Manual and automated leukocyte differentiation in bronchoalveolar lavage fluids from rodent models of pulmonary inflammation

Manual total and differential leukocyte counting in bronchoalveolar lavage fluids (BALF) by visual microscopy is a standard means of evaluating airway inflammation and the anti-inflammatory properties of therapeutics in various animal models of lung disease. The manual cell counting method derives total leukocyte counts from BALF with a hemocytometer, and cell differentials (mononuclear, neutrophil, eosinophil) are calculated from the percentage of each cell type taken from a count of at least 200 cells on a stained cytocentrifuge preparation of the BALF cells. These manual methods are time-consuming and have inherent error–variability. The ADVIA 120 Hematology System is an automated analyzer designed to perform total and differential leukocyte analysis of blood. With the light scattering, cell lysis resistance, and cytochemical staining data from a BALF sample processed by the ADIVA, a BALF total leukocyte count and differential analysis is provided in approximately 30 s. In order to correlate automated BALF leukocyte counting by the ADVIA 120 Hematology System with manual counting, we developed a manual red blood cell lysing and white blood cell staining technique for BALF cells similar to the process used by the ADVIA. Significant correlations for BALF white blood cells were obtained for the manual (microscopic analysis) and the automated (ADVIA) methods. Comparison of manual and automated cell counts also generates the same conclusions about anti-inflammatory drug efficacy. Both manual and automated cell counting methods agree that 3 mg/kg orally administered dexamethasone inhibited cigarette-smoke-induced total BALF cell counts by ∼65% in mice and 42 μg/kg fluticasone propionate delivered by nose-only inhalation inhibited allergen-induced total BALF cells by 77% in rats. The use of the ADVIA to perform total and differential leukocyte counts in BALF will save time spent manually counting cells and this instrument will standardize the analysis of white blood cells across the laboratories currently using various manual counting preparations and procedures.