Dysfunction of polymorphonuclear leukocytes in uremia

There is increased incidence of infectious complications in uremic patients, indicating impairment of cellular host defense in these patients. Several reports confirm metabolic and functional abnormalities of polymorphonuclear leukocytes (PMNL) including altered adherence to endothelial cells, altered generation of reactive oxygen species, altered release of microbial enzymes, impaired chemotaxis, phagocytosis, intracellular killing of bacteria, altered carbohydrate metabolism, and/or impaired ATP formation. Several studies report on correlations between PMNL dysfunction, especially phagocytosis and oxidative burst, and ferritin content. Deferoxamine therapy improved PMNL function. Chronic renal failure is a state of increased cytosolic calcium. Increased cytosolic calcium is associated with several alterations of PMNL function and metabolism, which improve by normalization of cytosolic calcium either by calcium channel blockers or by lowering of elevated parathyroid hormone. Each hemodialysis session using bioincompatible membranes triggers neutrophil activation, evidenced by overexpression of adhesion molecules, elevation of cytosolic calcium, release of PMNL granular enzymes, and generation of reactive oxygen species. Several studies claim that this results in chronic downregulation of phagocyte function. Several granulocyte inhibitory compounds have been isolated and characterized from uremic serum. The uremic retention product p-cresol depresses respiratory burst activity. The following granulocyte inhibitory peptides could be isolated from dialysis patients: granulocyte inhibitory protein I and II with homology to light chain proteins and beta 2-microglobulin, degranulation inhibitory protein I and II being identical to angiogenin and complement factor D, and immunoglobulin light chains. These proteins inhibit PMNL function in nanomolar concentrations.