Biomarkers in renal transplantation

Purpose of review An important effort is being made among the transplant community investigating novel biological markers at different biological levels that enable transplant clinicians to identify patients at risk for allograft rejection or, conversely, patients in whom immunosuppression could be safely minimized. Here, we review recent important biomarkers that have shown relevant impact on renal graft outcome. Recent findings Important collaborative studies have allowed the identification of biomarkers or biological signatures indicative of organ tolerance or rejection in different transplant settings (mainly kidney and liver transplantation). This has required novel and highly specific technological assays focused at different biological levels, employing peripheral blood, urine and grafts tissue. Noteworthy, standardization and methodical validation of reliable tests or biomarkers is being a crucial task since the start of this challenge. These endeavours include detailed characterizations of serum alloantibody levels, measurements of individual soluble or cell-surface markers in peripheral blood, urine or both; profiling gene expression, proteome expression patterns or both and evaluations of peripheral cellular alloimmunity, among others. Summary Despite the important advances achieved so far in the identification of several potentially useful biomarkers of tolerance, rejection or both, validation and demonstration of their clinical utility still needs to be tested. Ultimately, in order to facilitate the achievement of such important goal, all efforts should probably be performed in the context of international cooperative networks.