Determination of lymphocyte subset reference ranges in peripheral blood of healthy adults by a dual-platform flow cytometry method

Flow cytometry has emerged as a useful screening approach to evaluate whether specific cell populations are present or absent. Previous studies have shown different reference ranges in several countries. The aim of this study was to determine reference ranges of lymphocyte subsets in peripheral blood by flow cytometric method in Brazilian adults. In this study, relative and absolute reference ranges of lymphocyte subsets were: CD3+: 51.3-83.5%, 718-2494 cells/μl; CD4+: 24.4-54.2%, 456-1492 cells/μl; CD8+: 12.8-40.2%, 272-1144 cells/μl; CD4+CD8+: double-positive 0.01-3.6%, 2-88 cells/μl; TCR γδ: 1.0-15.9%, 19-345 cells/μl; CD3+CD4−CD8−: 1.2-13.3%, 28-292 cells/μl; TCR αβ+: 44.3-77.0%, 855-2384 cells/μl; CD4/CD8 ratio: 0.68-3.61; CD19+: 6.3-20.8%, 112-622 cells/μl; mature NK cells: 3.1-27.4%, 70-745 cells/μl; immature NK cells: 0.08-1.1%, 1-23 cells/μl; total NK cells: 3.7-28.5%, 82-760 cells/μl; and NKT cells: 0.9-21.4%, 18-488 cells/μl. Comparison with other studies showed differences among some of them. This suggests that there are differences among lymphocyte subsets in the worldwide population and also it is important to determine reference ranges in different populations in order to better assess and monitor patients.