biochimica clinica, 2013, vol. 37, n. 4 275 SCIENTIFIC PAPERS CONTRIBUTI SCIENTIFICI INTRODUZIONE Despite the critical role played in the clinical and therapeutic decision making of a variety of human disorders (1), cytometric analysis of biological fluids is still broadly performed by manual microscopy, which however requires skill personnel, has a low degree of inter-observer agreement, is time consuming and thereby frequently unavailable as stat testing. Some studies have recently assessed the accuracy of enumeration and differentiation of cells in biological fluids by means of automated flow cytometry, showing some important analytical drawbacks in this approach, mainly attributable to the relatively low number of corpuscular elements, which is seldom below the analytical sensitivity of most hemocytometers, and the presence of specific elements, such as macrophages and mesothelial cells, which are typically lacking in blood (2, 3). The aim of the present study was to compare the accuracy of cell counting and classification of total nucleated cells (TNC) in ascitic and pleural fluids between the hematological analyzer Sysmex XE-2100 and optical microscopy, as well as the diagnostic accuracy of polymorphonuclear leukocytes (PMN) and mononuclear cells count on Sysmex XE-2100, according to the Clinical Laboratory Standard Institute (CLSI) guideline H56-A (4). This document provides recommendations for numeration and identification of cellular components and guidance for qualitative and quantitative assessment for characterization of inflammatory, infectious, neoplastic and immune alterations of body fluids. We also assessed the novel control material for biological fluids Cell-Chex Auto (Streck Laboratories Inc.), prepared in three different levels from human cells for use on most hemocytometers, allowing daily quality check of leukocyte count in biological fluids. MATERIALS AND METHODS The Sysmex XE-2100 (commercialized in Italy by Dasit SpA) is a hematological analyzer that combines impedance and fluorescence flow cytometry for counting and differentiation of nucleated blood cells. The TNC count is derived from the white blood cell (WBC)-DIFF channel (service screen) that uses side scatter and fluorescence intensity after staining of nuclear DNA/RNA Evaluation of Sysmex XE-2100 for enumeration and differentiation of cellular elements in peritoneal and pleural fluids Sabrina Buoro 1 , Cosimo Ottomano 2 , Rosanna Gustinetti 1 , Cludia Galliani 1 , Eleonora Lochis 1 , Cheren Saleri 1 , Paola Dominoni 1 , Giuseppe Lippi 2 1 Laboratorio Analisi Chimico Cliniche, Azienda Ospedaliera Ospedali Riuniti, Bergamo 2 Unità Operativa di Diagnostica Ematochimica, Azienda Ospedaliero-Universitaria di Parma ABSTRACT The aim of this study was to evaluate the performance of Sysmex XE-2100 for automated flow cytometric analysis of biological fluids. The results of 106 consecutive peritoneal samples and 20 pleural samples were compared with optical microscopy. A good agreement was found in total nucleated cells (TNC) count between Sysmex XE-2100 and manual microscopy (y=0.98x+3.2, r=0.99; mean bias, -9.5 TNC/μL). The percentage of cells with high fluorescence in XE-2100 correlated with that of macrophages and mesothelial cells at microscopy (r=0.67; P <0.001). The CV of TNC determination on XE-2100 ranged between 1.6% and 11.7%. At the 20% CV, the analytical sensitivity of XE- 2100 was 29/μL for TNC, 50/μL for polymorphonuclear leukocytes (PMN) and 66/μL for mononuclear elements. The linearity between 30 and 944 TNC/μL was excellent (r=0.998, P <0.001), whereas the carry-over was <1%. At thresholds of ≥250 PMN/μL in peritoneal fluid and ≥50% PMN or ≥50% lymphocytes in pleural fluid, the diagnostic accuracy of XE-2100 was 96.8%, with Cohen's kappa of 0.90 (P <0.001). We conclude that automated flow cytometric analysis on Sysmex XE-2100 may be a viable options for screening of peritoneal and pleural fluids. Corrispondenza a: Sabrina Buoro, Laboratorio Analisi Chimico-Cliniche, Azienda Ospedaliera Papa Giovanni XXIII, Piazza OMS - Organizzazione Mondiale della Sanità 1, 24127 Bergamo. Tel. 0352674550, Fax 0352674939, E-mail sbuoro@hpg23.it Ricevuto: 11.12.2012 Revisionato: 22.01.2013 Accettato: 24.01.2013