Fig. 2

Rate of CD8⁺ T cells and subsets change with age in vivo. a Rate of CD8⁺ T cells in peripheral blood in number of cells per μl blood (N = 162). The rate of CD8⁺ T cells was calculated based on flow cytometry analysis using the gating strategy described in (Additional file 1: Figure S1) and lymphocyte counts from complete blood counts. b Rate of naïve CD8⁺ T cells in CD8⁺ T cell in cell number per μl blood (N = 159). Naïve CD8⁺ T cell were defined by CD45RA⁺/CD28⁺. c Rate of CD8⁺CD28^- T cells in CD8⁺ T cell in cell number per μl blood (N = 162). d Ratio of CD4⁺/CD8⁺ T cells (number of cells/μl) as a function of age (N = 162). P values were calculated by linear regression in this and subsequent figures