Neutrophils from patients with secondary haemosiderosis contain excessive amounts of autotoxic iron.

Secondary haemosiderosis may be accompanied by a decrease in the phagocytic function of neutrophils (PMNs). This dysfunction has been attributed to an exaggerated generation of oxidants induced by intracellular iron. However, an accumulation of iron has so far not been reliably demonstrated in neutrophils harvested from iron-overloaded patients. Six polytransfused haemodialysed patients, with a serum ferritin level higher than 1000 micrograms/l, and 10 healthy controls were investigated. The iron status of PMNs was evaluated by iron determination using atomic absorption spectrometry and by ferritin measurement using radioimmunoassay. The phagocytic performance was measured by cytofluorometry. The results confirm that PMNs from the haemosiderosis patients have a decreased phagocytosis. Moreover, they demonstrate for the first time that these PMNs have an increased cellular iron and ferritin content. Both latter concentrations were 4 to 5 times more elevated in secondary haemosiderosis than in healthy controls. This iron accumulation may be toxic for the PMNs and may, at least partially, explain the three-fold higher risk of bacteraemia which has been reported in those patients.