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Impairment of phagocyte oxidative metabolism in hemodialyzed patients with iron overload
Abstract:
In order to study the influence of iron overload on the polymorphonuclear leucocyte (PMN) metabolism of patients on chronic hemodialysis, generation of superoxide anion (O2-) by PMN in whole blood was compared in two groups of hemodialyzed patients: group A consisted of twenty-one individuals with serum ferritin levels above 1000 ng/ml and group B of nineteen individuals with serum ferritin levels below 1000 ng/ml. Whereas basal production of O2- was similar in the two groups (6.3 +/- 4.6 vs 11.5 +/- 8.3 nmoles O2- 10(6) granulocytes-1 15 min-1) (mean +/- s.e.m.), PMN response to opsonized zymosan was significantly lower in group A as compared with group B (86.5 +/- 6.3 vs 120.4 +/- 8.2 nmoles O2- 10(6) granulocytes-1 15 min-1) (p less than 0.01). Superoxide anion generation induced by the dialysis procedure was reduced in eight patients from group A (89.2 +/- 32.1) as compared with eight patients from group B (374.3 +/- 100.0 nmoles O2- 10(6) granulocytes-1 15 min-1) (p less than 0.05). These data suggest that iron overload may be involved in the impairment of neutrophil phagocytosis in patients on chronic hemodialysis.
Insights
Iron overload in hemodialysis patients impairs neutrophil function. Superoxide anion generation by polymorphonuclear leucocytes (PMNs) was significantly reduced in patients with high ferritin levels, suggesting impaired phagocytosis.
Area of Science:
- Nephrology
- Immunology
- Hematology
Background:
- Chronic hemodialysis patients often experience iron overload.
- Iron overload's impact on immune cell function, particularly neutrophils, is not fully understood.
- Polymorphonuclear leucocytes (PMNs) play a crucial role in host defense through phagocytosis.
Purpose of the Study:
- To investigate the influence of iron overload on polymorphonuclear leucocyte (PMN) metabolism in patients undergoing chronic hemodialysis.
- To compare superoxide anion generation by PMNs in patients with high versus low serum ferritin levels.
Main Methods:
- Compared superoxide anion (O2-) generation in whole blood PMNs from two groups of hemodialyzed patients: Group A (ferritin > 1000 ng/ml) and Group B (ferritin < 1000 ng/ml).
- Assessed basal O2- production and PMN response to opsonized zymosan.
- Measured O2- generation induced by the dialysis procedure itself.
Main Results:
- Basal O2- production was similar between groups.
- PMN response to opsonized zymosan was significantly lower in Group A compared to Group B (p < 0.01).
- Dialysis-induced O2- generation was significantly reduced in Group A patients compared to Group B patients (p < 0.05).
Conclusions:
- Iron overload in hemodialysis patients is associated with impaired neutrophil function.
- Reduced superoxide anion generation suggests that iron overload may contribute to compromised neutrophil phagocytosis in this population.