The classification and treatment of antibody-mediated renal allograft injury: where do we stand?

Since the acceptance of the detection of C4d in allografts as a reliable tool to mark a humoral alloresponse, de novo antibody-induced graft injury has attracted much attention. Antibodies and B cells are the new frontier in transplantation. At this juncture carefully designed studies are critical in order to gain solid diagnostic, therapeutic, and prognostic knowledge about the role of antibodies in graft injury and to avoid any confusion and misconception. One prerequisite is the strict adherence to refined classification systems of renal transplant rejection that carefully split and categorize different phenotypes of humoral mediated graft damage and ideally also include information on anti-donor antibody specificity and titers. Sun and colleagues follow this concept and provide evidence that mixed cellular and antibody-mediated graft rejection can respond favorably to intensified immunosuppression with tacrolimus and mycophenolate mofetil. What will the future bring to treat rejection episodes with a dominant, co-dominant, or minor antibody response?