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Infection and Immunity, May 2008, p. 2138-2148, Vol. 76, No. 5
0019-9567/08/$08.00+0 doi:10.1128/IAI.01252-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
B and Interferon Regulatory Factors 1 and 8 in Human Dendritic Cells
Michael J. Donovan,
Vinita Tripathi,
Marcelo Ramalho-Ortigao, and
Mary Ann McDowell*
Center for Global Health and Infectious Diseases, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556
Received 12 September 2007/ Returned for modification 11 October 2007/ Accepted 16 February 2008
The salient feature of dendritic cells (DC) is the initiation of appropriate adaptive immune responses by discriminating between pathogens. Using a prototypic model of intracellular infection, we previously showed that Leishmania major parasites prime human DC for efficient interleukin-12 (IL-12) secretion. L. major infection is associated with self-limiting cutaneous disease and powerful immunity. In stark contrast, the causative agent of visceral leishmaniasis, Leishmania donovani, does not prime human DC for IL-12 production. Here, we report that DC priming by L. major infection results in the early activation of NF-
B transcription factors and the up-regulation and nuclear translocation of interferon regulatory factor 1 (IRF-1) and IRF-8. The inhibition of NF-
B activation by the pretreatment of DC with caffeic acid phenethyl ester blocks L. major-induced IRF-1 and IRF-8 activation and IL-12 expression. We further demonstrate that IRF-1 and IRF-8 obtained from L. major-infected human DC specifically bind to their consensus binding sites on the IL-12p35 promoter, indicating that L. major infection either directly stimulates a signaling cascade or induces an autocrine pathway that activates IRF-1 and IRF-8, ultimately resulting in IL-12 transcription.
Published ahead of print on 3 March 2008.
Present address: Department of Epidemiology and Public Health, School of Medicine, Yale University, New Haven, CT 06520.
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