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The presence of allo-antibodies in the serum of a recipient awaiting hematopoietic stem cell transplantation (HSCT) may have an impact on transfusion efficiency and/or donor choice, especially in the absence of an identical sibling donor. Prior to transplantation, donor specific anti-HLA (Human Leukocyte Antigen) antibodies (DSA) have a recognized effect on transplant outcome, correlated with the increasing MFI value and with the ability of such antibody to fix the complement fraction. Anti-platelet antibodies (anti-HLA class I and anti-HPA [Human Platelet Antigen]) are better involved in transfusion inefficiency and can be responsible for refractory status. ABO incompatibilities require a specific treatment of the graft in presence of high titer to avoid hemolytic adverse effects. Investigations of these antibodies should be carried out on a regular basis in order to establish appropriate transfusion recommendation, select an alternative donor when possible or adapt the source of cells. After transplantation, in case of delayed recovery or graft rejection, long term aplasia, persistent mixed chimerism or late release, and after elimination of the main clinical causes, a biological assessment targeted on the different type of antibodies will have to be performed in order to orient towards the cause or the appropriate therapy. Further studies should be carried out to determine the impact of anti-MICA antibodies and recipient specific anti-HLA antibodies, on the outcome of the transplantation.

International audience; Haploidentical hematopoietic stem cell transplantation has been growing steadily since 2012. The SFGM-TC has twice published guidelines concerning T-cell repleted haploidentical grafts with high dose cyclophosphamide post-transplantation. The 2013 workshop recommended using the non-myeloablative Baltimore protocol with bone marrow and developed prospective protocols to evaluate these transplantations. The 2015 workshop reported improved results of reduced conditioning regimens in Hodgkin's lymphoma and intensive conditioning in myeloid hemopathies, and a similar outcome with 10/10 HLA matched donor with the same disease-risk score thus raising the question of the qualifier "alternative" for haploidentical transplants. The current work concerns the criteria for selecting the donor. The main criterion remains the absence of anti-HLA antibodies directed against the donor present in the recipient sera (DSA - Donor Specific Antibodies). In case of DSA and in the absence of an alternative donor, desensitization protocols exist. The other criteria are impossible to prioritize: age, sex, CMV, and blood type. The degree of relatedness and the number of HLA incompatibilities do not seem to be a criterion of choice. The 'ideal' donor would be a young man, CMV-matched, without major ABO incompatibility with a marrow transplant. There is insufficient data for the KIR-ligand and NIMA/NIPA mismatch. Peripheral stem cell grafts appear to yield more acute GVHD than bone marrow grafts after intensive conditioning, but with comparable survival rates. Based on the literature review, the comparison of haploidentical with unrelated donors encourages inclusion in existing national protocols randomizing these different donors.

The recommendations of the French Health and Drug Safety Authorities (HAS/ANSM-Haute Autorité de santé/Agence nationale de sécurité du médicament) are known, but there are always new developments underway. With regards to CMV suppression, there is the introduction of platelet glycoprotein Ia and the Intercept (Amotosalem+UVA) inactivation method which addresses bacterial risk. The irradiation of platelets is included in the recommendations to ensure HEV-negative plasma post allograft. In terms of blood transfusion safety, these measures as well as the broader spectrum of Ia, particularly for arboviruses, are a real breakthrough. The survey conducted in clinical services and the services providing blood products for transfusion along with a literature review have shown that several improvements need to be made. The first is a reduction of transfusions of concentrated red blood cells with introduction at a threshold of 7g/dL during hospitalization of patients without a fragile clinical status. The second improvement would address transfusion of refractory thrombocytopenia, encouraging an increase in discussion between clinicians and those conducting the transfusion in order to consider different etiologies and to identify appropriate care protocols. Third would be the need for the transmission of information between the transplantation doctors and blood transfusion specialists in order to define an approach to transfusion care adapted to the patient's situation. It is important to inform and educate patients about transfusion protocols post allotransplant or autotransplant. It must be clearly communicated to patients that they should always have on their person their blood group documentation. This is especially true when receiving care for a hemopathy or an autologous transplant. If undergoing an allogeneic transplant, patients should also carry transfusion guidelines post autotransplant or post allotransplant along with the phone numbers for the stem cell transplantation department and the blood transfusion center responsible for their care.

Within the context of the SFGM-TC's 6th workshop series on the harmonization of clinical practices, our workshop proposes a standardization of the informed consent process for hematopoietic stem cell donors and recipients leading up to an autologous or allogenic transplantation. All informed consent was for bone marrow or peripheral stem cell donors, and mononuclear/lymphocyte donors according to usual procedures. The informed consent for autologous and allogenic related or unrelated adults and pediatric transplantation patients have been included. A first step has been conducted for collecting in advance the informed consent forms used routinely in all francophone transplantation centers. In a second step, a comprehensive version has been re-written by a multidisciplinary team. For the purposes of understanding the risks and advantages, language has been carefully considered and streamlined. In the third step, texts were sent to stem cell transplantation experts, experts at the French biomedical agency (agence de la biomédecine [ABM]), law specialists, members of the ethical committee of the French society of hematology and several transplant recipients to be edited and proofread.