Processing and Presentation of a Mycobacterial Antigen 85B Epitope by Murine Macrophages Is Dependent on the Phagosomal Acquisition of Vacuolar Proton ATPase and In Situ Activation of Cathepsin D
| Autor: | Lisa Y. Armitige, Mark B. Snuggs, Akhil Bidani, Subramanian Dhandayuthapani, Chinnaswamy Jagannath, Rachel A. Moulton, Robert L. Hunter, Christopher R. Singh |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Vacuolar Proton-Translocating ATPases
T cell Immunology Cathepsin D Biology complex mixtures Epitope Epitopes Interferon-gamma Mice Bacterial Proteins Antigen Western blot Phagosomes Phagosome maturation medicine Animals Immunology and Allergy Macrophage RNA Small Interfering Cells Cultured Phagosome Antigen Presentation Antigens Bacterial medicine.diagnostic_test Macrophages Mycobacterium tuberculosis Hydrogen-Ion Concentration Molecular biology Mice Inbred C57BL medicine.anatomical_structure Acids Acyltransferases |
| Zdroj: | The Journal of Immunology. 177:3250-3259 |
| ISSN: | 1550-6606 0022-1767 |
| DOI: | 10.4049/jimmunol.177.5.3250 |
| Popis: | Mycobacterium tuberculosis (strain H37Rv) and bacillus Calmette-Guérin (BCG) vaccine inhibit phagosome maturation in macrophages and their effect on processing, and presentation of a secreted Ag85 complex B protein, Ag85B, by mouse macrophages was analyzed. Macrophages were infected with GFP-expressing mycobacterial strains and analyzed for in situ localization of vacuolar proton ATPase (v-ATPase) and cathepsin D (Cat D) using Western blot analysis and immunofluorescence. H37Rv and BCG phagosomes excluded the v-ATPase and maintained neutral pH while the attenuated H37Ra strain acquired v-ATPase and acidified. Mycobacterial phagosomes acquired Cat D, although strains BCG and H37Rv phagosomes contained the inactive 46-kDa form, whereas H37Ra phagosomes had the active 30-kDa form. Infected macrophages were overlaid with a T cell hybridoma specific for an Ag85B epitope complexed with MHC class II. Coincident with active Cat D, H37Ra-infected macrophages presented the epitope to T cells inducing IL-2, whereas H37Rv- and BCG-infected macrophages were less efficient in IL-2 induction. Bafilomycin inhibited the induction of macrophage-induced IL-2 from T cells indicating that v-ATPase was essential for macrophage processing of Ag85B. Furthermore, the small interfering RNA interference of Cat D synthesis resulted in a marked decrease in the levels of macrophage-induced IL-2. Thus, a v-ATPase-dependent phagosomal activation of Cat D was required for the generation of an Ag85B epitope by macrophages. Reduced processing of Ag85B by H37Rv- and BCG-infected macrophages suggests that phagosome maturation arrest interferes with the efficient processing of Ags in macrophages. Because Ag85B is immunodominant, this state may lead to a decreased ability of the wild-type as well as the BCG vaccine to induce protective immunity. |
| Databáze: | OpenAIRE |
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