title: A multicenter evaluation of the PanLeucogating method and the use of generic monoclonal antibody reagents for CD4 enumeration in HIV-infected patients in Thailand.
abstract: BACKGROUND
  The current method of CD4 enumeration in Thailand, based on the three-tube, three-color method recommended by the Centers for Disease Control and Prevention, is expensive and thus unavailable to most patients who have the human immunodeficiency virus (HIV). Less expensive, simpler protocols (i.e., PanLeucogating and primary CD4 gating) have been described but require more published validation data to gain widespread acceptance. We describe a multicenter evaluation of the PanLeucogating method.
  
  
  METHODS
  The PanLeucogating method using generic reagents was evaluated in comparison with the standard three-tube, three-color method using commercial reagents. Percentage of CD4+ T cells among lymphocytes and absolute CD4+ T-cell counts were determined in 611 HIV-infected individuals recruited from four sites. Linear regression and Bland-Altman tests were used for statistical analysis.
  
  
  RESULTS
  The correlation of percentage of CD4+ T cells and absolute CD4+ T-cell counts obtained with the PanLeucogating strategy and the standard predicate method was high (r2 = 0.96 and 0.95, respectively, for the entire study population and r2 > 0.95 and 0.93, respectively, for each study group). Absolute CD4+ T-cell counts of the overall study pool and of the two subdivisions of absolute CD4+ T-cell counts (i.e., 0-250 cells/microl and > 250 cells/microl) derived from the two methods demonstrated excellent agreement, with mean biases of +18 cells/microl, +11 cells/microl, and +24 cells/microl, respectively.
  
  
  CONCLUSIONS
  These observations demonstrate that CD4 enumeration by PanLeucogating is reliable and can be performed to an identical standard in a quality-assured network of collaborating laboratories as a new cost-effective approach to HIV monitoring.
authors.affiliation: Center of Excellence for Flow Cytometry, Office for Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand. grkpy@mahidol.ac.th
authors.forename: Kovit
authors.initials: K
authors.lastname: Pattanapanyasat
authors.forename: Hla
authors.initials: H
authors.lastname: Shain
authors.forename: Egarit
authors.initials: E
authors.lastname: Noulsri
authors.forename: Surada
authors.initials: S
authors.lastname: Lerdwana
authors.forename: Charin
authors.initials: C
authors.lastname: Thepthai
authors.forename: Varipin
authors.initials: V
authors.lastname: Prasertsilpa
authors.forename: Sirirat
authors.initials: S
authors.lastname: Likanonsakul
authors.forename: Prakit
authors.initials: P
authors.lastname: Yothipitak
authors.forename: Somboon
authors.initials: S
authors.lastname: Nookhai
authors.forename: Achara
authors.initials: A
authors.lastname: Eksaengsri
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology* / Q000628:therapy; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D015704:CD4 Antigens / Q000032:analysis / Q000096:biosynthesis; D018791:CD4 Lymphocyte Count / Q000191:economics / Q000379:methods*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology; D003585:Cell Biology; D002452:Cell Count / Q000191:economics* / Q000379:methods*; D003362:Cost-Benefit Analysis; D006801:Humans; D016130:Immunophenotyping; D016014:Linear Models; D008214:Lymphocytes / Q000166:cytology; D015166:Monitoring, Immunologic / Q000379:methods; D011786:Quality Control; D013601:T-Lymphocytes / Q000166:cytology; D013785:Thailand
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens