Abstract
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.