Materials and Methods Collection of Clinical Specimens
Bronchoalveolar lavage specimens were collected from patients undergoing diagnostic evaluation for suspected pulmonary disease, volunteers enrolled in a research protocol investigating HIV-positive patients without respiratory symptoms, and five normal volunteers. Only one patient of those from whom data were available (30 of 39 patients) was a smoker. No patients were mechanically ventilated, and none was receiving corticosteroids at the time of bronchoscopy. Clinical data on many of these patients previously have been reported. Patient recruitment, bronchoscopy, and data collection were performed under a protocol approved by the Clinical Research Subpanel of the National Institute of Allergy and Infectious Diseases.
Pre-bronchoscopic Pa02, Pco2, and fraction of inspired oxygen were noted; fiberoptic bronchoscopy was performed and BAL samples were collected as previously described. Bronchoalveolar lavage specimens were kept on ice until processing, usually within 30 min after bronchoscopy. After pooling all aliquots of collected fluid, 20 to 30 ml was sent for routine microbiologic and cytologic analysis and the remainder was processed as follows. Total leukocytes were enumerated by manual counting of an aliquot of uncentrifuged fluid with a hemocytometer. A differential leukocyte count was performed on slides prepared by cytocentrifugation and modified Wright staining (Diff-Quik, Baxter Healthcare Corp., Miami). Absolute neutrophil count was calculated from the total leukocyte count and differential cell count.