections of the same biopsy sample (100 pm apart). Several estimates were made in each section stained with pentachrome, along its length at 200-pm intervals, and the values averaged. The measurements included both the true and reticular basement membrane. A semiquantitative scale was used a grade basement membrane thickness. A score of 3+ describes severe basement membrane thickening (> 10 pm), a score of 2 + describes moderate increase in basement membrane thickening (6 to 10 pm), while a score of 1+ describes mild thickening of the basement membrane (< 5 pm).
Results
The cohort studied included six children (three whites and three African Americans) evaluated at National Jewish Medical and Research Center (NJMRC) from 1993 to 1998 for evaluation of severe, persistent, steroid-dependent asthma and who underwent a clinically indicated bronchoscopy with endobronchial biopsy. The decision to perform bronchoscopy was at the discretion of the attending physician. The bronchoscopies were performed in every case to rule out other respiratory conditions and/or to evaluate for the presence inflammation despite aggressive inhaled and systemic glucocorticoid therapy.