Percentages of CD4+CD8+ Double-positive T Lymphocytes in the Peripheral Blood of Adults from a Blood Bank in Bogotá, Colombia

OBJECTIVE: CD4+CD8+ double-positive T-cells (DPTs) have been classified as a separate T-cell subpopulation, with two main phenotypes: CD4(high) CD8(low) and CD4(low) CD8(high). In recent years, the relevance of DPTs in the pathogenesis of infections, tumors, and autoimmune diseases has been recognized. Reference values among healthy individuals remain unknown. Therefore, the aim of this study is to provide a reference value for DPTs in peripheral blood from healthy donors in a blood bank in Bogotá, Colombia, and to determine the activation status using a surface marker. MATERIALS AND METHODS: One hundred healthy donors were enrolled in the study. Peripheral blood cells were stained for CD3, CD4, CD8, and CD154 (CD40L), and cellular viability was assessed with 7-aminoactinomycin D and analyzed by flow cytometry. RESULTS: The median value for DPTs was 2.6% (interquartile range=1.70%-3.67%). Women had higher percentages of DPTs than men (3.3% vs. 2.1%). The subpopulation of CD4(low) CD8(high) showed higher expression of CD154 than the other T-cell subpopulations. CONCLUSION: DPT reference values were obtained from blood bank donors. A sex difference was found, and the CD4(low) CD8(high) subpopulation had the highest activation marker expression.