Corrected lymphocyte percentages reduce the differences in absolute CD4+T lymphocyte counts between dual-platform and single-platform flow cytometric approaches

Objective: To determine whether a corrected lymphocyte percentage could reduce bias in the absolute cluster of differentiation (CD)4+ T lymphocyte counts obtained via dual-platform (DP) vs standard single-platform (SP) flow cytometry. Methods: The correction factor (CF) for the lymphocyte percentages was calculated at 6 laboratories. The absolute CD4+ T lymphocyte counts in 300 blood specimens infected with human immunodeficiency virus (HIV) were determined using the DP and SP methods. Results: Applying the CFs revealed that 4 sites showed a decrease in the mean bias of absolute CD4+ T lymphocyte counts determined via DP vs standard SP (−109 vs −84 cells/μL, −80 vs −58 cells/μL, −52 vs −45 cells/μL, and −32 vs 1 cells/μL). However, 2 participating laboratories revealed an increase in the difference of the mean bias (−42 vs −49 cells/μL and −20 vs −69 cells/μL). Conclusions: Use of the corrected lymphocyte percentage shows potential for decreasing the difference in CD4 counts between DP and the standard SP method.