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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 Plasma IL-6, IL-8, IL-10, and IL-1β concentrations showed non-normal distributions. No significant differences were observed by sex or age (all P 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.
Yang et al. (2026) studied this question.