Basic fibroblast growth factor (bFGF) and vascular endothelial cell growth factor (VEGF) were demonstrated to be important factors sustaining the growth of Kaposi's sarcoma. RF cells were used to provide a model to study the pathogenesis of Kaposi's sarcoma. In this paper, we demonstrated that bFGF is present in the RF cells, cultured media, and tissues from monkey. The biological activities of bFGF on RF cells were also studied in vitro with serum-free media. The bFGF from serum-free conditioned media is biologically active to stimulate RF cells in certain media condition. The mitogenic effect was abrogated by sheep neutralizing anti-bFGF antibody. Furthermore, the effect of antibody was reversed by the addition of exogenous bFGF. ELISA measurements indicating the growth potency of conditioned media correlated with the amount of bFGF in the conditioned media. The data from flow cytometry demonstrated the co-existence of SRV-2 and bFGF among RF cells and RF tissues. Immunohistochemical staining of RF tissue blocks for bFGF revealed that bFGF was present in the tumor and the presence of bFGF was not caused by the artifact of tissue culture. These results indicate that bFGF is an important growth factor to promote RF cell growth in vitro and RF tumor in vivo. Further studies are required to determine the relationship between the interaction of bFGF, SRV-2, and VEGF. This model also provides an adequate alternative to the model induced by simian immunodeficiency virus (SIV) to study the Kaposi's sarcoma.
