THE EFFECT OF FILTRATION ON THE CELLULAR-COMPONENTS IN BRONCHOALVEOLAR LAVAGE FLUID

The effect of filtration through two layers of cotton gauze on the cel lular composition of bronchoalveolar lavage (BAL) fluid was studied in 25 patients wit pulmonary disease. There was no significant differenc e between median total cell count in unfiltered and filtered BAL (P=0. 73) or in the distribution of neutrophils or eosinophils. The percenta ge of bronchial epithelial cells was significantly higher in unfiltere d than in filtered BAL (P=0.02). Furthermore, differential cell counts showed a significantly lower percentage of alveolar macrophages (P=0. 04), and a significantly higher percentage of lymphocytes (P=0.04) in unfiltered compared with filtered BAL. Thus, gauze filtration results in a loss of bronchial epithelial cells and lymphocytes, and is not re commended in the routine analysis of cellular components in BAL fluid.