ABO-incompatible kidney transplantation-proposal of an intensified apheresis strategy for patients with high initial isoagglutinine titers.

Since Tyden's description of ABO-incompatible (ABOi) kidney transplantations based on antigen-specific immunoadsorption (IA) and rituximab (Tyden et al., Am J Transplant 2005;5:145-148), this technique has been successfully adopted by many transplant centers worldwide. The majority of centers strictly adhere to the Swedish protocol and perform lAs with a target volume of 1.5-2 plasma volumes on preoperative days -6, -5, -2, and -1, and postoperative days +3, +6, and +9, respectively. Patients who initially present with an IgG anti-A/B titer higher than 1: 128 are not considered suitable candidates for ABOi transplantation by the Swedish protocol. Our center has gone beyond these suggestions and follows a slightly different strategy: We do not exclude patients with initial IgG anti-A/B titers higher than 1:128 and we perform as many preoperative antigen-specific extracorporeal treatments as needed to reach a threshold isoagglutinine titer of 1:4 or less. To intensify isoagglutinine clearance preoperatively, the total target volume per treatment was increased to 2.5-3 plasma volumes. Preconditioning lAs are performed every other day, instead of daily. Postoperatively we per-form lAs only, if titers mandate us to do so (Wilpert et al., Nephrol Dial Transplant 2007;22:3048-3051). We report on It "high-titer patients" who entered our ABOi kidney transplant program with initial titers of 1:256 or above. Seven of 11 patients (64%) could successfully be transplanted with our modified ABO-apheresis protocol. Four of 11 hightiter patients did not reach target isoagglutinine titers of 1:4 or less and therefore did not undergo transplantation. We conclude that intensified preoperative IA renders a majority of high-titer patients suitable candidates for ABOi kidney transplantation.