Which of the following does not describe a documented mechanism of tumor-mediated immune evasion?
Tumor cells have evolved mechanisms to escape and evade immune recognition. These mechanisms include various molecular genetic processes of eliminating MHC I from the tumor cell surface. Mutations inhibit efficient antigen processing and presentation. Tumor cells also block immune cells by secretion of suppressor proteins, most commonly TGF-b1, and other cytokine like "decoy" molecules to confuse the immune system. Antigenic variation is an immune escape mechanism ascribed to pathogenic microbes such as viruses for example.
Down regulation of class I MHC
Secretion of TGF-b
Secretion of decoy molecules
Antigenic variation
Immunology