Abnormalities Detected by Multicolor Flow Cytometry Detection of MRD in Allo-HSCT Recipients Originating from Donors: A Cohort Study.

Abstract

In minimal residual disease (MRD) analysis after allogeneic hematopoietic stem cell transplantation (allo-HSCT), abnormal immunophenotyping are commonly considered as secondary recurrences or complications that lead to overtreatment. We aimed to confirm whether this phenotypic abnormality might be from the donor using multicolor flow cytometry (MFC). The MRD of the bone marrow (BM) specimens of 3395 patients who had received an allo-HSCT were analyzed using the conventional two-tubes eight-color MFC panel. The frequency of abnormal immunophenotypes were evaluated in three groups of non-malignance individuals. The frequency of new abnormal polymorphism was 0.088% (3/3395) in patients that received an allo-HSCT. Abnormal cells in three patients in complete remission were Fcγ receptor IIIB (FcγRIIIB) gene deletion (CD16- neutrophils), CD2-CD159a-CD159c+ natural killer (NK) cells, and monoclonal B lymphocytosis (MBL). In addition, abnormal T cells (CD4+CD8+) were detected in one donor before allo-HSCT. Identical abnormalities were found in the peripheral blood of the corresponding donors of the three patients via MFC. In the non-malignant population, the incidence of FcγRIIIB deletion was 0.2% (11/5256), NK cells with the absence of CD2 and single positive CD159c was 0.05% (1/2000), and monoclonal CD4/CD8 double-positive T cells was 0.05% (1/2000), and the incidence of MBL was 1.3% (14/1100). The frequency of NK cells with the absence of CD2 was 1.3% (1/79) and with CD8dim was 14% (11/79) in NK cell lymphoma. These abnormalities could be identified by the two-tubes eight-ten color MFC panel: cκ/cλ/CD19/ CD5/CD20/CD38/CD45/CD56 (adding CD10 and CD34 as the ninth and tenth-color), CD16+CD56/CD5/CD3/ CD7/ CD4/ CD8/CD2/CD45 (adding CD117 as the ninth-color). Abnormalities in recipients of an allo-HSCT detected by MRD may originate from the donors. Screening of donor specimens with a suitable two-tubes eight-ten color MFC panel may be a promising method to minimize misdiagnoses.