Variation of differential cell counts of bronchoalveolar lavage fluid.

Bronchoalveolar lavage (BAL) is a common research and clinical tool to retrieve cells from the lower respiratory tract. Differential cell counts of the nucleated cells retrieved by BAL provide important diagnostic and prognostic information. There is much variation between laboratories in the reported normal percentages of lymphocytes and macrophages of cells retrieved by BAL. We compared three methods of identifying cells in the BAL fluid: a modified Wright-Giemsa (WG) stain, a nonspecific esterase stain, and a monoclonal marker for T lymphocytes. There was good agreement between the percentage of macrophages identified by WG and nonspecific esterase and the percentage of lymphocytes determined by WG stain and monoclonal marker. Intrasubject and intersubject agreement of the differential cell counts determined by the WG stain was good. We concluded that cells from BAL fluid can be analyzed using the WG stain alone.