Bakker Alexander B H, van den Oudenrijn Sonja, Bakker Arjen Q, Feller Nicole, van Meijer Marja, Bia Judith A, Jongeneelen Mandy A C, Visser Therese J, Bijl Nora, Geuijen Cecilia A W, Marissen Wilfred E, Radosevic Katarina, Throsby Mark, Schuurhuis Gerrit Jan, Ossenkoppele Gert J, de Kruif John, Goudsmit Jaap, Kruisbeek Ada M
Crucell Holland B.V., Leiden, The Netherlands.
Cancer Res. 2004 Nov 15;64(22):8443-50. doi: 10.1158/0008-5472.CAN-04-1659.
Acute myeloid leukemia (AML) has a poor prognosis due to treatment-resistant relapses. A humanized anti-CD33 antibody (Mylotarg) showed a limited response rate in relapsed AML. To discover novel AML antibody targets, we selected a panel of single chain Fv fragments using phage display technology combined with flow cytometry on AML tumor samples. One selected single chain Fv fragment broadly reacted with AML samples and with myeloid cell lineages within peripheral blood. Expression cloning identified the antigen recognized as C-type lectin-like molecule-1 (CLL-1), a previously undescribed transmembrane glycoprotein. CLL-1 expression was analyzed with a human anti-CLL-1 antibody that was generated from the single chain Fv fragment. CLL-1 is restricted to the hematopoietic lineage, in particular to myeloid cells present in peripheral blood and bone marrow. CLL-1 is absent on uncommitted CD34(+)/CD38(-) or CD34(+)/CD33(-) stem cells and present on subsets of CD34(+)/CD38(+) or CD34(+)/CD33(+) progenitor cells. CLL-1 is not expressed in any other tissue. In contrast, analysis of primary AMLs demonstrated CLL-1 expression in 92% (68 of 74) of the samples. As an AML marker, CLL-1 was able to complement CD33, because 67% (8 of 12) of the CD33(-) AMLs expressed CLL-1. CLL-1 showed variable expression (10-60%) in CD34(+) cells in chronic myelogenous leukemia and myelodysplastic syndrome but was absent in 12 of 13 cases of acute lymphoblastic leukemia. The AML reactivity combined with the restricted expression on normal cells identifies CLL-1 as a novel potential target for AML treatment.
急性髓系白血病（AML）因治疗抵抗性复发而预后不良。一种人源化抗CD33抗体（Mylotarg）在复发AML中显示出有限的缓解率。为了发现新的AML抗体靶点，我们使用噬菌体展示技术结合对AML肿瘤样本的流式细胞术，选择了一组单链Fv片段。一个选定的单链Fv片段与AML样本以及外周血中的髓系细胞谱系广泛反应。表达克隆鉴定出被识别为C型凝集素样分子-1（CLL-1）的抗原，这是一种先前未描述的跨膜糖蛋白。用从单链Fv片段产生的人抗CLL-1抗体分析CLL-1表达。CLL-1仅限于造血谱系，特别是外周血和骨髓中的髓系细胞。未定向的CD34(+)/CD38(-)或CD34(+)/CD33(-)干细胞上不存在CLL-1，而在CD34(+)/CD38(+)或CD34(+)/CD33(+)祖细胞亚群上存在。CLL-1在任何其他组织中均不表达。相比之下，对原发性AML的分析表明，92%（74例中的68例）的样本中存在CLL-1表达。作为一种AML标志物，CLL-1能够补充CD33，因为67%（12例中的8例）的CD33(-) AML表达CLL-1。CLL-1在慢性粒细胞白血病和骨髓增生异常综合征的CD34(+)细胞中表现出可变表达（10-60%），但在13例急性淋巴细胞白血病病例中的12例中不存在。AML反应性与在正常细胞上的限制性表达相结合，确定CLL-1是AML治疗的一个新的潜在靶点。
