Increased concentrations of transforming growth factor β1 and β2 in the plasma of patients with glioblastoma

Recently, several in vitro studies have demonstrated production of the potent immunosuppressive cytokine transforming growth factor beta (TGF-beta)2 in glioblastoma cell lines. Systematic studies of the concentration of TGF-beta isoforms in the plasma of patients harboring intracerebral tumors do not exist. In the present study, the concentrations of TGF-beta 1 and TGF-beta 2 in platelet-poor plasma of 21 patients with glioblastoma before and after extensive resection were measured by specific ELISA systems and related to survival. The plasma concentrations of latent TGF-beta 1 of patients with glioblastoma prior to surgery were significantly higher in comparison to healthy control probands, but not to patients with multiple sclerosis (MS). Furthermore, latent TGF-beta 2 was found to be significantly increased in the plasma of patients with glioblastoma in comparison to healthy control probands and patients with MS. After extensive resection of the tumor, the value of latent TGF-beta 2 evidently decreased. Interestingly, the concentration of latent TGF-beta 2 prior to surgery was correlated with survival and a strong relationship was found between the survival and the difference of latent TGF-beta 2 levels prior to surgery minus the TGF-beta 2 concentrations 7 days after surgery. A higher difference in these plasma concentrations > 6 ng/ml vs. < 6 ng/ml clearly correlates with a longer survival time. In conclusion, this study suggests that glioblastoma does secret TGF-beta 2 in vivo and that TGF-beta 2 may play an important role in glioblastoma patients.