Noninvasive methods to assess the risk of kidney transplant rejection

In current clinical practice, immune reactivity of kidney transplant recipients is estimated by monitoring the levels of immunosuppressive drugs, and by functional and/or histological evaluation of the allograft. The availability of assays that could directly quantify the extent of the recipient's immune response towards the allograft would help clinicians to customize the prescription of immunosuppressive drugs to individual patients. Importantly, these assays might provide a more in-depth understanding of the complex mechanisms of acute rejection, chronic injury, and tolerance in organ transplantation, allowing the design of new and potentially more effective strategies for the minimization of immunosuppression, or even for the induction of immunological tolerance. The purpose of this review is to summarize results from recent studies in this field.