Lymphocytes (T, B, NK, Treg, and naive T cells) in recipients and donors at transplant (15 recipient-donor pairs). (A) Absolute total lymphocyte (ALC), T-, B-, and NK-cell counts. (B) CD4⁺CD25⁺FOXP3⁺ regulatory T cells as a percentage of CD4⁺ T cells. (C) Paired analysis of naive (CD27⁺CD45RO⁻CD57⁻) CD4⁺ and CD8⁺ T cells in recipients and donors at SCT. (D) Paired analysis of naive CD4⁺ and CD8⁺ T cells in donors at SCT and donors in the second decade after SCT (9 pairs).