Age-related changes in circulating immune factors reveal biomarkers of immunosenescence

Background: Immunosenescence, characterized by the decline and restructuring of immune system components with age, affects both innate and adaptive immunity. The predictive value of soluble factors in immunosenescence remains unclear. Objective: To investigate the predictive value of sCD28 (Soluble CD28), sCD40L (CD40 Ligand), sCD25 (Soluble CD25), IL-6 (Interleukin-6) and sPD-1 (Soluble Programmed Cell Death Protein 1) for immunosenescence in a general population, to evaluate their diagnostic potential using ROC curve analysis, including both individual and combined detection efficacy. Methods: = 28). Serum levels of sCD28, sCD40L, sCD25, IL-6, and sPD-1 were measured using ELISA. Baseline characteristics and correlations were analyzed using SPSS 25.0. ROC analysis was performed to assess diagnostic potential, with a focus on both individual markers and the combined detection of sPD-1, IL-6, and sCD28. Results: < 0.05). IL-6 had the highest individual AUC (0.77, 95%CI: 0.69-0.85; sensitivity 71%, specificity 78% at 1.22 pg./mL). Combined detection of sPD-1, IL-6, and sCD28 improved diagnostic performance, with an AUC of 0.82 (95%CI: 0.76-0.90), sensitivity of 70%, and specificity of 80% at a cut-off of 0.43. Conclusion: sPD-1, IL-6, and sCD28 are associated with immunosenescence and have diagnostic potential, with IL-6 showing the highest individual efficacy. Importantly, their combined detection enhances diagnostic accuracy for immunosenescence, highlighting their synergistic predictive value for immune aging.