Since 1991, the international Banff Classification has been revisited every 2 years to integrate advances in clinical research into best-treatment practices for organ transplantation. At the 2017 Banff conference, 479 delegates from 23 countries reviewed two seminal concerns in the kidney-transplant field: how T cell-mediated rejection is related to inflammation in areas of interstitial fibrosis and tubular atrophy, and the evolution of molecular diagnostics, particularly for identifying antibody-mediated rejection. These discussions prompted significant updates to the Banff scheme.
The relationship between i-IFTA severity and graft survival has been well established. Despite this, i-IFTA has previously been excluded as a diagnostic criterion of TCMR. Recent findings, however, suggest that inflammation in IFTA can be a manifestation of chronic active TCMR, particularly when other features of T cell-mediated alloimmunity, such as tubulitis, are present. A sequential relationship between early acute TCMR and later chronic active TCMR with i-IFTA has also been reported. Based on these findings, the Banff classification has been updated to include scoring of i-IFTA for diagnosing chronic active TCMR, after exclusion of other causes for IFTA inflammation.
ABMR diagnostic criteria were also revised. Positive DSA results aren’t always available for ABMR, creating a need for alternative markers of antibody-mediated graft rejection. Two such markers – C4d and genes associated with antibody-mediated tissue injury – have shown promise in filling in this gap. Both C4d staining and molecular ABMR correlates are potential diagnostic tools. Because each can significantly improve the accuracy of ABMR diagnosis, both markers have now been incorporated into the Banff classification as surrogates for DSA.
The final two updates of note include removal of the term “acute” from acute/active ABMR to help distinguish among the many forms of active ABMR and new guidelines for when renal allograft biopsies should be sampled for molecular diagnostics.
The changes and recommendations made at the 2017 conference are expected to stimulate further study of the new Banff criteria for graft rejection. By improving the risk stratification of patient outcomes and enhancing the design of next-generation clinical trials aimed at treating ABMR and chronic active TCMR, the new criteria may just elevate the current standard of care in organ transplantation to a new level.