ABO-incompatible kidney transplantation using regenerative selective immunoglobulin adsorption

Immunoadsorption Column Reuse

Introduction:

Selective immunoadsorption (IA) is a technique to remove preformed Anti-ABO antibodies in ABO-incompatible renal transplants (ABOiRT). Since the cost of a single IA column is high and single use rarely achieves the target anti-ABO titers, its use is not widely spread. We studied the safety and efficacy of the reuse of IA columns in ABOiRT.

Methods:

Single-center, retrospective analysis of all patients who underwent ABOiRT with IA column reuse from January 2016 to July 2018. The column was reused after sterilization with ethylene oxide and flushed with normal saline before use. Target titers (IgG) were 1:4 preoperatively. Baseline IgG titers, plasma volume processed in each session, postoperative titer rebound were recorded. The primary outcome was IgG titer reduction after each use and adverse reaction during the IA column reuse. Patients were followed up until 1 year.

Results:

16 patients underwent ABOiRT using IA columns. Baseline IgG titer ranged from 1:32 to 1:512. Reuse of IA column was done 23 times and underwent 2^nd reuse for 9 times. The average plasma volume treated was 22 L. Efficacy of the IA column in log titer reduction of anti-ABO titer was 4 logs after the first use, 3 logs after 1^st reuse, and 1.5 logs after 2^nd reuse. 12 (75%) patients successfully reached the target IgG titer of ≤1:4 solely with column reuse. One patient received a single session of plasma exchange before transplantation. Postoperatively, one patient received one session of plasma exchange due to a rebound in anti-ABO antibodies. No serious side effects were noted during the reuse.

Conclusion:

IA column reuse up to two times showed efficacy in the successful reduction of antibody titers. Column reuse was not associated with any significant side effects.

Therapeutic apheresis in kidney transplantation: An updated review

Therapeutic apheresis is a cornerstone of therapy for several conditions in transplantation medicine and is available in different technical variants. In the setting of kidney transplantation, immunological barriers such as ABO blood group incompatibility and preformed donor-specific antibodies can complicate the outcome of deceased- or living- donor transplantation. Postoperatively, additional problems such as antibody-mediated rejection and a recurrence of primary focal segmental glomerulosclerosis can limit therapeutic success and decrease graft survival. Therapeutic apheresis techniques find application in these issues by separating and selectively removing exchanging or modifying pathogenic material from the patient by an extracorporeal aphaeresis system. The purpose of this review is to describe the available techniques of therapeutic aphaeresis with their specific advantages and disadvantages and examine the evidence supporting the application of therapeutic aphaeresis as an adjunctive therapeutic option to immunosuppressive agents in protocols before and after kidney transplantation.

Strategies to overcome the ABO barrier in kidney transplantation

Kidney transplantation across the ABO blood group barrier was long considered a contraindication for transplantation, but in an effort to increase donor pools, specific regimens for ABO-incompatible (ABOi) transplantation have been developed. These regimens are now widely used as an integral part of the available treatment options. Various desensitization protocols, commonly based on transient depletion of preformed anti-A and/or anti-B antibodies and modulation of B-cell immunity, enable excellent transplant outcomes, even in the long-term. Nevertheless, the molecular mechanisms behind transplant acceptance facilitated by a short course of anti-humoral treatment are still incompletely understood. With the evolution of efficient clinical programmes, tailoring of recipient preconditioning based on individual donor-recipient blood type combinations and the levels of pretransplant anti-A/B antibodies has become possible. In the context of low antibody titres and/or donor A2 phenotype, immunomodulation and/or apheresis might be dispensable. A concern still exists, however, that ABOi kidney transplantation is associated with an increased risk of surgical and infectious complications, partly owing to the effects of extracorporeal treatment and intensified immunosuppression. Nevertheless, a continuous improvement in desensitization strategies, with the aim of minimizing the immunosuppressive burden, might pave the way to clinical outcomes that are comparable to those achieved in ABO-compatible transplantation.

The First Fifty ABO Blood Group Incompatible Kidney Transplantations: The Rotterdam Experience

This study describes the single center experience and long-term results of ABOi kidney transplantation using a pretransplantation protocol involving immunoadsorption combined with rituximab, intravenous immunoglobulins, and triple immune suppression. Fifty patients received an ABOi kidney transplant in the period from 2006 to 2012 with a follow-up of at least one year. Eleven antibody mediated rejections were noted of which 5 were mixed antibody and cellular mediated rejections. Nine cellular mediated rejections were recorded. Two grafts were lost due to rejection in the first year. One-year graft survival of the ABOi grafts was comparable to 100 matched ABO compatible renal grafts, 96% versus 99%. At 5-year follow-up, the graft survival was 90% in the ABOi versus 97% in the control group. Posttransplantation immunoadsorption was not an essential part of the protocol and no association was found between antibody titers and subsequent graft rejection. Steroids could be withdrawn safely 3 months after transplantation. Adverse events specifically related to the ABOi protocol were not observed. The currently used ABOi protocol shows good short and midterm results despite a high rate of antibody mediated rejections in the first years after the start of the program.

The selective therapeutic apheresis procedures

Selective apheresis procedures have been developed to target specific molecules, antibodies, or cellular elements in a variety of diseases. The advantage of the selective apheresis procedures over conventional therapeutic plasmapheresis is preservation of other essential plasma components such as albumin, immunoglobulins, and clotting factors. These procedures are more commonly employed in Europe and Japan, and few are available in the USA. Apheresis procedures discussed in this review include the various technologies available for low-density lipoprotein (LDL) apheresis, double filtration plasmapheresis (DFPP), cryofiltration, immunoadsorption procedures, adsorption resins that process plasma, extracorporeal photopheresis, and leukocyte apheresis.

ABO-incompatible kidney transplantation

PURPOSE OF REVIEW

A dramatic shortage of available organs around the world encouraged attempts to cross previously forbidden immunological boundaries in kidney transplantation. This review focuses on the recent results of ABO-incompatible kidney transplantation.

RECENT FINDINGS

The outcome of ABO-incompatible kidney transplantation in terms of patient and graft survival is comparable to ABO-compatible transplantation for adult and pediatric recipients. Splenectomy has been replaced by the B-cell-depleting agent rituximab to avoid isoagglutinin titer rebound, prevent antibody-mediated rejection, and improve graft survival. However, the risk for infections may be increased and warrants caution. Corticosteroids remain a necessary component of any ABO-incompatible protocol; early as well as late steroid withdrawal may bear an enhanced risk for acute rejection and should only be performed with careful follow-up including protocol biopsies. The few studies that have long-term outcomes using protocol biopsies have characterized a state of accommodation by up-regulation of complement inhibitors, down-regulation of A/B antigens, and establishment of endothelial chimerism over time.

SUMMARY

The experience accumulated around the world indicates that ABO-incompatible kidney transplantation is well tolerated and effective in adults and in children, and it represents an important step forward in expanding the living donor pool. Further understanding of ABO-incompatible graft accommodation may have broader implication also for human leukocyte antigen-sensitized allograft recipients.