Study of natural IgG antibodies against vascular endothelial growth factor receptor 1 in hepatocellular carcinoma.

Natural antibodies have been found to have anti-tumorigenic function. This study was designed to investigate whether natural IgG antibodies against vascular endothelial growth factor receptor 1 (VEGFR1) could suppress the growth of hepatocellular carcinoma (HCC) cells. Three HCC cell lines and A549 lung cancer cells were used for this study. They were grown, respectively, with human plasma positive or negative for anti-VEGFR1 IgG. Cell viability, apoptosis and VEGFR1 gene expression were examined. Three patients with HCC were recruited for a case study. The results showed that plasma anti-VEGFR1 IgG significantly inhibited the proliferation of all three HCC cell lines but not A549 cell line; the proportions of apoptotic cells were significantly higher in HCC cells treated with anti-VEGFR1 IgG positive plasma than those treated with IgG negative plasma. The expression of the VEGFR1 gene was significantly higher in HCC cells than A549 cells. Of three HCC patients who received transfusion of anti-VEGFR1 IgG positive plasma, two cases with stage B showed a good response to the treatment but one with distant metastasis did not. Human plasma IgG against VEGFR1 may be a promising agent for anti-HCC therapy.