Saudi Journal of Kidney Diseases and Transplantation

: 2020  |  Volume : 31  |  Issue : 3  |  Page : 572--581

ABO-incompatible transplantation without conventional induction immunosuppression (IL-2RB or depleting agents)

Benil Hafeeq1, Feroz Aziz1, Sajith Narayanan2, Ismail Naduvileparambi Aboobacker2, Jyotish Chalil Gopinathan1, Ranjit Narayanan3, Julie Jose Binu4, NA Uvais5,  
1 Department of Nephrology, Iqraa International Hospital and Research Center, Kozhikode, Kerala, India
2 Department of Nephrology, Aster MIMS Hospital, Kozhikode, Kerala, India
3 Department of Nephrology, Aster MIMS Hospital, Kottakkal, Kerala, India
4 Transfusion Medicine Department, Iqraa International Hospital and aResearch Center, Kozhikode, Kerala, India
5 Department of Psyhiatry, Iqraa International Hospital and Research Center, Kozhikode, Kerala, India

Correspondence Address:
Benil Hafeeq
Department of Nephrology, Iqraa International Hospital and Research Center, Kozhikode, Kerala


Transplantation across the ABO blood group (ABOI-Tx) has facilitated to increase in donor pool for living donor kidney transplantation. Increased risk of rejection despite augmented immunosuppression has been the concern for many transplant programs in initiating an ABOI-TX program. The benefits of induction immunosuppression on long-term graft survival in immunologically low-risk individuals are still not clear. Increased immunosuppression of ABOI-Tx recipients before transplantation could provide an opportunity to transplant without induction with IL2-R blockers or Lymphocyte depleting agents. The aim of our study is to analyze the outcome of our series of 25 consecutive ABOI-Tx patients who underwent transplantation without routine thymoglobulin or IL2R-blocker induction. Our study is a prospective observational study for the first 25 consecutive patients who had undergone ABOI-Tx from two tertiary care centers in Kerala, India, having the same IS protocol. Anti-A and anti-B titers ≤1:512 by Gel-method (Biorad) were accepted for desensitization. Patients underwent CDC-crossmatch, Flow-crossmatch, and Luminex-anti-HLA-antibody-screen. Desensitization regimen included- Rituximab 200 mg on Day-21, Triple IS Prednisolone 10 mg, mycophenolate mofetil 1000 mg, and Tacrolimus 0.06 mg/bodywt from Day-14 and Plasma-exchange (PLEX) 3-4 sessions from day -7 to attain titer of 1:8 before transplantation. Transplantation was done without induction IS. Twenty-five patients underwent ABOI-Tx from both centers. Twenty recipients were male. The average age was 34.5 ± 8 years with follow-up of 503 ± 120 days. Eight donors were spouse, 13 were parents and three siblings. The average age of the donor was 46.3 ± 10.5 years. Twenty-two patients have normal functioning transplant with creatinine 1.23 ± 0.2 mg/dL. Kaplan–Meier analysis showed patient survival of 91.2% and death censored graft survival of 95.6% at 36 months. Two patients were lost; one on the postoperative day (POD)-3 due to ACS and second on POD-22 due to sepsis. One graft loss occurred due to posttransplant HUS. Of the functioning 22 allograft-recipients, one had cellular rejection, which resolved with pulse steroids; one developed HUS due to CNI, which recovered with PLEX and switch to non-CNI based IS. One patient developed AMR on POD-4, which was completely reversed with PLEX, intravenous immunoglobulin (IVIG), and augmentation of IS. Three patients had CMV viremia and another three patients had BKV viremia, all resolved with treatment and tailoring of IS. Achieving acceptable anti-A/B titers prior to transplantation is the most critical step in ABOI-Tx. Avoidance of induction IS can reduce cost and infectious complications. Our data showed that there is no increased incidence of rejections in the first post-transplant year for immunologically low-risk individuals from histocompatibility standpoint undergoing ABOI-Tx without induction immunosuppression.

How to cite this article:
Hafeeq B, Aziz F, Narayanan S, Aboobacker IN, Gopinathan JC, Narayanan R, Binu JJ, Uvais N A. ABO-incompatible transplantation without conventional induction immunosuppression (IL-2RB or depleting agents).Saudi J Kidney Dis Transpl 2020;31:572-581

How to cite this URL:
Hafeeq B, Aziz F, Narayanan S, Aboobacker IN, Gopinathan JC, Narayanan R, Binu JJ, Uvais N A. ABO-incompatible transplantation without conventional induction immunosuppression (IL-2RB or depleting agents). Saudi J Kidney Dis Transpl [serial online] 2020 [cited 2020 Aug 14 ];31:572-581
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Full Text


ABO-incompatible transplantation has facilitated expansion of living donor pool with outcomes comparable to ABO compatible transplantation.[1] Incompatibility of blood group precludes transplantation in 30% of waitlisted patients.[2] Higher immunological risk, arduousness of executing immunomodulation with plasma exchange, variations in detecting ABO antibody titers, vulnerability to post-transplant infections and extra costs involved are hurdles that prevent this option being acceptable by the majority of transplant centers.[3]

Atop the conventional medications, patients are subjected to additional immunosuppression in the form of immunomodulation protocol which constitutes anti-B cell therapy, plasma exchange and predated maintenance immunosuppression. Different programs have modified the immunomodulation protocol with good short term results.[4] Attaining acceptable pre-transplant ABO antibody titers remains the most critical footing on which an ABOi transplant can be done. Jury is still out on the need of induction immunosuppression with thymoglobulin or IL2 receptor blocker for immunologically low-risk patients in the current era of immunosuppression with Tacrolimus and mycophenolate mofetil (MMF). ABOi transplantation incurs additional expenditure due to immunosuppression and prophylaxis, making this option a tough choice for a good proportion of centers. We report our series of 25 consecutive ABOi renal transplantations done without induction immunosuppression at two centers, which is covered by the same transplant service and with the same immunosuppression protocols.


Study design

The study is a prospective observational study of all living donor ABOi compatible transplantations done at two participating centers with the same nephrology service between June 2014 and January 2018. The prospective data were collected during patient visits in outpatient clinics. Crossmatch negative was taken as inclusion criteria. Crossmatches and antibody screens are done in the initial phase itself, and only low immunological risk is recruited for ABO-incompatible transplantation.

Histocompatibility testing protocols: Pre transplant immunological profiling was done to characterize patients as immunologically low-risk (LIR) before being accepted for ABOi transplantation program. Histocompatibility was done by two different algorithms in two time frames based on the availability of flow cytometer based crossmatch facility. Low immunological risk from June 2014 to October 2016: defined as anti-HLA antibody screen negative for class I and II by Luminex platform (Lab screen) and negative CDC crossmatch. From November 2016 onward, patients with negative Flow and CDC crossmatch without any donor-specific antibody by single-antigen bead analysis (Luminex platform) was identified as LIR.

Flow crossmatch description: Flow cytometer based crossmatch was done using BD FACSCalibur. The donor cells were incubated with recipients’ serum followed by the addition of a fluoresceinated (FITC) goat, anti-human polyclonal immunoglobulin reagent. In addition, a phycoerythrin labeled monoclonal antibody that detects B cells (CD19) and a peridinin chlorophyll protein (PerCP)-conjugated monoclonal antibody that detects T cells (CD3) are added. Results are then analyzed by flow cytometry and expressed as positive or negative based on a shift in median channel fluorescence intensity of the test serum with respect to the negative control. Out cutoff for flow-crossmatch positivity were 50 MCS for T cells and 100 MCS for B cells.

ABO titering methods and cutoffs

Isohaemagglutinin titers were done by the Column Agglutination method (CAT) using the Diamed Gel card (DiaMed GmbH, Cressier, Switzerland). The tests were done using erythrocytes from the general donor pool by combining 4–5 blood donor erythrocytes which was further subjected to standard Quality Control procedures in the lab before use. Baseline titer was done using such in-house prepared pooled erythrocytes as well as the renal donor erythrocytes, washed and suspended in low ionic strength saline. This was to rule out antigenic variants, especially seen in case of blood group A. If the difference in the titer between the two was greater than two dilutions, thereafter, all titers were done using the renal donor erythrocytes. All tests were done by the semi-automated method. Tube method was not preferred due to the high probability of variability dependent on operators and other factors.[5]

Immunomodulation protocol

The immunomodulation protocol [Figure 1] starts with injection rituximab 200 mg IV infusion single dose on day 21 before transplantation. Triple immunosuppression is started on Day-14; prednisolone 10 mg, MMF 1000 mg per day, and tacrolimus 0.06 mg/kg body wt. Tacrolimus dose is titrated to attain a level of 6–8 ng/dL. Plasma exchange is started in the week before transplantation as per the baseline titer. Single filter plasma exchange is given for titers ≤1:64 and double filtration PP using Evaflux (Kawasumi laboratories, Japan) as the second filter is given for titers >1:64. The number of plasmaphereses is titrated to attain a pre-transplant titer of 1≤16.{Figure 1}

Posttransplant immunosuppression

No induction immunosuppression was used in any patient. Steroids were given as Inj methylprednisolone 500 mg in on Day 0 followed by 250 mg on POD 1 and 2, subsequently tapered to oral prednisolone 5 mg by 4 postoperative months. Tacrolimus target level is aimed at 6–8 ng/dL in 1st postoperative month and subsequently 4–6 ng/dL. MMF aimed at 1500 mg in the first postoperative month followed by MMF 1000 mg per day.


Bactrim prophylaxis for six months, Valgan 450 mg OD for six months in CMV high risk, Valgan 450 mg OD for one month in intermediate risk individuals.


ABOi transplant program was started in June 2014. Twenty-five ABOi transplants have been done over two hospitals covered by same nephrology service between June 2014 and January 2018. Recipient characteristics are shown in [Table 1]. The mean age of recipients is 34.5 ± 8 years. Male gender constituted 80% of recipients. Five of 25 (20%) recipients had diabetic nephropathy as native kidney disease. All patients were on hemodialysis before transplantation, and mean dialysis vintage was 7.6 months. Parents constituted 52% of donors; three donors were siblings, of which two were HLA identical. The mean donor age was 46.3 ±10.5 years.

Histocompatibility characteristics are shown in [Table 2]. Only one patient was a retransplant candidate. Eleven patients had history of sensitization events either pregnancy, blood transfusion or prior transplantation. Six out of 11 sensitized patients were tested to have anti- HLA antibody positivity by luminex lab screen using mixed antigen beads. First 14 patients were identified as immunological low risk as they were negative by anti-HLA antibody screen and CDC crossmatch. Last eleven patients underwent flow crossmatch and was reported negative. After acquirement of flow crossmatch in 2015, flow crossmatch negativity and absence of any DSA by SAB analysis using the Luminex platform was identified as low immunologic risk (LIR).{Table 1}{Table 2}

As shown in [Table 3], 18 of 25 (72%) patients belonged to the O blood group and 16% had AB donors. No transplant was done from AB donor to O recipient. Seventeen of 25 (68%) patients had ABO antibody titer ≥ 1:64. DFPP was used in 52% of patients, mainly those with higher ABO antibody titers. The amount of FFP replacement was less in the DFPP group compared to those with single filter plasma exchange despite the DFPP group having higher titers (3.6 vs. 5.3 FFP per patient).{Table 3}


Two patients had acute rejection and both occurred in the first posttransplant week and both were wives donating to husbands. One was cellular rejection, which was treated with pulse steroids and other patient acute antibody-mediated rejection treated with plasmapheresis with IVIG. Both patients have normal graft function. The mean follow up of all patients was around 503 ± 320 days and mean creatinine was 1.23 ± 0.18 mg/dL [Table 4]. At 36 months posttransplant the patient survival was 91.2% and “Death Censored Graft Survival” was 95.6% [Figure 2].{Table 4}{Figure 2}

There were two patients loss in our cohort. The first patient had chronic glomerulo-nephritis as his native kidney disease. He was blood group O with wife with A group as donor. His initial anti-A titer was 1:32 which came down to 1:4 prior to transplantation after three sessions of plasma exchange. His anti-HLA antibody screen on the Luminex platform and CDC crossmatch were negative. He had coronary artery disease before transplantation with a history of NSTEMI, and CAG showed CTO not amenable to angioplasty. His transplant surgery was complicated with poor perfusion in the immediate postoperative period warranting redo transplant renal artery anastomoses. He had delayed graft function needing HD support. On 3rd POD he developed sudden onset chest pain and cardiac arrest during HD run from which he could not be revived.

Second patient whom we lost had ESRD due to diabetic nephropathy; was on HD for six months. Patient was O blood group with wife of blood group B as donor. The initial anti B titer was 1:128 and received five sessions of single filter plasma exchanges. His pretransplant anti-B titer was 1: 8. He had immediate graft function and attained creatinine of 1.2 on discharge on the 9th POD. Three weeks after transplantation he presented with low-grade fever and mental confusion. Evaluation showed right lower zone consolidation, and MRI revealed multiple foci of diffusion restriction in bilateral parietal, temporal and frontal lobes along with bilateral corona radiata suggestive of embolic infarcts. No organism could be isolated from the blood and urine. His graft function was normal and anti-B titers did not go up. His clinical course deteriorated over couple of days, developed respiratory failure with MODS and expired on POD 24.

One patient suffered graft loss due to post transplant HUS. He was blood group O with B positive wife as donor. His baseline anti-B titer was 1:32 and underwent transplantation with titer of 1:4, had a good immediate function. After 48 h he developed sudden onset abdominal discomfort and graft dysfunction. He was detected to have thrombocytopenia, schistocytes and elevated LDH. He had preserved urine output and normal perfusion on Doppler. He was initiated on plasma exchange immediately due to obvious clinical picture of HUS. Tacrolimus was discontinued, and steroids were hiked. Subsequently, urine output decreased and graft dysfunction ensued. Renal biopsy was suggestive of thrombotic microangiopathy (TMA). He was given thymoglobulin to cover for CNI withdrawal. Graft function could not be salvaged despite intensive plasma-exchange and supportive treatment. The patient is currently leading a productive life on hemodialysis.

Non-infectious complications

Post-transplant HUS was the most vexatious non-infectious complication that was encountered. Two patients developed post-transplant HUS. The first patient was the one mentioned above that resulted in graft loss. The second patient was O blood group with the father having A group as donor; had immediate graft function. On 3rd POD he developed graft dysfunction, thrombocytopenia, and features suggestive of hemolysis. PLEX was instituted; renal allograft biopsy showed features suggestive of TMA with tubules showing evidence of Tacrolimus toxicity [Figure 3]. CNI was held; it was maintained on prednisone and MMF. He responded to daily PLEX and graft function improved with resolution of HUS by 8th POD.{Figure 3}

Infectious complications

BKV screen of plasma and urine was done on all patients at the end of the 2nd postoperative month. Two patients had BK viruria alone and one had both viruria and viremia. All three resolved with curtailed immunosuppression. Three patients developed CMV viremia, one was in CMV high-risk individual and other two were in CMV intermediate-risk patients. Viremia resolved with holding MMF and treating with Valganciclovir. None had CMV disease. Two patients developed UTI following DJS removal; one of them had CAKUT as a native kidney disease. Both responded to culture-specific antibiotics. As previously mentioned, one patient was lost following sepsis following right lower lobe pneumonia [Table 5].{Table 5}


The evolution of ABOi transplantation has been stimulated by incessant attempts to develop protocols that are less complicated and more objective. Criteria for acceptable anti-A/B titers, methods of antibody quantification, methods of antibody removal, and immunosuppressive strategies have evolved over the last couple of decades.

Attaining acceptable pretransplant anti-A/B titers remains as one of the most critical steps for successful ABOi transplantation. Anti A/B titers <1:32 has been accepted as the cutoff by most of the centers.[6] Titers ≥1:64 has been associated with poor outcomes.[7] Patients with initial baseline titers less than 1:32 has been subjected to renal transplantation without any procedures for removal of antibody with good outcome.[4] Anti-A/B titers can be estimated by three methods – tube agglutination method, gel/bead centrifugation method and flow cytometer based assay in increasing order of reproducibility and consistency.[8],[9] Detection of both IgM and IgG antibodies are important. Tube agglutination method has shown significant inter-institutional variation in a national study done in Japan across >30 laboratories.[10] Gel/bead-based centrifugation method is becoming more utilized platform for anti-A/B titer assay and has less inter-laboratory variation compared to tube-agglutination method.[5] Pretransplant desensitization involves serial monitoring of titer based on which desensitization has to be tailored and hence each center has to have its own standardized protocol for estimating the anti-A/B titers. Extracorporeal removal of anti-A/B antibodies is done using plasmapheresis or adsorption columns.[11] Plasmapheresis can be done using a single or double filter, with technical advantage of the need of less replacement with the latter.[12] Adsorption using columns has been very effective. There have been no studies comparing the efficacy of each method, and each center has their own method of removal of antibodies, taking into consideration center’s expertise, cost, and baseline anti-A/B titers.

Although more and more transplant programs are becoming comfortable with ABOI transplantation, it is still considered an exercise of higher immunological risk. ABO system, unlike the HLA system, is less polymorphic but very antigenic. ABO antigens are poor inducers of T-cells.[13] Anti-A/B antibodies or isoagglutinins seen constitutively are of IgM subtype. Antibodies that are acquired during the life of an individual secondary to sensitizing events are of IgG subtype. Induction to produce IgG antibodies is a T-cell independent phenomenon. Both IgM and IgG antibodies can cause rejection, and it is believed that IgG is more important in causing immune injury. Tackling the B cells has also been the focus in immunomodulation for ABOi transplantation. After using cyclophosphamide for a brief period splenectomy had been the mainstay of B cell depletion for ABOi transplantation. Rituximab has replaced splenectomy, which had been cumbersome and a deterrent for doing ABOi transplantation for many programs. Dose of Rituximab has also been studied at different dosages, and the Japanese group has shown that a single dose of rituximab 200 mg produces effective B-cell depletion to facilitate ABOi transplantation with a good outcome.[14] In patients who have inherently low anti-A/B titer, ABOi transplantation had been done without B-cell depletion with good results.[4] Hopkins group had shown comparable five year outcome between their ABOi and ABO-compatible groups without giving B-cell depletion therapy and merely focusing on antibody removal and conventional IS.[15]

The role of induction immunosuppression in immunologically low-risk group constituting living related donors and non-sensitized recipients is still unclear. KDIGO guidelines on immunosuppression have mentioned the inevitability of individualizing induction protocol in immunologically low-risk group.[16] Most of the centers doing ABOi-Tx use an induction agent at the time of transplantation, commonly IL2- RB compared to thymoglobulin under the premise that ABOi transplantation has an increased immunological risk magnitude of which is uncertain.[17] Considering the anti-A/B isoagglutinin response is not driven by T cell mediation the role of induction is more unclear in otherwise immunologically low risk recipients.[13] The induction protocols varies between programs and is primarily based on immunological risk profile of the recipient. Protocol of our center was to proceed without induction IS for immunologically low risk patients and immunologically stratification primarily done based on anti-HLA antibody profiling using all the three platforms – CDC, Flow and Luminex. Consonant to most of the programs, patient undergoing ABOi transplantation in our center receive immunosuppression before transplantation in the form of at least four sessions of plasmapheresis, triple IS two weeks prior to transplant date and one dose of rituximab (200 mg) in pursuit of acceptable anti-A/B titers. Our perception has been that afore-mentioned immunosuppression provided a setting for avoiding induction in patients who were not of immunologically high risk from HLA-antibody standpoint. There is no data comparing different induction regimens in ABOi transplant like the one we have in a similar immunologically divergent scenario like transplantation in HIV-positive recipients.[18],[19]

Unlike anti-HLA antibodies pathogenicity of AB-antibodies are short-lived and is believed to undergo accommodation over a two week period. The time-limited antigenicity argues against the need of protracted immunosuppression. Many studies have shown an increased incidence of infections in ABOi transplant recipients. Increased incidence of BKVAN in ABOi transplants point toward the overall immunosuppressed state of the recipients presumably to the more intense immunosuppression they are subjected to.[20],[21] In a developing country with a high prevalence of infections like tuberculosis, adoption of any regimen with augmented immunosuppression should be taken with utmost caution. The cost of the induction agent estimates to about one-fourth to one-fifth of the whole transplant cost in a developing country. Obligatory need of prophylactic agents such as valgancyclovir in the setting of augmented IS adds to the cost, which may not be attractive in facilitating ABOi in developing world.


Breaking the less polymorphic ABO barrier has been a journey which has evolved with the advent of newer immunosuppressive agents, tools for better immunological profiling and quest for personalized immunosuppression. Developments in immunomodulation to attain acceptable anti-A/B titers have made the ABOi transplantation a widely acceptable modality. There is no evidence on ideal induction IS regimen for ABOi transplantation. Our study points toward the feasibility of doing ABOi transplantation in otherwise immunologically low-risk group with standard immuno-modulation protocol but without conventional induction IS of IL2-RB or thymoglobulin. As ABOi in being carried out by more centers there should be dedicated studies to understand the role of induction immunosuppression in ABOi transplantation.

Conflict of interest: None declared.


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