The Presence of Anti-HLA Antibodies before and after Allogeneic Hematopoietic Stem Cells Transplantation from HLA-Mismatched Unrelated Donors

Post-transplant de novo anti-HLA donor specific antibodies may contribute to poor graft function after haploidentical haematopoietic stem cell transplantation

De novo anti-HLA donor-specific antibodies (DSAs) were rarely reported in stem cell transplantation patients. We present a case of 39-year-old acute myelogenous leukaemia patient who developed de novo DSAs only 16 days after transplantation with the highest mean fluorescence intensity (MFI) of 7406.23, which were associated with poor graft function (PGF). We used plasma exchange (PE) and intravenous immunoglobulin (IVIg) to reduce DSA level. A series of treatment including mesenchymal stem cells and donor cell transfusion were used to help recover graft function. On day 130, the patient achieved a successful engraftment.

Successful Salvage Therapy by Second Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation in a Severe Aplastic Anemia Patient Presenting Donor-Specific Anti-HLA Antibodies After Graft Failure From Matched Sibling Donor HSCT: A Case Report and Review

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is potentially curative for severe aplastic anemia (SAA). Graft failure (GF) remains a life-threatening complication after HSCT. Preexisting anti-HLA antibodies, especially HLA-specific antibodies (DSA), have been demonstrated as a risk of GF.

CASE PRESENTATION

This report describes a woman with acquired SAA who presented with anti-HLA antibodies and GF. After the treatment of anti-HLA antibodies, engraftment was achieved through a second alternative donor HSCT. This work complied with the Declaration of Helsinki and the Declaration of Istanbul.

CONCLUSIONS

Based on our experience in treating this case, we hold that the presence of preoperative anti-HLA antibodies could discount the efficacy of HSCT and anti-HLA antibody screening should be performed before HSCT. Additionally, a second HSCT is feasible to prolong survival.

Emerging strategies for enhancing the homing of hematopoietic stem cells to the bone marrow after transplantation

Bone marrow failure is the primary cause of death after nuclear accidents or intentional exposure to high or low doses of ionizing radiation. Hematopoietic stem cell transplantation is the most potent treatment procedure for patients suffering from several hematopoietic malignancies arising after radiation injuries. Successful hematopoietic recovery after transplantation depends on efficient homing and subsequent engraftment of hematopoietic stem cells in specific niches within the bone marrow. It is a rapid and coordinated process in which circulating cells actively enter the bone marrow through the process known as transvascular migration, which involves the tightly regulated relay of events that finally leads to homing of cells in the bone marrow. Various adhesion molecules, chemokines, glycoproteins, integrins, present both on the surface of stem cells and sinusoidal endothelium plays a critical role in transvascular migration. But despite having an in-depth knowledge of homing and engraftment and the key events that regulate it, we are still not completely able to avoid graft failures and post-transplant mortalities. This deems it necessary to design a flawless plan for successful transplantation. Here, in this review, we will discuss the current clinical methods used to overcome graft failures and their flaws. We will also discuss, what are the new approaches developed in the past 10-12 years to selectively deliver the hematopoietic stem cells in the bone marrow by adopting proper targeting strategies that can help revolutionize the field of regenerative and translational medicine.

Risk factors associated with the development of moderate to severe chronic graft-versus-host disease after non-myeloablative conditioning allogeneic stem cell transplantation in patients with AML or MDS

Moderate to severe chronic graft-versus-host disease (cGVHD) is associated with high morbidity, hospital dependency and poor quality of life. In this study, we analyzed a well-defined consecutive series of 98 patients with acute myelogenous leukemia/myelodysplastic syndrome (AML/MDS) who received allogeneic stem cell transplantation with non-myeloablative (NMA) conditioning to determine risk factors associated with the severity of cGVHD. cGVHD was defined according to the 2005 National Institute of Health consensus criteria. Transfusions before transplantation, presence of HLA antibodies, composition of the graft (CD3+, CD19+, CD34+ cells), sibling or matched unrelated donor, female donor to male recipient, CMV serology and the development of acute GVHD (aGVHD), were considered potential risk factors. Multivariate Cox regression analysis identified the number of CD19+ 10⁶/kg (HR 2.79; 95% CI 1.35–5.74), CD3+ 10⁶/kg (HR 2.18; 95% CI 1.04–4.59) infused cells and the presence of patient HLA antibodies before transplantation (HR 2.34; CI 1.11–4.95) as significant risk factors for the development of moderate to severe cGVHD. In summary, we identified in a small, but well-defined cohort, 3 risk factors associated with the severity of cGVHD that should be validated in a larger multi-center study.

Kidney Transplantation: The Challenge of Human Leukocyte Antigen and Its Therapeutic Strategies

Kidney transplantation remains the treatment of choice for end-stage renal failure. When the immune system of the recipient recognizes the transplanted kidney as a foreign object, graft rejection occurs. As part of the host immune defense mechanism, human leukocyte antigen (HLA) is a major challenge for graft rejection in transplantation therapy. The impact of HLA mismatches between the donor and the potential recipient prolongs the time for renal transplantation therapy, tethered to dialysis, latter reduces graft survival, and increases mortality. The formation of pretransplant alloantibodies against HLA class I and II molecules can be sensitized through exposures to blood transfusions, prior transplants, and pregnancy. These preformed HLA antibodies are associated with rejection in kidney transplantation. On the other hand, the development of de novo antibodies may increase the risk for acute and chronic rejections. Allograft rejection results from a complex interplay involving both the innate and the adaptive immune systems. Thus, further insights into the mechanisms of tissue rejection and the risk of HLA sensitization is crucial in developing new therapies that may blunt the immune system against transplanted organs. Therefore, the purpose of this review is to highlight facts about HLA and its sensitization, various mechanisms of allograft rejection, the current immunosuppressive approaches, and the directions for future therapy.

Dynamic Detection of Anti-Human Leukocyte Antigen (HLA) Antibodies but not HLA-DP Loci Mismatches Can Predict Acute Graft-versus-Host Disease and Overall Survival in HLA 12/12-Matched Unrelated Donor Allogeneic Hematopoietic Stem Cell Transplantation for Hematological Malignancies

The National Marrow Donor Program and Center for International Blood and Marrow Transplant Research provided guidelines for the use of anti-HLA antibodies and HLA-DP-mismatched loci in unrelated donor hematopoietic stem cell transplantation (HSCT). However, a deeper understanding of other potentially useful biomarkers for predicting clinical outcomes in HLA-A, -B, -C, -DRB1, -DQB1, and -DQA1 (12/12)-matched unrelated donor HSCT is needed to further improve clinical outcomes. We tested HLA genotyping for 123 pairs of patients and donors. Anti-HLA antibodies using the Luminex method was applied to 123, 117, and 106 serum samples collected before and 1 month and 3 months after transplantation. The presences of anti-HLA antibodies at the 3 time points were 37.4% (46 of 123), 40.2% (47 of 117), and 22.6% (24 of 106). Mismatch of HLA-DPB1 and/or DPA1 allele between patient-donor pairs was 83.6% (92 of 110). Patients with anti-HLA antibodies had delayed platelet recovery. The presence of anti-HLA antibodies and their dynamic changes after transplantation were associated with increased occurrence of grades II to IV acute and chronic graft-versus-host disease (GVHD), higher treatment-related mortality, and reduced overall survival (OS) and disease-free survival, especially in acute myeloid leukemia and myelodysplastic syndrome patients. Multivariate analysis showed that presence of anti-HLA antibodies before transplantation was a risk factor for GVHD and OS. Furthermore, HLA-DP loci-matched subgroup showed a trend towards a lower rate of acute GVHD and a higher OS in the anti-HLA Abs-negative group. Our results suggest that dynamic changes of anti-HLA antibodies independently predict for a negative outcome of HSCT, independent of HLA-DP loci mismatches. Routine monitoring for anti-HLA antibody dynamics should be conducted before and after HSCT.

A glow of HLA typing in organ transplantation

The transplant of organs and tissues is one of the greatest curative achievements of this century. In organ transplantation, the adaptive immunity is considered the main response exerted to the transplanted tissue, since the main goal of the immune response is the MHC (major histocompatibility complex) molecules expressed on the surface of donor cells. Cell surface molecules that induce an antigenic stimulus cause the rejection immune response to grafted tissue or organ. A wide variety of transplantation antigens have been described, including the major histocompatibility molecules, minor histocompatibility antigens, ABO blood group antigens and endothelial cell antigens. The sensitization to MHC antigens may be caused by transfusions, pregnancy, or failed previous grafts leading to development of anti-human leukocyte antigen (HLA) antibodies that are important factor responsible for graft rejection in solid organ transplantation and play a role in post-transfusion complication Anti-HLA Abs may be present in healthy individuals. Methods for HLA typing are described, including serological methods, molecular techniques of sequence-specific priming (SSP), sequence-specific oligonucleotide probing (SSOP), Sequence based typing (SBT) and reference strand-based conformation analysis (RSCA) method. Problems with organ transplantation are reservoir of organs and immune suppressive treatments that used to decrease rate of rejection with less side effect and complications.