Age-associated remodeling of NK cell subsets, B cell subsets, and T cell surface markers in peripheral blood of healthy Chinese adults: a prospective multicolor flow cytometry study

Abstract

Background Immunosenescence refers to the structural and functional remodeling of the immune system that accompanies aging, and is closely linked to increased susceptibility to infection, diminished vaccine responses, and a higher burden of chronic disease. While flow cytometric profiling of peripheral blood lymphocyte subsets has become a key tool for characterizing immune aging, systematic age-related data on NK cell subsets (CD56hi/CD56dim/CD56neg three-way classification) and B cell subsets (IgD/CD27 four-way classification) in healthy Chinese adults remain scarce. Quantitative age trends for CD57 and TEMRA as markers of terminal T cell differentiation have also been incompletely described in this population. Methods We prospectively enrolled 146 healthy adults attending the annual health examination center of Peking Union Medical College Hospital (Panel 1: n = 103, age 20–82 years; Panel 2: n = 43, age 25–92 years, enriched for older participants). Panel 1 was a 12-color single-tube assay covering T cells (including CD57), NK cell trisubsets, and IgD/CD27-based B cell subsets. Panel 2 was a 12-color dual-tube assay focused on detailed T cell differentiation, incorporating CD45RA/CD62L, CD28, CD31, CD38, and HLA-DR. Spearman rank correlation, Kruskal–Wallis, and Mann-Whitney U tests were used for statistical analysis. Results In Panel 1 (n = 103), ten parameters showed significant age correlations. CD4+CD57+ (r = +0.421, p < 0.001) and CD8+CD57+ (r = +0.338, p < 0.001) rose most strongly with age. Total NK frequency increased (r = +0.259, p = 0.008) while CD56hiCD16− regulatory NK cells declined (r = −0.263, p = 0.007) and NK PD-1 expression rose (r = +0.256, p = 0.009). IgD+CD27+ marginal zone-like B cells declined significantly in Panel 1 (r = −0.257, p = 0.009). Panel 2 (n = 43) revealed the strongest signals in CD8+ T cells: TEMRA accumulation (r = +0.532), CD28 loss (r = −0.552), and naive depletion (r = −0.534) all reached p < 0.001. CD4+ naive cells also declined significantly (r = −0.303, p = 0.048). Multivariate analysis confirmed that most associations were independent of sex. Conclusion This study provides a comprehensive characterization of age-related immunophenotypic changes across NK cell subsets, IgD/CD27-defined B cell subsets, and multidimensional T cell markers in healthy Chinese adults, offering reference data for clinical immune assessment and vaccine response prediction.