Inhibition of VEGF-mediated endothelial cell proliferation in vitro and the antitumor effect by the adoptive transfer of immunoglobulins in vivo. (A) HUVECs were incubated with human VEGF (200 ng/mL) in the presence of various concentrations of immunoglobulins. Treatment with immunoglobulins from mice immunized with qVEGFR (•) resulted in apparent inhibition of endothelial cell proliferation compared with those from mice immunized with mVEGFR (▪) or ALUM (▴) alone. However, it had no effect on basic fibroblast growth factor (bFGF)–mediated endothelial cell proliferation (data not shown). (B) Adoptive transfer of immunoglobulins in vivo. The protective antitumor effect against Meth A cells was tested with purified immunoglobulins (50 mg/kg) from mice immunized with qVEGFR (•), mVEGFR (▪), or ALUM (▴). Treatment with immunoglobulins isolated from qVEGFR mice showed apparent protective antitumor effect, compared with controls. Results are expressed as means ± SEMs.