Effect of different dialyzers on defensins during hemodialysis

Abstract

Background. Defensins are antimicrobial peptides that constitute 30% to 50% of total azurophil granule proteins. Although the activation of azurophils during hemodialysis has been reported, including the release of granulocyte lactoferrin, myeloperoxidase, and elastase, the release of defensins during hemodialysis has not been investigated. The purpose of this study was to determine the effects of hemodialysis on defensin release. Methods. Plasma defensin levels and excreted defensins in dialyzer eluates and dialysates during hemodialysis were determined by radioimmunoassay. Thirty hemodialysis patients were divided into three groups, each group using a different dialyzer membrane: cuprophan (CU), polymethylmethacrylate (PMMA), or polysulfone (PS). Results. The postdialysis plasma defensin level in the CU group was significantly increased compared with the predialysis level. In contrast, defensin levels in the PMMA and PS groups showed significant decreases postdialysis. The predialysis neutrophil count and defensin level exhibited a significant positive correlation in all groups. However, postdialysis, a significant positive correlation was found only in the CU group. Interestingly, defensin excretion in the dialyzer eluates of the PMMA group and in the dialysates of the PS group was higher than that in each of the other two groups respectively. Conclusions. No significant statistical correlation between postdialysis neutrophil count and defensin level was observed in the PMMA and PS groups, a finding that may be explained by the increased excretion of defensins during hemodialysis in these groups. These results suggested that plasma defensin level may be a marker for granulocyte activation in patients dialyzed with membranes showing lower levels of excreted defensins. This study also revealed the importance of determining both plasma changes and excreted volumes of granule proteins to define neutrophil degranulation during hemodialysis.