1991 Volume 103 Issue 5-6 Pages 645-657
A novel method was developed to investigate the mechanisms about the transferrin receptor (TfR) expression in human erythroid cells. Human bone marrow smear was reacted with OKT9 monoclonal antibody to measure TfR on a single erythroid cell using K562 cells as an inner control. TfRs detected by OKT9 were visualized by autoradiography. The maturational stage and stainable iron granules (SIGs) of erythroid cells were identified by Wright Giemsa staining method and iron staining method alternately. Using this method, the following results were obtained. TfR was expressed on immature erythroid cells from proerythroblasts to immature RBC, with a decreased number occurring during erythroid maturation, and was absent on mature red cells. Maximal density of TfR occurred at the proerythroblast stage and then decreased progressively during maturation to immature RBC. It is assumed that cell maturation had a suppressive effect on TfR expression. The mean number of TfRs on erythroblasts was obviously higher in iron deficiency, and lower in iron overload. Although stainable iron granules had no manifest correlation with TfR number on each erythroid cell within each patient, there was a negative correlation between the mean number of TfRs and that of SIGs obtained from each donor (r=-0.89). The same correlation was obtained between mean density of TfRs and that of SIGs. These findings indicate that, in the human erythroid cell, cell maturation may be a key regulatory factor than stainable iron granules in TfR expression of erythroid cell. However, when examined in different iron environments, the mean stainable iron granule which may be regarded as one measurable form of iron state clearly correlated negatively with the state of TfR expression.
