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Critical Reviews™ in Oncogenesis
SJR: 0.631 SNIP: 0.503 CiteScore™: 2

ISSN Imprimir: 0893-9675
ISSN On-line: 2162-6448

Critical Reviews™ in Oncogenesis

DOI: 10.1615/CritRevOncog.v9.i1.30
pages 35-42

Immunologic Nonresponsiveness to Tumors

Scott J. Antonia
Division of Medical Oncology, H. Lee Moffitt Cancer Center, Tampa, FL 33612
Martine Extermann
Division of Medical Oncology, H. Lee Moffitt Cancer Center, Tampa, FL 33612
Richard A. Flavell
Department of Immunobiology, School of Medicine, Yale University, New Haven, 06520, USA; Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520, USA

RESUMO

Over the past several years it has become clear that malignant cells express a variety of tumor associated antigens, and T cells reactive to these antigens have been identified. However, the T cells are not effective in rejecting tumors. In general, T cells that are not tolerized within the thymus have the potential to be rendered tolerant by one of three mechanisms. Immune deviation occurs when regulatory T cells which share a common precursor differentiate away from the phenotype required to effect a particular immune response. Anergy induction occurs when a T cell is stimulated through its T cell receptor in the absence of costimulation. Activation-induced cell death (AICD) is apoptosis of activated T cells upon subsequent encounter with antigen. There is emerging information that some of these mechanisms can be responsible for the lack of T cell responsiveness to tumor cells. Also, tumor cells can acquire attributes that interfere with an immune response, including down-regulation of MHC molecules or other molecules involved in antigen processing; secretion of the immunosuppressive cytokine TGFβ; and expression of the apoptosis-inducing surface molecule, Fas ligand. An expansion in our understanding of how tumor cells evade a T cell mediated death will provide insight into potential strategies to improve immunotherapeutic approaches to cancer patients.