Age-related change in the number of T cells, CD8+T cells, CD8+CD28+T cells and TCPI in men and women. The slopes of T cells are -33.00 (a: men) versus -26.57 (b: women). The slopes of CD8+ T cells are -15.94 (c: men) versus -13.24 (d: women). The slopes of CD8+CD28+ T cells are -11.21 (e: men) versus -8.66 (f: women). The slopes of TCPI are -0.056 (g: men) versus -0.043 (h: women). Gender difference is observed in T cells (p = 0.049), CD8+CD28+ T cells (p = 0.04) and TCPI (p = 0.01).