Table 3.

Pros and cons of biomarkers of allogeneic kidney transplant rejection from a clinical perspective.

Biomarkers	Pros	Cons
NGAL	Correlation between high uNGAL concentration and elevated albumin/creatinine ratio [21] Measurement of cumulative NGAL concentrations 1 month after transplantation may predict a weak GFR after 2 years of follow-up [22] uNGAL distinguishes acute allograft rejection from other causes of AKI [24] Serum NGAL may be a predictor of renal rejection if detected as early as 1 day after transplantation [20] An appropriate cutoff value for serum NGAL can distinguish patients with AR from patients with other causes of acute allograft function [27]	In the first hour after transplant surgery, as a result of a large amount of urine excretion, uNGAL levels may be underestimated due to dilution of the urine [23] Induction of NGAL by certain drugs such as cephalosporin, cisplatin, and bisphosphonate [26]
KIM-1	High levels of KIM-1 in serum and urine are inversely related to GFR levels [28] High urinary KIM-1 excretion is a predictor of graft loss, independent of donor age, creatinine clearance, and proteinuria [40]	Renoprotective interventions in kidney injury can inhibit KIM-1 expression [40]
CXCL-10	CXCL-10 levels are significantly higher in individuals with T cell-mediated rejection compared to individuals with antibody-mediated rejection [10, 29] Mean CXCL-10 levels after kidney transplantation may be a predictor of impaired graft function even in the absence of acute rejection [41] CXCL-10 is a more sensitive and predictive parameter than serum creatinine in terms of monitoring response to antirejection therapy [42]	CXCL-10 concentration is not useful for determining DGF [29]
CysC	Serum cystatin C in case of GFR loss is a better marker than creatinine [45] Cystatin C has a significantly higher sensitivity than serum creatinine in its ability to detect a decrease in GFR < 60 ml/min in renal transplant recipients [45]	The strength of the correlation of cystatin C with renal rejection is strongly dependent on the timing of CysC determination after transplantation [30]
OPN	Plasma OPN levels were positively correlated with the severity of biopsy-proven acute cellular rejection [31]	OPN is probably a nonsignificant regulator of apoptosis in acute rejection [48]
CLU	CLU in plasma may be a significant biomarker of DGF as early as 4 hours after kidney transplantation [47]	The lack of rapid tests for clusterin hinders rapid clinical application, although rapid tests are available for many proteins, including NGAL and KIM-1 [47]