Analyses of sequential bronchoalveolar lavage samples from healthy human volunteers

Subsegmental bronchoalveolar lavage of human subjects provides an accessible sample of cells and secretions from the lower respiratory tract for clinical and research study. Technical factors that may modify lavage results have received little attention. The effects of lavage volume on the patterns of recovered cells and biochemical components were studied by separately analyzing each of 4 sequential 60-ml syringes of saline instilled into a subsegment of the right middle lobe. Fourteen healthy normal subjects volunteered for lavage. Recovery of cells from both nonsmokers and smokers increased and then remained essentially constant in subsequent syringes, suggesting elution of adherent macrophages from the alveolar surface. Protein, carbohydrate, lipid, and potassium appeared in decreasing concentrations in sequential syringes, but different constituents followed separate patterns. Simple mixing models do not explain the observed results. Measured values for the components in a "small" 120-ml lavage may be substantially different from the values in a "large" 240-ml lavage. Further study of the kinetics of recovery of selected lavage components may provide better understanding of the origins and functions of these substances in the lung.