Plasma and urine leukocyte elastase-alpha1protease inhibitor complex as a marker of early and long-term kidney graft function.

Background: Neutrophils are mediators of ischaemia/reperfusion (I/R) injury following kidney transplantation (kTx). Leukocyte elastase (LE) complex with alpha(1)protease inhibitor (LE-alpha(1)PI) is a marker of neutrophil degranulation. The aim of this study was to evaluate LE-alpha(1)PI as a marker of I/R kidney damage and to search for correlations between leukocyte activation and post-transplant complications.

Methods: Plasma and urine LE-alpha(1)PI were estimated in 55 deceased-donor kidney graft recipients on postoperative days (POD) 1, 3 and 7, as well as in the late post-transplant period.

Results: The plasma LE-alpha(1)PI level peaked on POD 1 after kTx, and the urine LE-alpha(1)PI peaked on POD 3. On POD 1 and POD 3, the urine LE-alpha(1)PI levels were higher in delayed graft function (DGF) patients than in patients with immediate graft function (IGF: P < 0.001 and P < 0.003, respectively). Urine LE-alpha(1)PI excretion on POD 1 was significantly higher in patients with longer cold ischaemia time (CIT) than in patients with shorter CIT, P < 0.002. Multivariate regression model revealed two factors influencing the occurrence of early acute rejection-urine LE-alpha(1)PI complex on POD 3 and human leukocyte antigen (HLA) mismatches. There was a significant association between the plasma LE-alpha(1)PI on POD 3 and serum creatinine level 6 and 12 months after kTx (r(2) 0.24; P < 0.005 and 0.19; P < 0.005, respectively).

Conclusions: This study is the first presentation of a simple, non-invasive measurement of neutrophil activation after kTx. It also demonstrates a strong correlation between the early post-transplant LE-alpha(1)PI complex level and kidney graft function.