The anemia of thermal injury: mechanism of inhibition of erythropoiesis.

The anemia of thermal injury is a multifactorial process and includes hemorrhage and hemolysis. Much evidence suggests that a reduced rate of erythropoiesis contributes to this anemia. Prior studies show that this anemia is temporally related to the appearance in burn patients sera of a substance(s) capable of inhibiting erythropoiesis in vitro. Four experiments were done to elucidate the mechanism of action of this inhibitor. In all experiments sera from burn patients previously shown to be inhibitory to erythropoiesis in vitro were studied. In the first, inhibitory sera were exposed to erythropoietin solutions without loss of erythropoietic activity. Second, mouse marrow cells were preincubated with serum without loss of their ability to form erythroid colonies. Third, the inhibitory effect could not be overcome with increasing amounts of erythropoietin. Finally, erythroid colony formation was effected only if the inhibitory serum was present during the first 8 to 12 hr of culture. The data suggest that the erythropoietic inhibitor in these sera acts directly on erythroid stem cells in vitro and not by inactivating or interference with erythropoietin.