816 NEUTROPHIL FUNCTION IN TRANSFUSION-INDUCED IRON OVERLOAD

Abstract

Iron overload damages a wide variety of organ systems, and is accompanied by an increased susceptibility towards infections in some patients. The contribution of neutrophil (PMN) dysfunction to such infections has not been explored. We investigated PMN functions in seven chronically transfused children with documented iron overload (3 each with thalassemia major and sickle cell disease, and 1 with pure red cell aplasia). All patients had received monthly transfusions for over 6 years and had ferritin levels above 3000 ng/ml. A modification of Tan's technique was used to assay PMN bactericidal activity and phagocytosis towards Staphylococcus aureus 502 A. Results are reported in percent viable intracellular (IB) or extracellular (EB) bacteria after 30 or 120 minutes of incubation. PMN oxygen consumption (expressed as mM O2/109 PMNs) was measured by polarigraphy after stimulation with phorbol myristate acetate. All results (x ± SE) are indicated in the table below.PMN functions of iron overloaded patients appear to be normal. The abnormal propensity toward infections of such patients does not seem to be caused by a deterioration of their PMN phagocytic or bactericidal mechanisms.