The CD71 antibody recognizes the transferrin receptor, which is essential for iron transport into proliferating cells. CD71 is expressed on marrow stromal cells (MSCs) from bone marrow, on activated T and B lymphocytes, macrophages, and all proliferating cells. It is upregulated on lymphocytes during proliferative responses to antigens or mitogens but is not expressed on resting lymphocytes. CD71 is present on reticulocytes and erythroid progenitors in fetal liver, cord blood, and peripheral blood, yet it is lost as these differentiate to mature erythrocytes.
Human cord blood mononuclear cells (CB MNCs) were stained with CD71 antibodies as well as with CD45 antibodies and analyzed by flow cytometry using the MACSQuant® Analyzer. The Tandem Signal Enhancer has been used to increase binding specificity of tandem-dye–conjugated antibodies. Cell debris and dead cells were excluded from the analysis based on scatter signals and propidium iodide fluorescence or 4',6-diamidino-2-phenylindole (DAPI) fluorescence, as in the case of tandems.