Two Molecular Forms of Ferritin in Rabbit Marrow

Abstract

IN normal circumstances the bulk of iron bound to transferrin is delivered to the erythroid marrow for use in haemoglobin synthesis. Iron metabolism is conservative, however, and transferrin acquires its iron chiefly from storage depots in the reticuloendothelial system. The reticuloendothelial cells are responsible for the breakdown of red blood cells and for the salvage of iron which, after degradative breakdown of haemoglobin, is stored in these cells as ferritin. Transferrin again acquires this iron and transports it back to the erythroblasts, where it is incorporated both into ferritin and into haemoglobin. The factors which control the flow of iron from ferritin in reticuloendothelial cells to ferritin in erythroblasts are not understood. In this report, ferritin of reticuloendothelial cell origin, referred to as “catabolic” ferritin is distinguished from ferritin of erythroblasts, called here “anabolic” ferritin.