In CNS diseases, including highgrade gliomas, activated macrophages migrate away from their perivascular residence to the site of pathology, where they participate in the in ammatory response.Macrophages are not frequently encountered in lowgrade astrocy to mas, but their numbers increase with Methscopolamine increasing histo logic grade of the tumor, being highest in GBM, and IL levels in ast rocytic neoplasms rough ly correlatewith the number of macrophages in the specimen.Moreover, the density of the macrophage in ltrates correlateswith the degree ofmicrovascu lar proliferation.M icrog lia are a second population of primary CNS cel ls that are derived from the monocy te macrophage lineage and express IL, especially following activation, although their role in tumorigenesis is not establ ished. In Rebeprazole sodium addition to their abilities to directly release IL, macrophages andmicroglia a lso secrete TNF and IL, which could potentially act on tumor cells to induce the release of additional IL. In exper iments on human ast rocy toma spec imens that included in situ hybr id izat ion and immunoh isto chem istry, IL expression washighest in pseudopal isad ing cel ls su rround ing necrosis and was a lso noted in the perivascu lar reg ion, likely due to in ammatory cel ls. The localization of IL expression to pseudopalisading cells, which are known to be hypoxic and express high levels of hypox iainducible factor, suggested that hypox iamight lead to increased IL expression.Indeed, enhanced IL expression can be demonstrated in the hypoxic centers of glioma spheroids grown in culture and in glioma cells grown under anoxic conditions.Further, the pattern of IL mRNA expression in pseudopalisades, as demonstrated by in situ hybridization, is punctate, while that of VEGF is more uniform.Thus, IL expression in response to anoxia appears to be distinct from VEGF, in terms of both its spatial and its temporal characteristics.The results of both nuclear runon experiments and transcript ional inh ibit ion ind icate that increased IL levels in anoxic gliomas are due to increased transcriptional activity.Binding of the transcription factor AP to the IL promo ter inc reasesd ramat icallyunder anoxia in glioma cells, while that of NFB and CEBP NFIL does not, implicating AP as a critical oxygensensitive transcriptional factor complex in IL production. Results from some studies suggest that NFB might also participate in the hypoxiaIL expression response. Unlike VEGF expression, the oxygensensitive transcript ion of IL is independent of T P status ingl ioma cells and is thus unlikely to be related to hypoxic induction of p. In addition to stimulation by low oxygen, IL expression is promoted by other conditions in the tumor microenvironment, such as reducedglucose levels, am ino acid deprivation, low pH, and reactive oxygen species, all of which are associated with nutrient deprivation. The exact role of IL in the biology of astrocytomas is not clear.Among many potential roles, it could act as a more general proin ammatory fac tor released in response totissue stress and necro sis, an autocrine grow th factor secreted by tumor cells to promote their own growth.