Loss of MHC class II inducibility in hyperplastic tissue in Rb-defective mice

Retinoblastoma gene (Rb) defects occur frequently in human tumors. Studies of Rb-defective human tumor cell lines and Rb -/- murine embryonic fibrobla sts demonstrate that Rb is required for interferon-gamma (IFN-gamma) induce d major histocompatibility complex (MHC) class II expression. MHC class II expressing tumors generate anti-tumor immune responses associated with tumo r-specific infiltrating lymphocytes. The role of Rb in IFN-gamma induced MH C class II expression on an endogenous tumor was examined by immunohistoche mical staining for IAP and Rb on tissues from Rb +/- mice. MHC class II IA beta is not induced by IFN-gamma in Rb-deficient neoplastic cells. but rema ins inducible in related normal tissue. (C) 2001 Elsevier Science Ireland L td. All rights reserved.