Extraordinarily elevated CD33 expression in CD56+CD3– cells in the bone marrow of a patient with relapsed acute myeloid leukemia: a case report

Based on genetic risk allogeneic stem cell transplantation (allo-SCT) is the only curative treatment for some forms of acute myeloid leukemia (AML).However, post-transplantation relapse remains a frequent cause of transplantation failure.Natural killer (NK) cells and CD8+ T cells are important effector lymphocytes with pivotal roles in tumor surveillance and anti-tumor immune response.In this study, a 14-year-old female patient with AML was treated with allogeneic peripheral blood stem cell transplantation (allo-PBSCT).Bone marrow relapse was found 6 months later.Thereafter, the patient was treated with DAE (daunorubicin, cytosine arabinoside, and etoposide), followed by IAE (idarubicin, cytosine arabinoside, and etoposide), and then MA (mitoxantrone and cytosine arabinoside) regimens.A series of experiments including Wright-Giemsa stain analyses, cytogenetic analysis and flow cytometry were conducted to investigate the characteristic of the patient.Although there was a short remission after the DAE regimen, the patient experienced another relapse after finishing the MA regimen.The CD56 + CD3 -cells in the bone marrow showed severely impaired activation and anti-tumor function, while extraordinarily increased CD33 expression.Moreover, the proportion of multifunctional effector CD8 + T cells remained stable, though they had high PD-1 expression.These findings revealed the dysfunction of abnormal CD56 + CD3 -cells with high CD33 expression, which might be targetable and related to the relapsed/refractory AML after allo-SCT.