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Erythroblast transferrin receptors and transferrin kinetics in iron deficiency and various anemias
Author(s) -
Muta Koichiro,
Nishimura Junji,
Ideguchi Hiroshi,
Umemura Tsukuru,
Ibayashi Hiroshi
Publication year - 1987
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.2830250205
Subject(s) - transferrin , transferrin receptor , erythroblast , receptor , anemia , endocytosis , medicine , paroxysmal nocturnal hemoglobinuria , endocrinology , chemistry , erythropoiesis , immunology , biology , biochemistry
Abstract To clarify the role of transferrin receptors in cases of altered iron metabolism in clinical pathological conditions, we studied: 1 number of binding sites; 2 affinity; and 3 recycling kinetics of transferrin receptors on human erythroblasts. Since transferrin receptors are mainly present on erythroblasts, the number of surface transferrin receptors was determined by assay of binding of 125 I ‐transferrin and the percentage of erythroblasts in bone marrow mononuclear cells. 1 The number of binding sites on erythroblasts from patients with an iron deficiency anemia was significantly greater than in normal subjects (p < 0.01). Among those with an aplastic anemia, hemolytic anemia, myelodysplastic syndrome, and polycythemia vera compared to normal subjects, there were no considerable differences in the numbers of binding sites. 2 The dissociation constants (Kd) were measured using Scatchard analysis. The apparent Kd was unchanged (about 10 nmol/L in patients and normal subjects. 3 The kinetics of endocytosis and exocytosis of 125 I‐transferrin, examined by acid treatment, revealed no variations in recycling kinetics among the patients and normal subjects. These data suggest that iron uptake is regulated by modulation of the number of surface transferrin receptors, thereby reflecting the iron demand of the erythroblast.