Fumeng Yang, Ruoxue Cao, Fang Yang, Qian Liu, Wei Zhu
Background: Cytokines are central regulators of both physiological and pathological immune responses. In this study, flow cytometry was used to quantify plasma interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), and interleukin-1β (IL-1β), with the aim of establishing reference intervals to support clinical interpretation, diagnosis, and treatment. Methods: Between July and November 2025, 728 healthy adults from Jiangsu Province in eastern China were enrolled as reference individuals according to predefined inclusion and exclusion criteria. Plasma IL-6, IL-8, IL-10, and IL-1β concentrations were measured by flow cytometry. Data distribution was evaluated using the Kolmogorov-Smirnov test. In accordance with the Clinical and Laboratory Standards Institute (CLSI) C28-A3 and WS/T 402-2024, nonparametric reference intervals were established using the 95th percentile. Results: > 0.05); therefore, the entire cohort was analyzed as a single reference population. The resulting reference intervals, with 90% confidence intervals (CIs), were IL-6 ≤ 2.23 pg/mL (90% CI: 2.18-2.27 pg/mL), IL-8 ≤ 3.76 pg/mL (90% CI: 3.51-3.98 pg/mL), IL-10 ≤ 1.89 pg/mL (90% CI: 1.81-2.02 pg/mL), and IL-1β ≤ 1.34 pg/mL (90% CI: 1.17-1.39 pg/mL). Conclusion: To our knowledge, this is the first study to establish reference intervals for plasma IL-6, IL-8, IL-10, and IL-1β in a healthy adult population from Lianyungang, Jiangsu, eastern China. These intervals may provide a useful basis for evaluating immune status and for supporting the diagnosis and management of related clinical conditions.