What causes polymorphonuclear leukocytes

The role of polymorphonuclear neutrophils in the pathogenesis of acute lung failure (ARDS)

Summary

The physiological tasks of the polymorphonuclear neutrophil leukocytes (PMNL) include the elimination of invaded microorganisms in the context of defense against infection and the removal of non-vital tissue during wound healing. For this, PMNL are equipped with highly effective microbicidal mechanisms, the stimulation of which not only fulfills a protective function, but can also destroy the body's own tissue. Numerous animal experiments and clinical findings show that polymorphonuclear neutrophils damage the alveolo-capillary membrane and can contribute to the development of acute lung failure. The detection of activators of polymorphonuclear neutrophil leukocytes, the increase in their potentially cytotoxic functions, their increased pulmonary sequestration and the inverse relationship of these parameters to lung function in patients with ARDS suggest a causal role of polymorphonuclear neutrophil leukocytes in the pathogenesis of this syndrome. On the other hand, the manifestation of acute lung failure despite pre-existing leukopenia indicates the development of this clinical picture also through PMNL-independent mechanisms. Only on the basis of an exact analysis of the systemic inflammatory reaction, which is qualitatively and quantitatively different depending on the type and duration of the underlying disease, will it be possible to use anti-inflammatory drugs in a targeted manner without increasing the risk of infection in patients with trauma or sepsis.

Abstract

Polymorphonuclear leukocytes (PMNL) constitute the first line of defense in the protection of the host from invading microorganisms. PMNL also contribute to the removal of cellular debris from necrotic tissues during reparative processes. For these purposes PMNL are armed with highly efficient bactericidal mechanisms which, under certain pathophysiological conditions, can be turned against the host himself. A vast body of evidence indicates that PMNL are able to cause lung injury which may be followed by the development of acute respiratory distress syndrome (ARDS). Accordingly, in patients with ARDS blood concentrations of inflammatory activators of PMNL are elevated, cytotoxic mechanisms of PMNL are enhanced and sequestration of these cells has been demonstrated to be inversely proportional to gas exchange. The manifestation of ARDS in leukopenic patients, however, indicates the development of this clinical syndrome independently of the presence of PMNL. The ability to differentiate between PMNL-dependent and PMNL-independent pathways in the pathogenesis of this syndrome is not only of theoretical interest but also of therapeutic significance. Since the patient's systemic inflammatory response may vary according to the stage and type of the underlying disease, an exact qualitative and quantitative analysis of PMNL functions may provide the rationale for new anti-inflammatory drug regimens aimed at modifying the host's response without increasing the risk of infection.

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Affiliations

  1. Institute for Anaesthesiology, Großhadern Clinic, Ludwig Maximilians University Munich, DE

    M. Thiel, C. Zourelidis & K. Peter

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Thiel, M., Zourelidis, C. & Peter, K. The role of polymorphonuclear neutrophils in the pathogenesis of acute lung failure (ARDS). Anesthetist45, 113-130 (1996). https://doi.org/10.1007/s001010050246

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  • Key words Acute lung failure - neutrophils - pathomechanisms
  • Key words Adult respiratory distress syndrome - Neutrophils - Pathomechanisms