NEUTROPHILS FROM PATIENTS WITH SECONDARY HEMOSIDEROSIS CONTAIN EXCESSIVE AMOUNTS OF AUTOTOXIC IRON

Secondary haemosiderosis may be accompanied by a decrease in the phago cytic function of neutrophils (PMNs). This dysfunction has been attrib uted to an exaggerated generation of oxidants induced by intracellular iron. However, an accumulation of iron has so far not been reliably d emonstrated in neutrophils harvested from iron-overloaded patients. Si x polytransfused haemodialysed patients, with a serum ferritin level h igher than 1000 mug/l, and 10 healthy controls were investigated. The iron status of PMNs was evaluated by iron determination using atomic a bsorption spectrometry and by ferritin measurement using radioimmunoas say. The phagocytic performance was measured by cytofluorometry. The r esults confirm that PMNs from the haemosiderosis patients have a decre ased 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 hae mosiderosis than in healthy controls. This iron accumulation may be to xic for the PMNs and may, at least partially, explain the three-fold h igher risk of bacteraemia which has been reported in those patients.