Detection of minimal/measurable residual disease (MRD) in acute myeloid leukemia (AML) is important for guiding patient-specific clinical management. Natural killer (NK) cells can express various markers not typically associated with NK lineage, potentially confounding the detection of MRD by flow cytometry. We have observed CD33 expression on NK cells when evaluating for AML MRD in routine clinical practice in multiple patient samples. To characterize CD33 expression on NK cells, 40 peripheral blood or bone marrow samples with NK cells present at >5% of lymphocytes were selected for further assessment of NK cell phenotype and CD33 expression. Seven of the 40 samples (17.5%) were found to have CD33 expression on at least 5% of the NK cells. The CD33-positive NK cell population accounted for an average of 11.4% of NK cells (median 11.9%, range 8.0-15.3%) and 2.2% of total white cells (median 1.1%, range 0.1-10.1%). This NK cell subset expressed bright CD2, bright CD56, and dim CD16. On average, CD33 expression on NK cells was dimmer than on monocytes (mean median fluorescence intensity ratio 0.4; range 0.1-1.0). This study characterizes expression of CD33 on NK cells. Recognition of this pattern of antigen expression is critical in evaluating samples for MRD in patients with myeloid neoplasms, particularly AML.

中文翻译：

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自然杀伤细胞上CD33的表达可能是通过流式细胞仪检测急性髓细胞性白血病中残留疾病的潜在混杂因素。

急性髓细胞性白血病（AML）中最小/可测量的残留疾病（MRD）的检测对于指导特定于患者的临床管理非常重要。天然杀伤（NK）细胞可以表达通常与NK谱系不相关的各种标记，可能会混淆流式细胞仪对MRD的检测。在多个患者样品的常规临床实践中评估AML MRD时，我们已经观察到NK细胞上CD33的表达。为了表征NK细胞上CD33的表达，选择40个外周血或骨髓样本，其中NK细胞的淋巴细胞> 5％，以进一步评估NK细胞的表型和CD33的表达。在40个样本中，有七个（17.5％）被发现在至少5％的NK细胞上具有CD33表达。CD33阳性NK细胞群体平均占NK细胞的11.4％（中位数为11.9％，范围8）。占总白细胞的0-15.3％）和2.2％（中位数为1.1％，范围为0.1-10.1％）。该NK细胞亚群表达明亮的CD2，明亮的CD56和暗淡的CD16。平均而言，NK细胞上的CD33表达要比单核细胞上暗（平均中值荧光强度比为0.4；范围为0.1-1.0）。这项研究表征了CD33在NK细胞上的表达。这种抗原表达模式的识别对于评估髓样肿瘤（尤其是AML）患者的MRD样品至关重要。