“…Transient (Abelda et al, 1994;Carlos and Harlan, 1994;Rössler et al, 1992;Zimmermann et al, 1992). Leukocytes transmigrated into the brain release pro-inflammatory cytokines such as IL-1, IL-6, interferon (IFN)--y, and tumor necrosis factor (TNF)-a, which, in turn, up-regulate the expression of ICAM-1 on various cell types (Aloisi et al, 1992;Fabry et al, 1992;Frohman et al, 1989;Satoh et al, 1991b) and produce cytotoxic agents such as glutamate, oxygen radicals, and proteolytic enzymes (Zhuang et al, 1993). The release of pro-inflammatory cytokines (Kossmann et al, 1996(Kossmann et al, , 1997Morganti-Kossmann et al, 1997) and neurotoxins (e.g., glutamate) within the brain is thought to aggravate BBB damage, leading to vasogenic and cytotoxic brain edema formation (Greenwood, 1991;Weckerle, 1993), possibly resulting in a self-sustaining vicious circle (Cross et al, 1991;Staub et al, 1996).…”