Platelets and platelet-activating factor acetylhydrolase in septic patients

Introduction

Platelet-activating factor (PAF) and its inactivating enzyme PAF-acetyl-hydrolase (PAF-AH) are implicated in the development of sepsis and its sequela septic shock. It has been shown that the administration of r PAF-AH has a beneficial effect on the outcome of sepsis in animals as well as in humans.

Methods

We measured PAF-AH activity daily in 2586 plasma samples that were obtained from 240 patients admitted to our intensive care unit. Patients were screened daily for sepsis according to ACCP/SCCM criteria, and PAF-AH activities were analysed in relation to severity of sepsis and to whole blood platelet count as an indicator of platelet activation and consumption.

Results

PAF-AH activity was positively correlated to the severity of disease, but was proved to be a poor sepsis marker, when compared to others, such as neopterin, TNFα, procalcitonin etc. In patients with septic shock a low PAF-AH activity (<2.00 μmol/ml/h) could indicate a high mortality risk. Only 4 patients met these criteria, but all died. Platelet count was highest in patients with uncomplicated sepsis, but dropped dramatically in septic shock. The overall correlation between PAF-AH and platelet count was relatively poor (r = 0.266), but remarkable differences were observed between patients with PAF-AH activities <2.001 or >5.00) μmol/ml/h, resp.: 125 (70/112) × 10⁸/ml versus 280 (206/388) × 10⁸/ml; P < 0.00l.

Conclusion

Our data provide further evidence that PAF-AH has a beneficial effect in sepsis and that it can prevent platelet activation and sequestration which is known to contribute to multiple organ failure.

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