OBJECTIVETo prepare a neutralizing monoclonal antibody (McAb) against vascular endothelial growth factor receptor KDR and study its biological activity.

METHODSExtracellular immunoglobulin (Ig)-like domain III of KDR (KDR III) was expressed in E. coli and purified by affinity chromatograph. Monoclonal antibody against KDR III was prepared by hybridoma technique. ELISA and FACS analysis were used to identify its specificity. Immunoprecipitation and [(3)H]-TdR incorporation assay were also used to detect the activity of anti-KDR McAb blocking the phosphorylation of KDR tyrosine kinase receptor and the influence on VEGF-induced mitogenesis of human endothelial cells.

RESULTSMcAb Ycom1D3 against KDR III was prepared which bound specifically to both the soluble KDR III and the cell-surface expressed KDR. It effectively blocked VEGF/KDR interaction and inhibited VEGF-stimulated activation of KDR expression on human endothelial cells. Furthermore, Ycom1D3 efficiently neutralized VEGF-induced mitogenesis of human umbilical vascular endothelial cells.

CONCLUSIONMcAb Ycom1D3 against KDR III may suppress the action of VEGF by blocking native vascular endothelial growth factor receptor KDR. It has potential clinical applications in the treatment of cancers and other diseases where pathological angiogenesis is involved.