Administration of anti–IL-7Rα antibody results in decreased numbers of donor T cells in the periphery following allogeneic BMT. Analyses of donor-derived peripheral CD4 and CD8 T-cell numbers in anti–IL-7Rα antibody and PBS-treated B6 recipients were performed at day 10 and 30 following allogeneic BMT and LN-cell transplantation. Shown are numbers of donor T lymphocytes at day 10 and day 30 in spleen (A) and LN (B). Asterisk indicates significant differences between PBS- and anti–IL-7Rα-treated groups (spleen and LN at day 10, P < .02; spleen at day 30, P < .02).