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

Since Tydén's description of ABO-incompatible (ABOi) kidney transplantations based on antigen-specific immunoadsorption (IA) and rituximab (Tydén 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 IAs 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 IAs are performed every other day, instead of daily. Postoperatively we perform IAs only, if titers mandate us to do so (Wilpert et al., Nephrol Dial Transplant 2007;22:3048-3051). We report on 11 "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 high-titer 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.