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Clinical and Diagnostic Laboratory Immunology, December 2005, p. 1416-1424, Vol. 12, No. 12
1071-412X/05/$08.00+0 doi:10.1128/CDLI.12.12.1416-1424.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Evaluation of a New Single-Parameter Volumetric Flow Cytometer (CyFlowgreen) for Enumeration of Absolute CD4+ T Lymphocytes in Human Immunodeficiency Virus Type 1-Infected Thai Patients
Kovit Pattanapanyasat,1* Surada Lerdwana,1 Egarit Noulsri,1 Thanyanan Chaowanachan,2 Punneeporn Wasinrapee,2 Natthaga Sakulploy,2 Vallerut Pobkeeree,2 Orapin Suksripanich,2 Sombat Thanprasertsuk,3 Thomas J. Spira,4 Jordan W. Tappero,5 and William C. Levine5Center of Excellence for Flow Cytometry, Office for Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand,1 Thailand Ministry of Public Health-U.S. CDC Collaboration, Nonthaburi, Thailand,2 Bureau of AIDS, TB and STIs, Department of Diseases Control, Ministry of Public Health, Nonthaburi, Thailand,3 Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia,4 Global AIDS Program, Centers for Disease Control and Prevention, Atlanta, Georgia5
Received 14 May 2005/ Returned for modification 29 July 2005/ Accepted 16 September 2005
Use of the standard dual-platform flow cytometric method for determination of CD4+ T-lymphocyte counts, which needs both a flow cytometer (FCM) and hematological analyzer, would inevitably lead to increased variability. The development of new single-platform (SP) FCMs that provide direct CD4+ T-lymphocyte counts for improved assay precision and accuracy have recently attracted attention. This study evaluated one of those systems, CyFlowgreen (Partec), a single-parameter SP volumetric FCM. The performance of CyFlowgreen was compared with those of two reference standard SP microbead-based technologies of the three-color TruCOUNT tube with the FACScan FCM and a two-color FACSCount system (Becton Dickinson Biosciences). Absolute CD4+ and CD8+ T-lymphocyte counts in 200 human immunodeficiency virus type 1-seropositive blood specimens were determined. Statistical analysis for correlation and agreement were performed. A high correlation of absolute CD4 counts was shown when those obtained with CyFlowgreen were compared with those obtained with the bead-based three-color TruCOUNT system (R2 = 0.96; mean bias, –69.1 cells/µl; 95% confidence interval [CI], –225.7 to +87.5 cells/µl) and the FACSCount system (R2 = 0.97; mean bias, –40.0 cells/µl; 95% CI, –165.1 to +85.1 cells/µl). The correlation of the CD4+ T-lymphocyte counts obtained by the two bead-based systems was high (R2 = 0.98). Interestingly, CyFlowgreen yielded CD4+ T-lymphocyte counts that were 21.8 and 7.2 cells/µl lower than those obtained with the TruCOUNT and the FACSCount systems, respectively, when CD4+ T-lymphocyte counts were <250 CD4+ T-lymphocyte counts/µl range or 17.3 and 5.8 cells/µl less, respectively, when CD4+ T-lymphocyte counts were <200 cells/µl. The single-parameter CyFlowgreen volumetric technology performed well in comparison with the performance of the standard SP bead-based FCM system. However, a multicenter comparative study is needed before this FCM machine is implemented in resource-limited settings.
* Corresponding author. Mailing address: Office for Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand. Phone: (662) 4197000. Fax: (662) 4110155. E-mail: grkpy{at}mahidol.ac.th.
Clinical and Diagnostic Laboratory Immunology, December 2005, p. 1416-1424, Vol. 12, No. 12
1071-412X/05/$08.00+0 doi:10.1128/CDLI.12.12.1416-1424.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
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