IUHSCT followed by a postnatal low-dose TBI/BMT regimen results in high levels of allochimerism.

Chimeric mice after IUHSCT received 1 of 4 doses of TBI followed by a postnatal TCD BM transplantation with cells congenic (B6Pep3b) to the allogeneic prenatal donor at 4 (A) or 8 (B) weeks of age. Control mice were 4-week-old naive Balb/c males that received 276 cGy TBI followed by tail vein infusion of 30 × 10⁶ TCD B6 BM cells. At all time points there is no difference between chimerism levels in mice boosted at 8 and 4 weeks of age (P < .05) with the exception of the two marked points (*). Levels of chimerism were statistically different between each irradiation dose with the exception of the # marked point where P < .05.