scholarly journals Dendritic Cells Inhibit the Progression of Listeria monocytogenes Intracellular Infection by Retaining Bacteria in Major Histocompatibility Complex Class II-Rich Phagosomes and by Limiting Cytosolic Growth

2010 ◽  
Vol 78 (7) ◽  
pp. 2956-2965 ◽  
Author(s):  
Marlena M. Westcott ◽  
Curtis J. Henry ◽  
Jacqueline E. Amis ◽  
Elizabeth M. Hiltbold
Keyword(s):  
Bone Marrow ◽  
Dendritic Cells ◽  
Major Histocompatibility Complex ◽  
Listeria Monocytogenes ◽  
Major Histocompatibility Complex Class ◽  
Class Ii ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Mhc Ii ◽  
Histocompatibility Complex

ABSTRACT Dendritic cells (DC) provide a suboptimal niche for the growth of Listeria monocytogenes, a facultative intracellular bacterial pathogen of immunocompromised and pregnant hosts. This is due in part to a failure of large numbers of bacteria to escape to the cytosol, an essential step in the intracellular life cycle that is mediated by listeriolysin O (LLO). Here, we demonstrate that wild-type bacteria that failed to enter the cytosol of bone marrow-derived DC were retained in a LAMP2+ compartment. An isogenic L. monocytogenes strain that produces an LLO protein with reduced pore-forming activity had a severe escape and growth phenotype in DC. Few mutant bacteria entered the cytosol in the first 2 h and were instead found in LAMP2+, major histocompatibility complex class II+ (MHC-II+) H2-DM vesicles characteristic of MHC-II antigen loading compartments (MIIC). In contrast, the mutant had a minor phenotype in bone marrow-derived macrophages (BMM) despite the reduced LLO activity. In the first hour, DC phagosomes acidified to a pH that was, on average, half a point higher than that of BMM phagosomes. Unlike BMM, L. monocytogenes growth in DC was minimal after 5 h, and consequently, DC remained viable and matured late in infection. Taken together, the data are consistent with a model in which phagosomal maturation events associated with the acquisition of MHC-II molecules present a suboptimal environment for L. monocytogenes escape to the DC cytosol, possibly by limiting the activity of LLO. This, in combination with an undefined mechanism that controls bacterial growth late in infection, promotes DC survival during the critical maturation response.

scholarly journals Persistent Ehrlichia chaffeensis Infection Occurs in the Absence of Functional Major Histocompatibility Complex Class II Genes

2002 ◽  
Vol 70 (1) ◽  
pp. 380-388 ◽  
Author(s):  
Roman Reddy Ganta ◽  
Melinda J. Wilkerson ◽  
Chuanmin Cheng ◽  
Aaron M. Rokey ◽  
Stephen K. Chapes
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Macrophage Activation ◽  
Class Ii ◽  
Ehrlichia Chaffeensis ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Wild Type ◽  
Mhc Ii ◽  
Histocompatibility Complex

ABSTRACT Human monocytic ehrlichiosis is an emerging tick-borne disease caused by the rickettsia Ehrlichia chaffeensis. We investigated the impact of two genes that control macrophage and T-cell function on murine resistance to E. chaffeensis. Congenic pairs of wild-type and toll-like receptor 4 (tlr4)- or major histocompatibility complex class II (MHC-II)-deficient mice were used for these studies. Wild-type mice cleared the infection within 2 weeks, and the response included macrophage activation and the synthesis of E. chaffeensis-specific Th1-type immunoglobulin G response. The absence of a functional tlr4 gene depressed nitric oxide and interleukin 6 secretion by macrophages and resulted in short-term persistent infections for ≥30 days. In the absence of MHC-II alleles, E. chaffeensis infections persisted throughout the entire 3-month evaluation period. Together, these data suggest that macrophage activation and cell-mediated immunity, orchestrated by CD4+ T cells, are critical for conferring resistance to E. chaffeensis.

scholarly journals A Functionally Essential Domain of RFX5 Mediates Activation of Major Histocompatibility Complex Class II Promoters by Promoting Cooperative Binding between RFX and NF-Y

2000 ◽  
Vol 20 (10) ◽  
pp. 3364-3376 ◽  
Author(s):  
Jean Villard ◽  
Marie Peretti ◽  
Krzysztof Masternak ◽  
Emmanuèle Barras ◽  
Giuseppina Caretti ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Class Ii ◽  
Terminal Region ◽  
Cooperative Binding ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Rfx Complex

ABSTRACT Major histocompatibility complex class II (MHC-II) molecules occupy a pivotal position in the adaptive immune system, and correct regulation of their expression is therefore of critical importance for the control of the immune response. Several regulatory factors essential for the transcription of MHC-II genes have been identified by elucidation of the molecular defects responsible for MHC-II deficiency, a hereditary immunodeficiency disease characterized by regulatory defects abrogating MHC-II expression. Three of these factors, RFX5, RFXAP, and RFXANK, combine to form the RFX complex, a regulatory protein that binds to the X box DNA sequence present in all MHC-II promoters. In this study we have undertaken a dissection of the structure and function of RFX5, the largest subunit of the RFX complex. The results define two distinct domains serving two different essential functions. A highly conserved N-terminal region of RFX5 is required for its association with RFXANK and RFXAP, for assembly of the RFX complex in vivo and in vitro, and for binding of this complex to its X box target site in the MHC-II promoter. This N-terminal region is, however, not sufficient for activation of MHC-II expression. This requires an additional domain within the C-terminal region of RFX5. This C-terminal domain mediates cooperative binding between the RFX complex and NF-Y, a transcription factor binding to the Y box sequence of MHC-II promoters. This provides direct evidence that RFX5-mediated cooperative binding between RFX and NF-Y plays an essential role in the transcriptional activation of MHC-II genes.

scholarly journals Antigen Presentation by Dendritic Cells after Immunization with DNA Encoding a Major Histocompatibility Complex Class II–restricted Viral Epitope

1997 ◽  
Vol 186 (9) ◽  
pp. 1481-1486 ◽  
Author(s):  
Sofia Casares ◽  
Kayo Inaba ◽  
Teodor-Doru Brumeanu ◽  
Ralph M. Steinman ◽  
Constantin A. Bona
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Antigen Presentation ◽  
Class Ii ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Dna Encoding ◽  
Histocompatibility Complex

Intramuscular and intracutaneous immunization with naked DNA can vaccinate animals to the encoded proteins, but the underlying mechanisms of antigen presentation are unclear. We used DNA that encodes an A/PR/8/34 influenza peptide for CD4 T cells and that elicits protective antiviral immunity. DNA-transfected, cultured muscle cells released the influenza polypeptide, which then could be presented on the major histocompatibility complex class II molecules of dendritic cells. When DNA was injected into muscles or skin, and antigen-presenting cells were isolated from either the draining lymph nodes or the skin, dendritic, but not B, cells presented antigen to T cells and carried plasmid DNA. We suggest that the uptake of DNA and/or the protein expressed by dendritic cells triggers immune responses to DNA vaccines.

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