Recipients of G-PB grafts have faster T-cell reconstitution and thymopoiesis than BM graft recipients with more naive and TREC⁺ T cells. The proportions of CD4⁺ (A) and CD8⁺ (B) T cells with naive, central memory, effector memory, and terminal effector memory phenotype were determined by flow cytometry, as previously described,¹²  in blood samples obtained at 1, 3, 6, 12, and 24 months posttransplant from recipients of BM or G-PB grafts. Numbers of TREC⁺ CD4⁺ T cells (C) and TREC⁺ CD8⁺ T cells (D) per milliliter. (E) Percentages of TREC⁺ CD4⁺ naive T cells and TREC⁺ CD8⁺ naive T cells among recipients of BM or G-PB grafts. ***P < .001.