Increased monocyte chemoattractant protein-1 expression by tumor necrosis factor-alpha can mediate macrophage infiltration in gliomas

We compared the in vitro effects of various cytokines on the expression of monocyte chemoattractant protein-1 (MCP-1) in glioma cell lines and found that MCP-1 expression was highly induced by tumor necrosis factor-alpha (TNF alpha) and interleukin-1 beta. The intra-tumoral injection of TNF alpha in rat glioma model increased the in vivo expression of MCP-1 at 1 to 12 h after the injection and induced macrophage infiltration into tumor tissue. The injection of TNF alpha into post-operative tumor cavity of human malignant glioma also increased the concentration of MCP-1 in the cavity fluid at 24 to 38 h after injection. These data, together with the previous finding that the growth of transplanted MCP-1-transfected cells was significantly inhibited by infiltrated macrophages, suggest that injection of TNF alpha inhibits turner growth via the induction of MCP-1 expression.