CONTRASTING UPTAKES OF FE-59 INTO SPLEEN, LIVER, KIDNEY AND SOME OTHER SOFT-TISSUES IN NORMAL AND HYPOTRANSFERRINAEMIC MICE - INFLUENCE OF AN ANTIBODY AGAINST THE TRANSFERRIN RECEPTOR

Uptake of iron-59 from blood into various soft tissues of anaesthetized mice was investigated by continuous intravenous infusion of the radiotracer during 2 hr. The Fe-59 was given either as ferrous chloride with ascorbate or as Fe-59-transferrin. Infusions were made into adult mice with and without pretreatment with a monoclonal antibody against transferrin receptors, and into hypotransferrinaemic mice and appropriate controls. In normal mice, Fe-59 uptake into spleen was much higher than into other tissues and was 94-96% inhibited by the antibody. Inhibitions due to the antibody were less complete in liver and renal cortex, and there was evidence of some non-transferrin-mediated transport during infusion of Fe-59/ascorbate. In the hypotransferrinaemic mice, tissue uptakes of Fe-59 during infusion of Fe-59/ascorbate were enormous, being two to three orders of magnitude greater than in the normal controls. The rank order for size of uptake was liver > renal cortex > pancreas > spleen > other tissues. All tissues examined have a considerable potential capacity for uptake of non-transferrin-bound iron, this being greatest in liver and renal cortex.