Erythropoietic reserve in marrow-transplanted dogs.

The effect of marrow transplantation on erythropoiesis was studied in three normal dogs (T0), three irradiated dogs receiving compatible marrow (T1), and three irradiated dogs (T2) who donated their marrow to a recipient animal and then at a later date underwent a marrow transplant from the initial marrow recipient. Plasma iron turnover was measured (a) under basal conditions, (b) after plasma iron was elevated by iron infusion, and (c) after hemolytic anemia had been produced by phenylhydrazine. Basal plasma iron turnover in T0, T1, and T2 animals averaged 1.3, 1.0, and 1.3 mg/dl whole blood/day. Turnover of the three groups increased to 7.1, 6.2, and 6.4 mg/dl whole blood/day after the induction of anemia by phenylhydrazine. These values were converted from the transferrin saturation present at the time of the measurement to the calculated turnover at 100% saturation, thereby expressing the maximum capacity of tissues to assimilate iron. After this correction, the calculated maximum uptake was shown to be increased over basal by 3.7, 4.0, and 3.8 times. To validate this approach, an additional comparison was made between baseline turnovers at elevated levels of plasma iron and anemic animals at similarly elevated plasma iron levels. The increment of the three groups was shown to be 3.7, 3.9, and 4.0 times basal. These studies illustrate the use of a refined method of ferrokinetic evaluation of erythropoiesis and indicate that the proliferative reserve in transplanted animals is unimpaired.