Fig. 2

Percentage of peripheral monocyte subsets from young, middle-aged, and older adults. A. Ideograph and representative flow cytometry analyses of monocytes. According to the expression pattern of CD14 and CD16, human monocytes were divided into CD14^lowCD16⁻ (Mo0), CD14^highCD16⁻ (Mo1), CD14^highCD16⁺ (Mo2), and CD14^low CD16⁺ (Mo3) subsets. B. Comparison of the percentages of Mo0, Mo1, Mo2, and Mo3 subpopulations among all monocytes in young, middle-aged, and older adults were performed according to the expression pattern of CD14 and CD16 (young: 21–40 years, n = 42; middle-aged: 41–60 years, n = 34; older: > 60 years, n = 34). P-values were calculated using the non-parametric Kruskal–Wallis rank test, followed by post hoc analysis