Assessment of EQA Reference Conventional Flow Cytometers for Clinical CD4+ T-Cell Enumeration

Authors

  • Ahmed J National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada Author
  • Saliga G National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada Author
  • Meyers AFA Laboratory Integration, Office of Population and Public Health, Indigenous Service Canada, Ottawa, Canada Author
  • Ball BT Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada Author
  • Sandstrom P Laboratory Integration, Office of Population and Public Health, Indigenous Service Canada, Ottawa, Canada Author
  • Kiazyk S Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada Author
  • Diallo TO National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada Author

DOI:

https://doi.org/10.47363/JIDSCR/2026(7)207

Keywords:

Conventional Flow Cytometer, Instrument, Quality Control, CD4 Testing, Immunophenotyping, HIV

Abstract

Background: CD4+ T-cell enumeration continues to be an essential marker for assessing immunodeficiency and monitoring HIV disease progression. Enrollment in an external quality assessment (EQA) program is a strong tool for diagnostics as it allows for identification and correction of potential errors that may occur during testing. The aim of this article is to investigate the effect of our repeated participation in an EQA program on the performance of our internal flow cytometry instruments, namely the Navios and FACSCalibur, as an EQA provider.

Methods: We compiled data from 14 Canadian Immunology Quality Assurance Program (CIQAP) EQA sessions and compared the Navios and FACSCalibur results to the aggregate group mean (AGM) of each session. The standard deviation index (SDI), residual, and percent differential was performed to identify trends in data and identify any potential problems. A Bland-Altman analysis was performed comparing both of these flow cytometry instruments.

Results: Our results showed good performance overall with trend variation between the relative (%) and absolute count CD4+ T-cell results for both of the instruments. We observed a good agreement between instruments and identified that all HIV+ samples with low relative CD4+ T-cell results (<28%) were overestimated by Navios compared to FACSCalibur.

Conclusion: As an EQA coordinator, using the same instruments as participating laboratories allows more accurate monitoring of instrument performance and variability, supporting a stronger analysis of corrective action based on participant results.

Author Biographies

  • Ahmed J, National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada

    National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada

  • Saliga G, National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada

    National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada

  • Meyers AFA, Laboratory Integration, Office of Population and Public Health, Indigenous Service Canada, Ottawa, Canada

    Laboratory Integration, Office of Population and Public Health, Indigenous Service Canada, Ottawa, Canada

  • Ball BT, Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada

    Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada

  • Sandstrom P, Laboratory Integration, Office of Population and Public Health, Indigenous Service Canada, Ottawa, Canada

    Laboratory Integration, Office of Population and Public Health, Indigenous Service Canada, Ottawa, Canada

  • Kiazyk S, Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada

    Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada

  • Diallo TO, National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada

    National Sexually Transmitted and Blood-Borne Infections Laboratories, JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, Canada

Downloads

Published

2026-05-05

Issue

Vol. 7 No. 2 (2026): Volume 7 Issue 2

Section

Articles