In patients with hematopoetic stem cells transplantation and patients with diagnosis of thasma maj, in groups transplanted with ABO compatible and incompatible donors, post transplant engraving period, graft-host-host-celle-system, recycling, graft-host-host-celle transplantation, graft-host-host-celle-system, replications

INTRODUCTİON AND PURPOSE: The aim of this thesis is to evaluate the effect on transplant outcomes such as development of graft versus host disease of ABO blood group incompatibility between donor and recipient, development of veno-occlusive disease, engraftment days, relapse status and mortality and survival rates in pediatric patients with a diagnosis of transfusion-dependent thalassemia who underwent allogeneic hematopoietic stem cell transplantation. PATIENTS AND METHOD: A total of 201 patients aged 0-18 years with a diagnosis of transfusion-dependent thalassemia who underwent allogeneic hematopoietic stem cell transplantation were included between the years 1998 and 2021 at Akdeniz University Faculty of Medicine (AUFM), Department of Pediatrics, Hematology and Oncology, Stem Cell Transplantation Unit. The patients were first divided into two groups between the recipient and the donor as those with and without ABO blood group incompatibility. Among the recipient donor, patients in the group with ABO blood group incompatibility were divided into three groups as major incompatibility, minor incompatibility and mutual incompatibility. Due to the small number of patients in the mutual incompatibility group, to avoid errors in statistical results, subgroups were divided into minor+mutual discordant group and major discordant group. The groups were compared in terms of development of acute and chronic GVHD, VOD development, the number of total erythrocyte transfusions after transplantation, amount of erythrocyte per kilogram, the last day of erythrocyte transfusion, erythrocyte engraftment, leukocyte engraftment, platelet engraftment, delayed engraftment, relapse status, transplant-related mortality, mortality in the first 100 days after transplant, predicted overall survival time. Continuous variables summarized with median (the smallest and the biggest values); categorical variables summarized with numbers and percentages. ANOVA, unpaired t test, Kruskal-Wallis, Mann-Whitney u test were used in the analysis of quantitative independent data. Paired sample t-test, Wilcoxon test were used in the analysis of dependent quantitative data. Chi-square test and Fischer test were used in the analysis of qualitative independent data. Kaplan Meier was used for survival analysis. FINDINGS: All of the patients who underwent allogeneic HSCT consisted of transfusion-dependent thalassemia patients. While 16% of the patients had minor, 10% major and 5% mutual incompatibility; 32% of the patients had ABO blood group incompatibility. Acute GVHD in 16% of patients, chronic GVHD in 12% of patients, VOD in 15% of patients and autologous reconstitution developed in the 10% of the patients. While leukocyte engraftment occurred on the median 14th day, platelet engraftment occurred on the median 19th day. Erythrocyte engraftment occurred in 81% of patients within the first month after transplantation. The median amount of erythrocyte transfusion per kilogram after transplantation was 36 ml, and the median number of erythrocyte transfusions in total was 4. The effect of ABO blood group incompatibility between the donor and the recipient on development of acute and chronic GVHD (p=0.78 and p=0.29), VOD development (p=0.39),, the number of total erythrocyte transfusions after transplantation (p=0.97), amount of erythrocyte per kilogram (p=0.43), the last day of erythrocyte transfusion (p=0.99), leukocyte engraftment (p=0.31), platelet engraftment (p=0.97), autologous reconstitution status (p=0.81), transplant-related mortality (p=0.55), mortality in the first 100 days after transplant (p=0.75), predicted overall survival time (p=0.65), predicted diseased survival time (p=0.92) was not detected. RESULT: We are of the opinion that the ABO blood group incompatibility between the donor and the recipient does not constitute an obstacle for transplantation and does not significantly affect the results of allogeneic HSCT. However, so as to reach a definite opinion on this topic, it is necessary to have studies with patients diagnosed with transfusion-dependent thalassemia with a higher number of children. KEY WORDS: allogeneic hematopoietic stem cell transplantation, ABO blood group incompatibility, engraftment, graft versus host disease, veno-occlusive disease