Potential immune escape mechanisms of tumors: MHC class I molecules - Enemies or friends

Abstract

It is generally accepted that tumor development is a multifactorial process which is caused by a sequential accumulation of different genetic alterations leading to aberrant cell cycle control, instability of genomic integrity as well as decrased recognition by the immune system. During the last decade, the tumor-host interaction has been well defined. It has been demonstrated that professional antigen presenting cells (APC), macrophages, natural killer (NK) cells, NKT cells and in particular T-lymphocytes play a key role in anti-tumor immunity. In general, immune cells monitor MHC class I-presented antigenic peptides. Presentation of self peptides by MHC class I molecules results in the generation of tolerance. In contrast, presentation of viral or tumor-derived foreign antigens leads to the induction of lysis by CD8+ cytotoxic T lymphocytes (CTL). © 2008 Springer.