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Infection and Immunity, March 2004, p. 1450-1462, Vol. 72, No. 3
0019-9567/04/$08.00+0 DOI: 10.1128/IAI.72.3.1450-1462.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
Vashti Lacaille,1,
Tara M. C. Hornell,1 Jennifer Huang,1 Supraja Narasimhan,1 David A. Relman,2,3* and Elizabeth D. Mellins1*
Department of Pediatrics,1 Departments of Microbiology and Immunology and Medicine, Stanford University School of Medicine, Stanford,2 Veterans Affairs Palo Alto Health Care System, Palo Alto, California3
Received 16 September 2003/ Returned for modification 23 October 2003/ Accepted 5 November 2003
Bordetella pertussis is the causative agent of whooping cough, a potentially lethal respiratory disease in children. In immunocompetent individuals, B. pertussis infection elicits an effective adaptive immune response driven by activated CD4+ T cells. However, live B. pertussis persists in the host for 3 to 4 weeks prior to clearance. Thus, B. pertussis appears to have evolved short-term mechanisms for immune system evasion. We investigated the effects of B. pertussis wild-type strain BP338 on antigen presentation in primary human monocytes. BP338 infection reduced cell surface expression of HLA-DR and CD86 but not that of major histocompatibility complex class I proteins. This change in cell surface HLA-DR expression reflected intracellular redistribution of HLA-DR. The proportion of peptide-loaded molecules was unchanged in infected cells, suggesting that intracellular retention occurred after peptide loading. Although B. pertussis infection of monocytes induced rapid and robust expression of interleukin-10 (IL-10), HLA-DR redistribution did not appear to be explained by increased IL-10 levels. BP338-infected monocytes exhibited reduced synthesis of HLA-DR dimers. Interestingly, those HLA-DR proteins that were generated appeared to be longer-lived than HLA-DR in uninfected monocytes. BP338 infection also prevented gamma interferon (IFN-
) induction of HLA-DR protein synthesis. Using mutant strains of B. pertussis, we found that reduction in HLA-DR surface expression was due in part to the presence of pertussis toxin whereas the inhibition of IFN-
induction of HLA-DR could not be linked to any of the virulence factors tested. These data demonstrate that B. pertussis utilizes several mechanisms to modulate HLA-DR expression.
Present address: Avigen, Inc., Alameda, CA 94502.
Present address: DiscoveRx Corporation, Fremont, CA 94538.
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