[摘要]：Background: Transforming growth factor beta 1 (TGF beta 1) has been proposed as a candidate for the transmission of radiation-induced bystander. signals. Aim: To assess the influence that the presence of latent TGF beta in the medium may have on the modulation of TGF beta 1 release and on its receptor (TGF beta R2) expression after irradiation of glioblastoma cells or after treatment with medium collected from gamma-irradiated cells. Materials and Methods: T98G cells cultured with a complete medium or a serum-free medium were irradiated with 0.25 and 1 Gy and the concentration of total TGF beta 1 was measured. Results and Conclusions: Irradiation of cells growing with a complete medium (i.e. a medium containing latent TGF beta 1, LTGF beta 1) caused a consistent dose-dependent decrease of the TGF beta 1 available in the medium. When LTGF beta 1 was not available in the medium (i.e. a medium without serum supplement), the levels of TGF beta 1 increased significantly. Changes in the pattern of expression of TGF beta R2 were evident only when a serum-free medium was used.
