Twenty-four hours after transplantation, NK and NK T cells accumulate in the spleen and BM, but not in the blood or liver, of NOD/SCID mice. CD56⁺ cells loaded with the fluorescent dye CFDA SE were injected into the tail veins of NOD/SCID mice. At 1, 4, 24, and 72 hours after injection, cells from the BM, spleen, liver, and blood were isolated. (A) The numbers of CD3⁺ NK T cells and NK cells in the BM (ii) and spleen (iii) were counted by FACS. Cells from the BM of uninjected mice are shown as a control (i). (B) The kinetics of homing (1 and 4 hours) and accumulation (24 and 72 hours) of NK and NK T cells detected in the BM (i) and spleen (ii). The presence of CD56⁺ cells in the blood and liver of injected mice is shown in panel iii. The results represent the average of 3 independent experiments ± SE.