Abstract
Astrocytes and microglial cells cultured from murine brain were stimulated to produce tumor necrosis α (TNF) by exposure to lipopolysaccharide (LPS). TNF α production began within 2 h with maximum production between 4 and 8 h after atimulation. Clinically relevant low (2 Gy), but not high (8 Gy), doses of radiation significantly increased TNF production by astrocytes and microglial cells in response to LPS. The radiation effect was even more marked with multiple 2 Gy doses. TNF is cytotoxic for oligodendrocytes and for certain tumor cells. It increases vascular permeability and enhances immune responses as well as having biological effects. It is conceivable that production of TNF by astrocytes and microglial cells during clinical radiation theraphy might influence the responses of tumor and/or normal CNS tissues. © 1991.