Effects of γ-interferon on major histocompatibility complex antigen expression and lymphocytic infiltration in the 9L gliosarcoma brain tumor model: implications for strategies of immunotherapy

Effects of γ-interferon (IFN-γ) on immune parameters in the 9L gliosarcoma model were examined. IFN-γ increased class I major histocompability complex (MHC) expression in 9L cells in vitro. In vivo, intratumor injections of IFN-γ led to increased numbers of inflammatory cells within the tumor and class II + mononuclear phagocytes at its periphery, and increased MHC class I or II expression by endothelial and ependymal cells. Class I expression in 9L cells themselves was not increased. This suggests that there may be inhibition of class I induction in vivo for certain cell types, for which immunotherapies based on non-MHC restricted mechanisms may be more effective.