Induction of macrophagic prostaglandin E2 synthesis by glioma cells

Object It has been reported that glioma cells produce prostaglandin (PG)E2, which promotes the growth of tumor cells and possesses immunosuppressive activity, and that cyclooxygenase (COX) inhibitors impede tumor growth and infiltration. Macrophages in tumor-bearing hosts are activated to produce PGE2, which induces an immunosuppressive state. Note, however, that the precise mechanism by which PGE2 induces an immunosuppressive state is still unclear. In this study, the authors investigated the mechanism of PGE2 production in glioma-bearing hosts. Methods The human and murine glioma cells that were studied did not produce a significant amount of PGE2. However, the coculture of human peripheral blood mononuclear cells or murine peritoneal macrophages with glioma cells or conditioned glioma medium led to the production of a large amount of PGE2. In contrast, production of tumor necrosis factor and interleukin (IL)-12p70 by macrophages and cytotoxic T lymphocyte induction were suppressed by culturing with con...