Human platelets express hemochromatosis protein (HFE) and transferrin receptor 2

Objectives: While body iron status may influence platelets, little information is available about platelet expression of proteins regulating iron homeostasis. HFE, the protein defective in hereditary hemochromatosis, and transferrin receptor 2 (TfR2) are two novel protein candidates that could be involved in mechanisms of iron transport across the platelet plasma membrane. Methods: The expression and localization of HFE, TfR1 and TfR2 proteins in human platelets were examined using Western blotting and immunocytochemistry. Results: Human platelets expressed HFE and TfR2, whereas no signal for TfR1 was found. The positive reactions for HFE and TfR2 were mainly confined to the platelet plasma membrane. Conclusions: Expression of HFE and TfR2 proteins in human platelets may indicate that the mutations in the corresponding genes could influence platelet count, size and/or activation. The presence of TfR2 and absence of TfR1 suggests that HFE may serve a different function in platelets compared with the other HFE-positive cell types, e.g. enterocytes, macrophages and syncytiotrophoblasts.