Abnormalities by Multicolor Flow Cytometry for Detection of Minimal Residual Disease in Recipients of Allo-HSCT Originating from Donors: A Cohort Study

Objective: In minimal residual disease (MRD) analysis after allogeneic hematopoietic stem cell transplantation (allo-HSCT), abnormal immunophenotyping is commonly considered as evidence of a secondary recurrence or complications, leading to overtreatment. We aimed to confirm whether such phenotypic abnormality might originate from donors using multicolor flow cytometry (MFC). Materials and Methods: The MRD of bone marrow specimens of 3395 patients who had received allo-HSCT were analyzed using the conventional two-tube, eight-color MFC panel. The frequencies of abnormal immunophenotypes were also evaluated in three groups of patients without malignancies. Results: The frequency of new abnormal polymorphisms was 0.088% (3/3395) among patients who received allo-HSCT. The abnormal cells seen in three patients in complete remission were Fcγ receptor IIIB (FcγRIIIB) gene deletion (CD16- neutrophils), CD2-CD159a-CD159c Conclusion: Abnormalities in recipients of allo-HSCT detected by MRD analysis may originate from their donors. Screening of donor specimens with a suitable two-tube, eight- to ten-color MFC panel may be a promising method for minimizing misdiagnoses.