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Blood, 15 February 2006, Vol. 107, No. 4, pp. 1434-1444. Prepublished online as a Blood First Edition Paper on October 27, 2005; DOI 10.1182/blood-2004-09-3445. This Article Full Text Full Text (PDF) All Versions of this Article: 2004-09-3445v1 107/4/1434    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Buch, T. Articles by Förster, I. Search for Related Content PubMed PubMed Citation Articles by Buch, T. Articles by Förster, I. Related Collections Immunobiology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  IMMUNOBIOLOGY MHC class II expression through a hitherto unknown pathway supports T helper cell-dependent immune responses: implications for MHC class II deficiency Thorsten Buch, Bojan Polic, Björn E. Clausen, Susanne Weiss, Özlem Akilli-Ozturk, Cheong-Hee Chang, Richard Flavell, Ansgar Schulz, Stipan Jonjic, Ari Waisman, and Irmgard Förster From the Institute for Medical Microbiology, Immunology and Hygiene, Technical University of Munich, Munich, Germany; Institute for Genetics, University of Cologne, Cologne, Germany; the Department of Histology and Embryology, Medical Faculty University of Rijeka, Rijeka, Croatia; the Department of Cell Biology and Histology, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, the Netherlands; the Department of Microbiology and Immunology, Walther Oncology Center, Indiana School of Medicine, Indianapolis, IN; the Section of Immunobiology and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT; the University Children's Hospital, University of Ulm, Ulm, Germany; I. Medizinische Klinik und Poliklinik, University of Mainz, Mainz, Germany; and Institut für Umweltmedizinsche Forschung gGmbH, Heinrich-Heine-University, Düsseldorf, Germany. MHC class II (MHCII) deficiency or bare lymphocyte syndrome (BLS) is a severe immunodeficiency characterized by deficient T helper (Th)-cell-dependent immunity. The disease is caused by defects of the MHCII promoter complex resulting in low or absent MHCII expression. We demonstrate in a murine model of MHCII deficiency (RFX5- or CIITA-deficient mice) that residual MHCII expression by professional antigen-presenting cells (APCs) is sufficient to support activation of adoptively transferred Th cells. Furthermore, upon transplantation of WT thymic epithelium, we observed development of endogenous Th cells with restoration of Th-cell-dependent antibody responses and immunity to cytomegalovirus infection, thus opening the possibility of an alternative treatment regimen for BLS. Residual MHCII expression was further induced by the presence of Th cells and also other stimuli. Analysis of CIITA/RFX5 double-deficient animals revealed that this inducible MHCII expression is genetically independent of the known promoter complex and thus constitutes an alternative MHCII expression pathway. In these experiments, we also detected a novel repressive function of the RFX complex in the absence of CIITA. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

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