CD71 is an integral membrane protein that mediates the uptake of transferrin-iron complexes. CD71 is a homodimeric glycoprotein that binds to diferric transferrin at the cell surface. It is most highly expressed on placental syncytiotrophoblasts, myocytes, basal keratinocytes, hepatocytes, endocrine pancreas, spermatocytes, and erythroid precursors. The maturation of erythroid precursors to erythrocytes results in loss of transferrin receptor expression, in concert with down-regulation of the machinery for hemoglobin synthesis. The high level of transferrin receptor within erythroid precursors makes it an excellent potential marker for evaluating erythroid elements within the bone marrow. CD71 has been studied for use in the assessment of leukemias and myelodysplastic syndromes (MDSs) in flow cytometric studies, in which expression serves as a lineage marker for the diagnosis of erythroid leukemia.
Anti-Human CD71 (OKT-9)-168Er—100 Tests