[The Foundation of Allogeneic Hematopoietic Stem Cell Transplantation and the Role of Clinical Laboratory Tests in This Field].

Despite the marked progress in the procedure of allogeneic hematopoietic stem cell transplantation (allo- HCT) as a curative therapy for hematological malignancy, we still need to resolve issues in clinical laboratory testing for the assessment of transplant patients. For example, minimal residual disease (MRD) negativity before transplantation is known to be associated with good survival, but the widespread use of the multi-color flow cytometry system is needed for the routine assessment of MRD. In addition, we should apply an appropriate testing system for counting harvested bone marrow cells with careful consideration of the meas- urement principle of testing equipment because bone marrow is different from peripheral blood in its compo- sition of cells and components. It is also a problem that the short tandem repeat-polymerase chain reaction (PCR) for the evaluation of donor chimerism is not covered by Japanese national health insurance. Tissue biopsy is useful for the diagnosis of graft-versus-host disease, transplantation-associated microangi- opathy, and sinusoidal obstruction syndrome. It is, however, potentially dangerous for patients who have thrombocytopenia after allo-HCT to undergo a biopsy. Non-invasive tests including surrogate makers for the diagnosis of those complications are highly desirable, but they have been not established. Moreover, limitations in the diagnosis of infection after allo-HCT by laboratory tests include the poor clinical utility of the viral antibody test after allo-HCT and the fact that quantitative virus PCR tests after allo-HCT are not covered by Japanesehational health insurance. The number of long-term transplant survivors has increased in recent years. We therefore need to focus on treatment strategies against long-term complications after allo-HCT and the improvement of the quality of life. Further progress in laboratory medicine in the allo-HCT field may contribute to the prevention of late complications and/or improvement of the quality of life. I.