Читать книгу Blood and Marrow Transplantation Long Term Management - Группа авторов - Страница 122

Engraftment definitions based on early neutrophil and platelet recovery are insufficient to address late graft failure and rejection because nonmyeloablative and reduced intensity conditioning often results in mixed donor chimerism in one or more leukocyte lineages. This is rarely an issue for children with heavily pretreated malignancies, though falling chimerism is followed closely by some centers with the goal of preemptive intervention for impending relapse. Beyond this rationale, chimerism monitoring during LTFU is of questionable value for malignant diseases unless confirmation of residual donor hematopoiesis is necessary before donor lymphocyte infusion.

By contrast, mixed chimerism is essential in LTFU for NMDs, albeit dynamic patterns of lineage‐specific chimerism over months or years of follow‐up, and their meaning, remain to be firmly established for individual NMDs. What level of lineage‐specific chimerism is critical for durable correction of the underlying disease phenotype is also unclear for the full portfolio of NMDs [15,18]. Prospective LTFU studies are first needed to determine if complete donor chimerism is maintained in individual NMDs during extended LTFU. When mixed‐chimerism is present initially, or emerges over time, does the underlying disease phenotype, and/or autoimmunity, eventually return? For this reason, at least in primary immunodeficiency disease, the Primary Immunodeficiency Disease Transplant Consortium recommends lifelong, systematic and comprehensive assessment of lineage‐specific chimerism, plus numeric and functional immune reconstitution data, even if the patient is well and without signs of infection, to allow early detection and trajectory of possible declines in chimerism and immune function and so that intervention can occur before clinical complications of recurrent SCID emerge [17]. Testing begins no later than 3 months after HCT.