Improved Myeloablative Allogeneic Hematopoietic Stem Cell Transplantation Protocol for the Treatment of Epstein Barr Virus T/NK Lymphoproliferative Disease (EBV-T/NK LPD) and Prevention of Post Transplant Graft-versus-host Disease

"For children at high risk of GVHD, one of the following conditions must be met (haploidentical donors must meet one condition, while unrelated donors must meet two conditions):~1. The donor is ≥40 years old;~2. The donor is an unrelated donor with ≥1 locus mismatch, a haploidentical female donor, or collateral consanguinity (e.g., cousin, uncle/aunt);~3. Pre-transplant CD3 count ≥4 x 10\^8/kg;~4. The primary disease is in an HLH (hemophagocytic lymphohistiocytosis) flare or active disease phase;~5. ATG (or biologically equivalent doses of ATLG \[1:2\] or ALG \[1:20\]) \<10mg/kg. Combining recombinant anti-CD25 humanized monoclonal antibody with conventional pretreatment regimen, before peripheral blood stem cell transfusion (i.e. 0d) and+3d, 1mg/kg，\<40kg the maximum dose should not exceed25mg/dose, ≥40kg 1mg/kg, and the maximum dose should not exceed 50mg/dose."