Characteristics and reference ranges of CD4(+)T cell subpopulations among healthy adult Han Chinese in Shanxi Province, North China

BACKGROUND: Immunophenotyping of blood lymphocytes is an essential tool to evaluate the immune function of patients with immunodeficiency or autoimmunity. Predominately identified CD4(+)T cell subsets, Th1, Th2, Th17, as well as regulatory T (Treg) cells, play crucial roles in several immunological and pathological conditions. Considering the variations in cell counts among populations and ethnicities, specific CD4(+)T cell subset reference values need to be locally established to enable meaningful comparisons and accurate data interpretation in clinical and research settings. Therefore, the aim of this study was to establish distributions and reference ranges for blood CD4(+)T cell subpopulations in age- and sex-balanced healthy adults of a Han Chinese population in Shanxi Province, North China. METHODS: Peripheral blood CD4(+)T cell subsets were examined in 150 healthy volunteers (75 males, 75 females) aged 20–70 years with a four-color FACSCalibur flow cytometer. RESULTS: Reference value percentages (absolute counts, cells/μl) were defined as 95% of the population for cell types as follows: CD4(+)T, 23.78–51.07 (360–1127); Th1, 0.43–39.62 (2.64–276.21); Th2, 0.27–3.57 (1.80–27.14); Th17, 0.22–2.62 (1.10–19.54); and Treg, 2.17–7.94 (13.47–64.58). The ranges for the Th1:Th2 and Th17:Treg ratios were 0.59–52.37 and 0.04–0.76, respectively. Notably, a significant increase was observed in the values of Treg cells in older individuals, and the numbers of Treg cells in females also tended to decrease when compared to those in males. Therefore, we established the distribution and reference range of CD4(+)T cell subsets based on age and sex, demonstrating the lowest values of Treg cells in younger females. CONCLUSIONS: Collectively, our data provide population-, age-, and sex-specific distributions and reference ranges of circulating CD4(+)T cell subpopulations, which can be adopted to guide clinical decisions and interpretation of immunophenotyping data in the Han Chinese population in Taiyuan, Shanxi Province, China. In addition, the low expression of peripheral Treg cells in younger females may be associated with the predisposition of females to autoimmune diseases.