title: Evaluation of a new single-parameter volumetric flow cytometer (CyFlow(green)) for enumeration of absolute CD4+ T lymphocytes in human immunodeficiency virus type 1-infected Thai patients.
abstract: 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, CyFlow(green) (Partec), a single-parameter SP volumetric FCM. The performance of CyFlow(green) 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 CyFlow(green) were compared with those obtained with the bead-based three-color TruCOUNT system (R(2)=0.96; mean bias, -69.1 cells/microl; 95% confidence interval [CI], -225.7 to+87.5 cells/microl) and the FACSCount system (R(2)=0.97; mean bias, -40.0 cells/microl; 95% CI, -165.1 to+85.1 cells/microl). The correlation of the CD4(+) T-lymphocyte counts obtained by the two bead-based systems was high (R(2)=0.98). Interestingly, CyFlow(green) yielded CD4(+) T-lymphocyte counts that were 21.8 and 7.2 cells/microl lower than those obtained with the TruCOUNT and the FACSCount systems, respectively, when CD4(+) T-lymphocyte counts were <250 CD4(+) T-lymphocyte counts/microl range or 17.3 and 5.8 cells/microl less, respectively, when CD4(+) T-lymphocyte counts were <200 cells/microl. The single-parameter CyFlow(green) 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.
authors.affiliation: Center of Excellence for Flow Cytometry, Office for Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand. grkpy@mahidol.ac.th
authors.forename: Kovit
authors.initials: K
authors.lastname: Pattanapanyasat
authors.forename: Surada
authors.initials: S
authors.lastname: Lerdwana
authors.forename: Egarit
authors.initials: E
authors.lastname: Noulsri
authors.forename: Thanyanan
authors.initials: T
authors.lastname: Chaowanachan
authors.forename: Punneeporn
authors.initials: P
authors.lastname: Wasinrapee
authors.forename: Natthaga
authors.initials: N
authors.lastname: Sakulploy
authors.forename: Vallerut
authors.initials: V
authors.lastname: Pobkeeree
authors.forename: Orapin
authors.initials: O
authors.lastname: Suksripanich
authors.forename: Sombat
authors.initials: S
authors.lastname: Thanprasertsuk
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Spira
authors.forename: Jordan W
authors.initials: JW
authors.lastname: Tappero
authors.forename: William C
authors.initials: WC
authors.lastname: Levine
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count / Q000379:methods*; D018414:CD8-Positive T-Lymphocytes; D005434:Flow Cytometry / Q000295:instrumentation / Q000379:methods*; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1; D006801:Humans; D016014:Linear Models; D018655:Lymphocyte Count / Q000379:methods; D011786:Quality Control; D015203:Reproducibility of Results; D013785:Thailand