Restoration of lymphocyte numbers and immune function in Atm^-/- mutant mice reconstituted with C3H bone marrow cells. (A) Left panel: the frequency of CD4 T cells (left panel) in PBMCs of Atm^-/- mice (□), Atm^+/+ mice (▵), Atm^-/- mice reconstituted with C3H bone marrow (▿), and wild-type littermate controls receiving the BMT regimen (mock BMT, ⋄). Right panel: the frequency of CD8 T cells in PBMCs of Atm^-/- mice (▪), Atm^+/+ mice (▴), Atm^-/- mice receiving C3H bone marrow (▾), and wild-type littermate controls receiving the BMT regimen (mock BMT, ♦). Horizontal bars indicate arithmetic mean. (B) Left panel: rejection of B6.CH-2^bm1 skin grafts by unmodified Atm^-/- recipients (▴) and Atm^+/+ littermates (▪). Right panel: rejection of B6.CH-2^bm1 skin graft by Atm^-/- mice that received C3H transplanted bone marrow (▵) and mock BMT Atm^+/+ controls (□). Shown are the results of 1 of 2 experiments.