Neutrophil activation in acute renal failure and sepsis

Neutrophils, a type of white blood cell, can become activated during sepsis, widespread infection in the bloodstream. Neutrophils are also activated by C5a, a fragment released as part of activation of complement, a step in the immune response. C5a and related complement complexes are noted after regular hemodialysis treatment (RDT). RDT is a treatment for kidney failure in which the blood is removed from the body, filtered through a machine, and returned. C5a is found after RDT when the dialyzers are made of cuprophane (a kind of cellulose), but not when they are made of noncellulosic materials. It is therefore possible that neutrophils in dialysis patients with acute renal failure (ARF) and sepsis would become excessively activated, resulting in detrimental changes in white blood cell function. To study this, investigators took blood samples from 21 patients in ARF, 11 of whom had also developed sepsis, who underwent dialysis with dialyzers of both cuprophane and polysulfone (a noncellulosic material). Control values were obtained from patients with uremia (high blood levels of urea) who underwent RDT. Results showed that white blood cell counts fell in all three groups (ARF with sepsis, ARF without sepsis, and controls) during dialysis with cuprophane dialyzers, with much smaller drops after polysulfone dialysis. This indicated that granulocytes had moved into the small blood vessels in the lungs, a sign that their adherent properties had been altered. Patients undergoing RDT showed increased levels of most granulocyte-associated enzymes during dialysis with cuprophane, and patients with ARF without sepsis showed an even greater increase. Those with ARF and sepsis showed the greatest increase, however. All groups showed only mild elevations after dialysis with polysulfone dialyzers. Since excessive neutrophilic degranulation (activation) can lead to increased susceptibility to infection, the development of dialysis membranes that are more biocompatible may be indicated. (Consumer Summary produced by Reliance Medical Information, Inc.)