Effect of polymeric plutonium on the hematopoietic activity in the bone marrow of mice

The hematopoietic activity in the bone marrow was investigated in male CF No.1 mice at 28 and 56 days after intravenous injection of polymeric plutonium-239 at the dose level of 15 μCi/kg, 10 μCi/kg and 5 μCi/kg of body weight. The number of nucleated cells in the femoral marrow decreased in proportion to the amount of plutonium injected. The number of in vivo colony forming units per femoral marrow also decreased with the increase of the dose of plutonium. No significant change was observed in the blood clearance of 59Fe with the exception of the group at 56 days after injection of the heighest dose. In this group 59Fe in the blood disappeared very rapidly within 2 minutes after injection of 59Fe. With the injection of plutonium, 59Fe incorporation into circulating erythrocytes was depressed even in the lowest dose group. Except for the group at 56 days after injection of the highest dose, 59Fe in the femur increased. The possibility of ineffective erythropoiesis by polymeric plutonium was discussed. From the facts investigated in this study, we may conclude that the hematological activity in the bone marrow was disturbed by as low as 5 μCi/kg of polymeric plutonium, the dose with which clinically detectable anemia had not been induced. (author)