Clinical Observation Of 12 Cases Of Donor Lymphocyte Transfusion After Transfusion-Dependent Thalassemia In Transplantation

ObjectiveBy summarizing the clinical conditions of 12 patients with transfusion-dependent thalassemia who received donor lymphocyte infusion(DLI)after transplantation,to explore the role and safety of DLI in patients with mixed chimerism(MC)after transplantation.Materials and MethodsThe clinical data of 12 patients with MC after transfusion-dependent thalassemia transplantation who were diagnosed and treated in the third pediatric ward of our hospital from May 2018 to February 2021 were collected,including the pretreatment plan and the graft-versus-host disease(GVHD)prevention plan,donor chimerism(DC)detection method,DLI strategy,etc.And analyze and summarize the changes in the DC rate of patients after DLI and related complications.Results1.A total of 12 cases were included in this study,including 10 male patients and 2 female patients,with a median age of 5 years and 6 months(2 years and10 months to 13 years and 5 months).10 patients received matched sibling donor hematopoietic stem cell transplantation,and 2 patients received haploidentical hematopoietic stem cell transplantation.All 12 patients successfully obtained hematopoietic reconstitution after transplantation.In the first DC rate test,11 patients obtained complete chimerism(CC),and one patient obtained MC 1 grade.No severe GVHD occurred in all patients from the post-transplant to the pre-DLI stage.2.During the follow-up,the DC rate of the 12 patients showed a continuous downward trend.The median time for the DC rate to start to decline was 63 days(43 days to 128 days),and the DC rate did not improve after the immunosuppressant was stopped.The detection of DC rate before the first DLI indicated that 8 patients were MC2 and 4 patients were MC3.12 patients received a total of 14 DLI treatments,including 10 patients received 1 DLI each,and 2 patients received 2 DLI treatments.After the infusion,the patient’s DC rate gradually increased,and finally 10 patients obtained CC.In addition,2patients presented with MC,one with persistent MC1 grade and one with persistent MC2 grade,but there was no return to blood transfusion and no GVHD occurred.3.12 patients were in the process of monitoring the DC rate after transplantation.It was found that although the DC rate of patients dropped to the lowest point(67.83%-87%),the RBC and Hb did not decrease significantly during the same period.4.12 patients experienced acute GVHD in 5 patients after 14 times of DLI.3 patients showed Ⅰ-Ⅱ acute GVHD,and 2 patients showed Ⅲ-Ⅳ acute GVHD.Among them,Ⅰ-Ⅱ degree acute GVHD occurred in patients with matched sibling hematopoietic stem cell transplantation,and Ⅲ-Ⅳ degree acute GVHD occurred in patients with haploidentical hematopoietic stem cell transplantation.5.12 patients experienced short-term hematopoietic dysfunction after 14 times of DLI.2 cases occurred in matched sibling hematopoietic stem cell transplantation,and 2 cases occurred in haploidentical hematopoietic stem cell transplantation.The 2 cases of matched sibling transplantation patients showed mild symptoms and returned to normal hematopoietic state by themselves after close observation.The blood routine of the 2 haploidentical transplant patients showed three-line reduction,and the duration was longer than that of the fully matched patients,requiring transfusion of red blood cells,platelets and other components of blood,as well as related supportive treatments.6.The median follow-up time was 588 days(203 days to 997 days).Among the 12 patients,9 patients were CC.1 was MC1,and 1 was MC2.Another patient died due to concurrent central nervous system cytomegalovirus infection.Conclusion1.The median time to develop MC after transplantation for the 12 thalassemia patients is 63 days.It is necessary to closely monitor changes in the DC rate before and after this.2.DLI can effectively prevent the DC rate from falling and effectively promote its recovery.3.GVHD is the main complication of DLI.Among them,the severity of GVHD in matched sibling patients undergoing DLI is significantly lower than that of haploidentical transplant patients.4.DLI for haploidentical transplantation patients requires a careful decision.After DLI,measures to prevent GVHD and close monitoring of the condition can be adopted.5.The occurrence of MC in thalassemia patients is not parallel to the recurrence of the disease,and the decline of DC rate is earlier than the hematological changes.