Long-term high expression of donor Hb following nonmyeloablative postnatal “booster” transplants in chimeric hemoglobinopathy mice. (A) Representive HPLC data, with donor Hb represented by the α2-globin level (green, cross-hatched peak), from chimeric SCD (left) and Thal (right) mice after postnatal boosting following 138 cGy TBI. Donor Hb expression in chimeric mice following IUHCT + boost at (B) 4 or (C) 32 weeks of age was assessed by HPLC. Donor Hb levels within each group (WT, Thal, and SCD) are statistically different (P < .05) following boosting compared with the nonboosted control at that time point with the exception of the points marked *. Donor Hb levels were statistically different at all time points following boosting within each group (WT, Thal, and SCD) between 0 cGy vs 138 cGy, and were statistically different when comparing levels at two sequential irradiation doses (ie, 0 cGy vs 82 cGy or 82 cGy vs 138 cGy) with the exception of those marked # (WT), $ (Thal), and & (SCD). Error bars expressed as SEM.