QBEND/10單克隆抗體是一帶有γ重鏈與λ輕鏈的老鼠免疫球蛋白，能夠專一性地辨識人類造血幹細胞上的表面抗原CD34。體外細胞研究結果顯示，QBEND/10可以降低人臍靜脈血管內皮細胞（HUVECs）形成管柱的機會，這表明該抗體具有阻斷腫瘤血管生成的潛在優勢。我們通過串聯質譜法（tandem mass spectrometry）提供了一種蛋白質從頭測序（de novo protein sequencing）的方法，用以確定 QBEND/10重鏈可變區與輕鏈可變區的氨基酸序列。為了降低免疫原性（immunogenicity）以增加QBEND/10抗體應用至臨床的機會，我們利用表面重塑（resurfacing）的方式將QBEND/10鼠源抗體人源化。實驗結果證明，使用從頭測序（de novo protein sequencing）方式得到的QBEND/10氨基酸序列加上鼠源抗體人源化處理，人源化QBEND/10抗體保留了原本老鼠QBEND/10抗體該有的生物學功能，包括對人類CD34蛋白質的結合動力學以及降低內皮細胞形成管柱的作用。

QBEND/10 is a mouse immunoglobulin gamma 1 heavy chain and lambda light chain monoclonal antibody with strict specificity against human hematopoietic progenitor cell antigen CD34. In vitro study showed that QBEND/10 impaired tube formation of human umbilical vein endothelial cells (HUVECs), suggesting that the antibody may be of potential benefit in blocking tumor angiogenesis. We provided a de novo protein sequencing method through tandem mass spectrometry to identify amino acid sequences in variable heavy and light chains of QBEND/10. To reduce immunogenicity for clinical applications, QBEND/10 was further humanized using resurfacing approach. We demonstrate that the de novo sequenced and humanized QBEND/10 retains biological functions of the parental mouse counterpart, including binding kinetics to CD34 and blockage of tube formation of HUVECs.

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