Fig. 1

Rate of CD4⁺ T cells and subsets change with age in vivo. a Rate of CD4⁺ T cells in peripheral blood in number of cells per μl blood. The rate of CD4⁺ 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. The linear regressions rate over time are -0.26 cell/μl/year (N = 165). b Rate of naïve CD4⁺ T cells in CD4⁺ T cells in number of cells per μl blood. The rate of naïve CD4⁺ T cell in cell/μl/year was based on flow cytometry analysis and lymphocyte counts from complete blood counts (N = 158). c Rate of regulatory CD4 T (Treg) cells in peripheral blood (N = 112). Treg was defined by expression of CD25 and Foxp3. d Rate of CD4⁺CD28^- T cells in peripheral blood (N = 160). P values were calculated by linear regression in this and subsequent figures