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

Effects of gamma-interferon (IFN-gamma) on immune parameters in the 9L gliosarcoma model were examined. IFN-gamma increased class I major histocompatibility complex (MHC) expression in 9L cells in vitro. In vivo, intratumor injections of IFN-gamma 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.