Table of Contents Author Guidelines Submit a Manuscript
Clinical and Developmental Immunology
Volume 2012, Article ID 937253, 14 pages
http://dx.doi.org/10.1155/2012/937253
Review Article

Modulation of Tumor Tolerance in Primary Central Nervous System Malignancies

1Department of Pediatrics, Georgia Health Sciences University, 1120 Fifteenth Street, BT-1852, Augusta, GA 30912, USA
2Immunotherapy Center, Georgia Health Sciences University, 1120 Fifteenth Street, CN-4141A, Augusta, GA 30912, USA
3GHSU Cancer Center, Georgia Health Sciences University, 1120 Fifteenth Street, CN-4141A, Augusta, GA 30912, USA

Received 16 July 2011; Revised 29 September 2011; Accepted 3 October 2011

Academic Editor: C. Morimoto

Copyright © 2012 Theodore S. Johnson et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Central nervous system tumors take advantage of the unique immunology of the CNS and develop exquisitely complex stromal networks that promote growth despite the presence of antigen-presenting cells and tumor-infiltrating lymphocytes. It is precisely this immunological paradox that is essential to the survival of the tumor. We review the evidence for functional CNS immune privilege and the impact it has on tumor tolerance. In this paper, we place an emphasis on the role of tumor-infiltrating myeloid cells in maintaining stromal and vascular quiescence, and we underscore the importance of indoleamine 2,3-dioxygenase activity as a myeloid-driven tumor tolerance mechanism. Much remains to be discovered regarding the tolerogenic mechanisms by which CNS tumors avoid immune clearance. Thus, it is an open question whether tumor tolerance in the brain is fundamentally different from that of peripheral sites of tumorigenesis or whether it simply stands as a particularly strong example of such tolerance.