Soluble Fas-ligand (sFasL) in human astrocytoma cyst fluid is cytotoxic to T-cells: another potential means of immune evasion.

Gliomas of all grades have been shown to express FasL, an apoptosis-inducing protein. Because of the ability of FasL to be cleaved from cell surfaces by metalloproteinases, soluble FasL can be released by FasL bearing cells into surrounding tissues. In the present study, we demonstrate the presence of sFasL in the cyst fluids of astrocytomas. Additionally, a human T-cell line, Jurkat, exposed to astrocytoma cyst fluid resulted in significantly increased cytotoxicity as compared to controls, an effect blocked by FasL neutralizing antibodies. This suggests that sFasL, may be utilized as a means of escaping immune surveillance by these tumors.