Cytocentrifugation conditions affecting the differential cell count in bronchoalveolar lavage fluid

OBJECTIVE: To investigate variations in speed, duration and acceleration ra te of the Cytospin 3 cytocentrifuge (Shannon, scientific Ltd., Astmoor, Eng land) on the differential cell count of bronchoalveolar lavage (BAL)fluid s amples. STUDY DESIGN: BAL fluid samples (n=51) were cytocentrifuged at various comb inations of speed (500, 1,200 and 2,000 rpm), acceleration rate (low, mediu m and high) and duration (5, 10, 15 and 20 minutes). The preparations were May-Grunwald-Giemsa stained and differentiated on 500 cells. Data were anal yzed try mixed model repeated measurements ANOVA. RESULTS: The mean lymphocyte count was significantly higher at 1,200 rpm th an at 500 rpm, whereas the macrophage count decreased. Between 1,200 and 2, 000 rpm, the number of both cell types stabilized. Significantly higher num bers of lymphocytes were recorded at 20 and 15 minutes of cytocentrifugatio n than at 5 minutes. The acceleration rate did not influence the differenti al cell count. Seventeen BAL fluid samples were selected to test the diagno stic impact of cell damage using a validated computer program. bz 1 of 17 s amples the predicted diagnosis did not correspond between two different spe eds (500 and 2,000 rpm). CONCLUSION: Variations in cytocentrifugation speed and duration affected th e mean lymphocyte and macrophage counts of BAL fluid samples.