Labile iron, ROS, and cell death are prominently induced by haemin, but not by non-transferrin-bound iron.

BACKGROUND: In transfusion-related iron overload, haem-derived iron accumulation in monocytes/macrophages is the initial event. When iron loading exceeds the ferritin storage capacity, iron is released into the plasma. When iron loading exceeds transferrin binding capacity, labile, non-transferrin-bound iron (NTBI) appears and causes organ injury. Haemin-induced cell death has already been investigated; however, whether NTBI induces cell death in monocytes/macrophages remains unclear. MATERIAL AND METHODS: Human monocytic THP-1 cells were treated with haemin or NTBI, particularly ferric ammonium citrate (FAC) or ferrous ammonium sulfate (FAS). The intracellular labile iron pool (LIP) was measured using an iron-sensitive fluorescent probe. Ferritin expression was measured by western blotting. RESULTS: LIP was elevated after haemin treatment but not after FAC or FAS treatment. Reactive oxygen species (ROS) generation and cell death induction were remarkable after haemin treatment but not after FAC or FAS treatment. Ferritin expression was not different between the FAC and haemin treatments. The combination of an iron chelator and a ferroptosis inhibitor significantly augmented the suppression of haemin cytotoxicity (p = 0.011). DISCUSSION: The difference in LIP suggests the different iron traffic mechanisms for haem-derived iron and NTBI. The Combination of iron chelators and antioxidants is beneficial for iron overload therapy.

Deferasirox reduces oxidative stress in patients with transfusion dependency.

BACKGROUND: Iron chelation therapy is useful against the over-accumulation of iron and is expected to reduce oxidative stress resulting from the Fenton reaction and Haber-Weiss reaction. We monitored oxidative status and serum ferritin levels after in vivo administration of deferasirox (DFS) and studied the in vitro effects of iron chelators on neutrophil function. METHODS: Nine patients suffering from transfusion dependency were recruited for this study, and derivatives of reactive oxygen metabolite (dROM) tests to detect serum hydroperoxide levels were evaluated in addition to serum ferritin levels. Human neutrophil reactive oxygen species (ROS) production was determined with flow cytometry. RESULTS: Ferritin levels decreased after DFS treatment (P = 0.068), and a significant reduction in dROM levels was measured (P = 0.031). Fifty microM DFS significantly inhibited ROS production induced by fMLP in vitro (P < 0.0001), and tended to inhibit that induced by PMA. On the other hand, deferioxamine failed to inhibit ROS production even at high concentrations. CONCLUSIONS: In vivo administration of DFS resulted in the reduction of oxidative stress, and this effect was considered to depend not only on a reduction in iron storage but also on the ability of DFS to inhibit neutrophil ROS production in vitro at clinically relevant plasma levels. Further studies are needed to examine the effects of iron chelators.

[Laboratory medicine for blood transfusion and transplantation medicine].

We discussed the usefulness of routine technologies of laboratory medicine in blood transfusion and transplantation medicine. New parameters that can be measured by automated hematology analyzers have been clinically evaluated and proven to be useful so far. Based on our experience, detection systems for fragmented red cells (FRC), immature platelets (immature platelet function, IPF), and hematopoietic progenitor cells (HPC) are useful for the diagnosis of thrombotic microangiopathy, differential diagnosis of thrombocytopenia, and decision regarding the optimal timing to collect peripheral stem cells, respectively. Moreover, IPF were suggested to be an indicator of the platelet transfusion requirement. The establishment of non invasive assaying technology has been eagerly anticipated. We evaluated a hemoglobin measurement tool, and revealed that it might be applicable in predeposited, autologous blood donation. Some adverse transfusion reactions are related to neutrophil activation. Thus, we investigated the effects of serum from patients and blood donors, in the context of adverse reactions, on adhesion molecule expressions of neutrophils from volunteers using flow-cytometry. This kind of simple technology is expected to be useful in future studies to clarify the mechanisms and prevent adverse reactions.