IMMUNOHEMATOLOGY Impact of donor ABH-secretor status in ABO-mismatched living donor kidney transplantation Beatrice Drexler,1,2 Andreas Holbro,1,2 Joerg Sigle,3 Christoph Gassner,4 Beat M. Frey,4 Stefan Schaub,5 Patrizia Amico,5 Alexandra Plattner,1,2 Laura Infanti,1,2 Thomas Menter,6 Michael Jorg€ Mihatsch,6 Martin Stern,7 Andreas Buser,1,2 and Michael Dickenmann5 BO-mismatched living donor kidney transplan- BACKGROUND: The ABO blood group is a major tation is increasingly performed for patients determinant in living donor kidney transplantation since with end-stage kidney disease1 and was dem- AB antigens are expressed on renal tissue. Little onstrated to improve survival.2 Initial attempts attention has been directed to the ABH-secretor status of A of transplanting across the ABO blood group barrier were the donor kidney. As renal tissue is capable of secreting associated with high rates of early graft loss due to soluble ABH antigens in secretors, we examined the antibody-mediated rejection (AMR).3 In recent years, influence of the ABH-secretor status of kidney donors on progress in pretransplant antibody removal and immuno- outcome in ABO-mismatched living donor kidney suppression has markedly improved outcome after transplantation. ABO-mismatched living donor kidney transplantation4 STUDY DESIGN AND METHODS: We retrospectively analyzed all patients who underwent and therefore has become a standard procedure in many ABO-mismatched kidney transplantation at the University centers. Hospital Basel from September 2005 to October 2013. The ABH-secretor status was determined in all donors by molecular genetic analysis. RESULTS: Of all 55 patients who received transplants, ABBREVIATIONS: AMR 5 antibody-mediated rejection; we excluded all patients with donor-specific antibodies DSA 5 donor-specific anti-HLA; FUT2 5a1,2-l- (n 5 4). Forty-one donors were secretors (78%) and 11 fucosyltransferase 2; GFR 5 glomerular filtration rate; IA 5 were nonsecretors (22%). Recipients of ABH-secretor immunoadsorption; IQR 5 interquartile range. donor organs showed a significantly higher glomerular From the 1Department of Haematology, University Hospital filtration rate throughout the first 6 months Basel; and the 2Blood Transfusion Centre, Swiss Red Cross, posttransplant, whereas no significant influence on Basel, Switzerland; the 3Blood Transfusion Centre, Swiss Red posttransplant anti-A/B titers was found. Regression Cross, Aarau, Switzerland; the 4Blood Transfusion Service, analysis revealed a significant impact on humoral Swiss Red Cross, Zurich, Switzerland; and the 5Clinic for rejection, whereas not on vascular or interstitial rejection Transplant Immunology and Nephrology, the 6Institute for in protocol kidney biopsies. Pathology, and the 7Immunotherapy Laboratory, Department of CONCLUSION: The donor ABH-secretor status may Biomedicine, University Hospital Basel, Basel, Switzerland. have an influence on early posttransplant renal function Address correspondence to: Beatrice Drexler, University in patients undergoing ABO-mismatched living donor Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland; kidney transplantation. Further prospective studies with e-mail: [email protected]. long-term follow-up are needed to elucidate involved AB and MD shared last authorship. pathomechanisms. The study was supported by a research grant from the regional Blood Transfusion Center Basel, Swiss Red Cross, Switzerland. Received for publication August 14, 2015; revision received March 22, 2016; and accepted April 25, 2016. doi:10.1111/trf.13711 VC 2016 AABB TRANSFUSION 2016;56;2355–2361 Volume 56, September 2016 TRANSFUSION 2355 DREXLER ET AL. However, the mechanisms of transplant accommoda- (PCR) using sequence-specific priming technology in two tion and the early immunologic response in ABO- independent reactions. Heterozygous individuals would mismatched kidney transplantation is poorly understood so give positive amplification in both reactions, homozygous far. After pretransplant antibody removal by immunoad- individuals in one reaction only. Primers for the wild-type sorption and immunosuppressive treatment, isoagglutinin allele (428G) were FUT2-all1523R (CCGGCTCCCGTTCA titers tend to stay low in the posttransplant period.5 How- CCTG-30) and FUT2-Se1428G-F (CCGGCTACCCCTGCTC ever, the exact mechanisms for this phenomenon remains GTG-30), and FUT2-all1523R and FUT-se1428A-F (ACC unknown and little attention has been directed to the ABH- GGCTACCCCTGCTCGTA-30) for the mutant allele (428A), secretor status of the donor kidney. The term ABH secretor respectively. Concentrations of the primers in the final refers to the ability to secrete soluble ABH blood group sub- reaction volume were 200 nmol/L, those of the control 6 stances into body fluids, such as plasma or saliva. For primers (GH1 1 96-F, TGCCTTCCCAACCATTCCCTTA-30; example, group A secretors will secrete A substance. ABH and GH1 1 274-R, CCACTCACGGATTTCTGTTGTGTTTC-30, secretion is controlled by two inherited alleles (Se and se), resulting in a 434-bp PCR product) 90 nmol/L. All primers where Se is dominant and se is recessive. Approximately were provided by an oligonucleotide synthesizing service 80% of individuals are secretors (SeSe or Sese). The secretor (Microsynth). Beside primers, the final PCR–sequence- gene (Se) encodes for the enzyme a1,2-L-fucosyltransferase specific priming reaction composition and cycling parame- 2 (FUT2) that converts the H-precursor substance in tissues ters were as described previously for KEL*01/KEL*02 to H-substance, which can be further converted to A- and/ genotyping.11 or B-substance according to the individual’s personal blood group.7 Interestingly, renal tissue is also able to secrete solu- ble A and B blood group substance according to their ABH- Patient preparation and desensitization protocol secretor status.8-10 In consequence, we hypothesized that All patients were prepared and desensitized as previously the secretion of ABH antigens by donor kidneys is capable described.12 In short, basic immunosuppressive therapy of neutralizing circulating anti-A and/or anti-B of the recipi- including tacrolimus (0.1 mg/kg body weight twice daily), ent in vivo and therefore contributes to the transplant mycophenolate mofetil (1000 mg twice daily, 500 mg twice accommodation after ABO-mismatched kidney transplan- dailyifbodyweightwas< 50 kg), and prednisone (30 mg tation. In this respect, the objective of this study was to once daily) was started 2 weeks before transplantation. A investigate the influence of thedonorABH-secretorstatus single dose of rituximab (375 mg/m2) was given 4 weeks on outcome in ABO-mismatched living donor kidney before transplantation in an outpatient setting. Selective transplantation. blood group antibody removal by immunoadsorption (IA) was performed pretransplant with a low-molecular carbo- MATERIALS AND METHODS hydrate column containing A and/or B blood group anti- gens linked to a Sepharose matrix (Glycosorb, Glycorex Study design and population Transplantation). IA was performed daily until the isoagglu- We retrospectively analyzed all patients who underwent tinin titers were 8 or less. The transplantation was then car- major ABO-mismatched kidney transplantation at the ried out the following day. If one of the two titers University Hospital Basel from September 2005 to October remained higher than 8, additional IA was mandatory until 2013. Patients with donor-specific anti-HLA (DSA) were the target titer was achieved. With each session, two excluded. Patient, donor, and transplant characteristics plasma volumes, calculated with the formula of Kaplan13 were collected by chart review and through the electronic were processed. Additional 20 mg of intravenous (IV) basi- database of our institution. Donor-recipient pairs were liximab was administered on Days 0 and 4. Target tacroli- classified according to the ABH-secretor status of the mus trough levels were 10 to 12 ng/mL from Day 214 until donor. The study was approved by the local ethics Day 31, 8 to 10 ng/mL from Day 32 to Day 90, and 6 to 8 committee. ng/mL from Day 91 to Day 365 and 4 to 6 ng/mL there- after. Target mycophenolate mofetil trough level was more Molecular genetic analysis of secretor status than 2 mg/mL. Steroids (IV methylprednisolone and Pretransplant venous blood samples from the kidney prednisone orally) were tapered (500 mg IV on Day 0, donors were collected in tubes containing EDTA. Periph- 250 mg IV on Day 1, 100 mg IV on Day 2, 50 mg from eral blood mononuclear cells were isolated with the Day 3 to Day 6, and 0.5 mg/kg body weight from Day 7 Ficoll-Paque method. Samples were frozen at 2808Cfor with a reduction by 5 mg every 2 weeks until 15 mg/day later analysis. Genomic DNA was isolated with the use of andthenby2.5mgevery2weeksuntilamaintenance a DNA isolation kit (MagnaPure LC, Roche Diagnostics). dose of 0.1 mg/kg body weight). All complications of Wild-type (Se, 428G) and mutant (se, 428A) alleles of pretransplant preparation were prospectively recorded FUT2 gene were detected by polymerase chain reaction at each clinical visit. 2356 TRANSFUSION Volume 56, September 2016 ABH-SECRETOR IN KIDNEY TRANSPLANTATION Isoagglutinin titers test. A multivariate regression analysis was generated to Serologic blood group typing and antibody screening was evaluate the impact of recipient sex, blood group, initial performed by gel test (Gel Test ID-system, Bio-Rad Labo- titer, plasma transfusion, and secretor status on the risk of ratories DiaMed GmbH). The isoagglutinin