Figure 2. Correlation analysis between different lymphocyte parameters and age. (A) Heparinized peripheral blood was collected from study participants. The percentages and absolute numbers of CD4+ T cells, CD8+ T cells, B cells and NK cells were determined by flow cytometry. Correlation between lymphocyte count (including percentage and absolute number) and age. (B) PMA/ionomycin-stimulated lymphocyte function assay was performed in study participants. Correlation between lymphocyte function (including CD4+ T cells, CD8+ T cells, and NK cells) and age. (C) The expression of phenotype markers CD28, HLA-DR, and CD45RO on CD4+ and CD8+ T cells was analyzed by flow cytometry. Correlation between these phenotype markers and age. Each symbol represents an individual donor.