Studies on the Exchange of Iron between Transferrin and Reticulocytes

I ron is carried in the blood plasma very firmly bound to its specific carrying protein, transferrin, and in this form may be utilized for haemoglobin synthesis by reticulocytes (Walsh, Thomas, Chow, Fluharty and Finch, 1949) as well as by erythropoietic tissue of bone marrow. Although many workers have studied the exchange of iron between transferrin and reticulocytes (Paoletti, Boiron, Tubiana, Truhaut and Bernard, 1958; Jandl, Inman, Simmons and Allen, 1959; Allen and Jandl, 1960; Najean, Ardaillou and Bernard, 1960; Schade and Woodworth, 1961), knowledge of this process is still far from complete. Furthermore the results of various workers differ in certain important respects. For instance Jandl and associates (1959) found that iron uptake by reticulocytes varied with changes in transferrin concentration, while Schade and Woodworth (1961) found it to be independent of transferrin concentration. Similarly it is uncertain whether iron taken up by reticulocytes can (Pollycove and Maqsood, 1962) or cannot (Jandl et al. , 1959) be eluted by subsequent incubation with transferrin solutions. The present investigation was undertaken to provide further information on the mechanism of iron transfer from transferrin to reticulocytes and in an attempt to settle some of the differences in the results of previous workers. Rabbit reticulocytes, and rabbit plasma and rabbit transferrin purified by very mild procedures were used.