Quantitative flow cytometric analysis of transferrin receptor expression on reticulocytes.

Background: A quantitative flow cytometric (FCM) method for transferrin receptor (TfR) expression on reticulocytes was developed and the results were compared with the markers of iron status.

Methods: A quantitative FCM analysis was performed using the Quantum Simply Cellular kit, according to which the antibody binding capacity (ABC) of TfR expression on reticulocytes was measured using a monoclonal antibody (CD71). Thiazole orange dye was used to identify reticulocytes. The proportion of TfR positive reticulocytes (%TfR(+)Ret) of all reticulocytes was also analyzed. The population consisted of 46 patients and 12 controls. Patients were categorized (based on Advia 120 cellular indices and serum iron status parameters) as having replete iron status, functional iron deficiency (FID), and as FID combined with depletion of iron stores (FID+ID).

Results: The TfR expression (ABC values) were higher in FID (1763+/-922, p<0.001) and FID+ID (1441+/-727, p=0.05) groups in comparison with the controls (663+/-110). Also, the %TfR(+)Rets were significantly higher in iron deficiency states than in controls.

Conclusions: The quantitative FCM method for TfR expression on reticulocytes was found to reflect iron status at the cellular level. The potential usefulness of this method should be evaluated further in larger and more defined study populations.