Functional defects in phagocytic cells from patients with iron overload

Abstract

SummaryPhagocytic functions were studied in patients with iron overload. Phagocytosis of radiolabelled opsonised Staphylococcus aureus by mononuclear (MN) leucocytes and polymorphonuclear (PMN) leucocytes was measured in 15 and 16 patients, respectively. The intracellular killing capacity of MN and PMN leucocytes of seven and nine patients, respectively, and chemotaxis of PMN leucocytes of eight patients, were assessed also. These cellular functions were compared with phagocytic functions of controls tested on the same day, and with the normal ranges of phagocytic cell functions obtained with MN and PMN leucocytes from 48 and 59 healthy donors, respectively. One or more phagocytic functions were impaired in 62'5 per cent of the patients. Comparison of the various phagocytic functions in patients and simultaneously tested controls showed a significant decrease of the mean phagocytic capacity of the patients' MN and PMN leucocytes (P < o'oz5 and P < 0"o3, respectively), as well as the mean bactericidal activity of the NIN leucocytes (P < o'o5) and the mean chemotactic responsiveness of the PMN leucocytes (P < o'o~5). Patients with excess iron must be regarded as compromised hosts, not only because of the increased availability of iron for bacterial growth, but also because of the associated functional impairment of monocytes and granulocytes.

Mucormycosis in allogeneic bone marrow transplant recipients: report of five cases and review of the role of iron overload in the pathogenesis

“…Iron adversely affects the phagocytic, chemotactic and bactericidal capacity of neutrophils and monocytes and has been observed to inhibit the activity of natural killer cells and macrophages. 19,20 On the other hand, iron enhances the ability of microbes to grow in host cells, tissues and fluids. 21 However, in human plasma or on mucosal surfaces, the amount of free iron accessible for microbial invaders is very low.…”

Clinical Aspects of Iron Use in the Anemia of Kidney Disease

“…Iron overload results in a decrease in chemotaxis and phagocytosis of polymorphonuclear leukocytes (PMNL) (77). A marked decrease in intracellular killing of bacteria was noted in hemodialysis patients with a serum ferritin Ͼ650 g/L (78).…”

Signaling Role of Intracellular Iron in NF-κB Activation

“…First, iron is known to affect cellmediated immune response (14). Excessive iron load in macrophages reduces their functions, including phagocytosis, respiratory burst, and cytokine expression (15)(16)(17), the effects likely mediated by iron-mediated toxicity (18). On the other hand, at non-toxic concentrations, iron promotes macrophage differentiation (19) and functions, including anti-microbial effects (20) and TNF-mediated cytotoxicity (21).…”