ISOLATION AND CHARACTERIZATION OF NEUTRALIZING MONOCLONAL-ANTIBODIES TO HUMAN VASCULAR ENDOTHELIAL GROWTH-FACTOR VASCULAR-PERMEABILITY FACTOR(121) (VEGF/VPF121)

We have established monoclonal antibodies (MAbs) against human vascular endothelial growth factor/vascular permeability factor(121) (VEGF/VPF121). Two (MV101 and MV303) of the 28 MAbs neutralized the mitogenic activity of VEGF/VPF121 on human umbilical vein endothelial cells (HUVEC) in a dose-dependent manner, Both of the MAbs reacted to VEGF/VPF121 and also VEGF/VPF165 with somewhat different binding properties in a sandwich-type enzyme-linked immunosorbent assay (ELISA), The binding of MV101 and MV303 to VEGF/VPF121 was competitive, but MV415, another anti-VEGF/VPF121 MAb without neutralizing activity, did not compete with either of the antibodies, MV101 and MV303 specifically recognized the native form of VEGF/VPF121 and VEGF/VPF165 in Western blotting. They did not react with VEGF/VPF when the antigens were fractionated under reducing conditions, These observations suggested that MV101 and MV303 might recognize the epitopes closely located on the configuration of VEGF/VPF121 molecule and the epitopes recognized by MV101 and MV303 may play an important role in the VEGF/VPF-receptor signal transduction, These MAbs significantly suppressed the growth of a human hepatoma, PLC/PRF/5, in vivo.