Abstract
TransFix™ and Cyto-Chex® BCT (blood collection tube) reagents have been shown to maintain whole blood integrity for delayed immunophenotyping by flow cytometry. We evaluated the ability of these blood-stabilizing reagents to preserve HIV-seropositive blood for delayed CD4+ T-cell quantification utilizing the Dynal® Biotech T4 Quant Kit. TransFix was added to EDTA-anticoagulated whole blood and tested at a 1:10 dilution over 7 d using the Dynal (n = 21) manual method. Compared to baseline analysis, a significant decrease in mean CD4+ counts was observed over time. Cyto-Chex BCT–preserved samples (n = 20) were tested for CD4+ counts by Dynal over 7 d, with storage at varying temperatures: room temperature (21°C), 37°C, and 37°C with intermittent storage at 42°C. A significant decline in mean CD4+ counts was observed in samples at all temperatures compared to baseline (p < 0.05). Increases in temperature to and above 37°C resulted in a greater decline in mean CD4+ counts over time. Our findings indicated that neither TransFix or Cyto-Chex BCT was a suitable blood stabilizer when used for delayed CD4+ quantification with a low-cost manual CD4+ bead-based method.