Evaluation of Stabilized Blood Cell Products as Candidate Preparations for Quality Assessment Programs for CD4 T-Cell Counting

Background: Exceptionally robust cell preparations are needed for quality assessment programs (QAPs) such as the International Program for Quality Assessment and Standardization for Immunological Measures (QASI) relevant to HIV/AIDS. A suitable product must withstand environmental stress related to transportation for a minimum of 6 days. The two objectives of this study are (1) to evaluate the performance of various commercial preparations with multicenter participation and (2) to evaluate the robustness of stabilized blood cell products. Methods: Phase 1: The performance of stabilized blood cell products was evaluated in a multicenter QAP utilizing various staining procedures and flow cytometers. Absolute cell enumeration was achieved using single-platform T-cell subset methodology. Phase 2: The robustness of stabilized blood cell products was evaluated by monitoring T-cell subset values from samples stored at 4°C, 22°C, and 37°C for up to 10 days. Results: The largest interlaboratory variation in both absolute and relative T-cell values was 16% in samples with CD4 levels >400 cells per microliter and 21% in samples with CD4 levels <400 cells per microliter. Six preparations retained their phenotypic expression for 7 days at 4°C and 22°C. However, only two preparations remained stable for 4 days at 37°C. Conclusion: Some stabilized cell preparations are more robust and therefore more suitable for quality assessment purposes. Cytometry (Clin. Cytometry) 50: 86 ‐91, 2002. © 2002 Wiley-Liss, Inc.