Objectives:  Use of domestic reference values is known to improve the accuracy of flow cytometric analysis by integrating local variation due to race, gender, and age. In the absence of previously published estimates, we now report establishment of reference values for a wide range of peripheral blood lymphocyte phenotypes applicable to the healthy adult population in Switzerland and other regions with similar demographic characteristics.

Methods:  A representative sample population was recruited from among well characterized local blood donors (n = 70) and quantitative multiparametric flow cytometry used to estimate absolute and proportional values for a range of T‐, B‐, and NK‐cell subsets, including those associated with activation and maturity. Distribution‐free methods were then applied to generate 95% reference values and to estimate the significance of gender and age‐related differences.

Results:  Reference values were obtained for the absolute and proportional levels of total CD3⁺ T cells (536–1787 cells/μL, 54.90–84.03%), helper CD4⁺ T cells (309–1139 cells/μL, 32.53–62.88%), cytotoxic CD8⁺ T cells (137–823 cells/μL, 11.55–38.60%), activated CD3⁺ T cells expressing CD25 (7–94 cells/μL, 0.50–5.95%), CD38 (102–554 cells/μL, 5.98–26.80%), HLA‐DR (18–186 cells/μL, 1.25–9.68%) or CD38/HLA‐DR (4–52 cells/μL, 0.30–2.30%), activated CD4⁺ T cells expressing CD25 (7–52 cells/μL, 0.33–2.80%), CD38 (69–547 cells/μL, 6.13–32.20%), HLA‐DR (11–55 cells/μL, 0.80–4.43%) or CD38/HLA‐DR (4–22 cells/μL, 0.30–1.35%), activated CD8⁺ T cells expressing CD25 (0–12 cells/μL, 0.00–0.69%), CD38 (13–124 cells/μL, 0.93–7.03%), HLA‐DR (6–108 cells/μL, 0.33–6.38%) or CD38/HLA‐DR (2–47 cells/μL, 0.13–2.68%), naive CD4⁺ T cells expressing CD45RA⁺/CD62L⁺ (84–761 cells/μL, 9.48–41.88%), naive CD8⁺ T cells expressing CD45RA⁺/CD62L⁺ (42–360 cells/μL, 3.68–19.23%), memory CD4⁺ T cells expressing CD45RO⁺ (247–807 cells/μL, 16.50–42.15%), memory CD8⁺ T cells expressing CD45RO⁺ (72–377 cells/μL, 3.78–22.80%), B‐cells expressing CD19 (72–460 cells/μL, 4.70–19.13%) or CD20 (66–529 cells/μL, 4.63–21.00%), total CD3⁻/(CD16⁺/CD56⁺) NK‐cells (77–427 cells/μL, 5.35–30.93%), and activated NK‐cells expressing CD25 (0–10 cells/μL, 0–0.50%) or HLA‐DR (3–99 cells/μL, 0.20–7.28%).

Conclusion:  It is anticipated that availability of localized reference values for an extended range of peripheral blood lymphocyte phenotypes should supplement previously published reference values and enhance the utility of flow cytometric analysis undertaken in Switzerland.