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Journal of Biomedicine and Biotechnology
Volume 2007, Article ID 79401, 7 pages
Review Article

Regulation of Defense Responses against Protozoan Infection by Interleukin-27 and Related Cytokines

1Department of Biomolecular Sciences, Faculty of Medicine, Saga University, Saga 849-8501, Japan
2Department of Parasitology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan

Received 26 November 2006; Revised 2 February 2007; Accepted 26 February 2007

Academic Editor: Ali Ouaissi

Copyright © 2007 Hiroki Yoshida 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.


Cytokine-mediated immunity is crucial in the defense against pathogens. Recently, IL-23 and IL-27 were identified, which along with IL-12 belong to the IL-12 cytokine family. IL-27 is pivotal for the induction of helper T cell (Th) 1 responses while IL-23 is important for the proliferation of memory type Th1 cells. Recent studies revealed that IL-27 also has an anti-inflammatory property. In some protozoan infection, various proinflammatory cytokines were over produced causing lethal inflammatory responses in IL-27 receptor-deficient mice. The anti-inflammatory effect of IL-27 depends, at least partly, on inhibition of the development of Th17 cells, a newly identified Th population that is induced by IL-23 and is characterized by the production of the inflammatogenic cytokine, IL-17. IL-27 thus has a double identity as an initiator and as an attenuator of immune responses and inflammation. With the discoveries of the new IL-12-related cytokines and Th17 cells, Th development is facing a new paradigm.