Establishment of a Novel Flow Cytometric Diagnostic Assay to Effectively Evaluate Immune Reconstitution After Hematopoietic Stem Cell Transplantation for Acute Lymphoblastic Leukemia

Primary Objective To assess immune reconstitution during the first 18 months following hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia (ALL), with a particular focus on the T-cell compartment (thymic regeneration and surrogate markers of cytotoxic function), using a dedicated panel developed within the EuroFlow consortium. Secondary Objectives To assess the impact of donor and recipient characteristics, graft-versus-host disease (GvHD) prophylaxis, and conditioning regimen on post-transplant immune reconstitution. To evaluate the correlation between immune reconstitution and the development of complications using unsupervised analysis.

Inclusion Criteria: * Patients who undergo first HSCT for ALL * Signing of informed consent by the patient (age\>18) or by parent/legal guardian (age \1° HSCT * ALL with specific genetic backgrounds which may impact on IR such as Down syndrome