Dendritic cells infected with Mycobacterium bovis bacillus Calmette Guerin activate CD8(+) T cells with specificity for a novel mycobacterial epitope.
Although CD4(+) T cells are essential for protective immunity against Mycobacterium tuberculosis infection, recent reports indicate that CD8(+) T cells may also play a critical role in the control of this infection. However, the epitope specificity and the mechanisms of activation of mycobacteria-reactive CD8(+) T cells are poorly characterized. In order to study the CD8(+) T cell responses to the model mycobacterial antigen, MPT64, we used recombinant vaccinia virus expressing MPT64 (VVWR-64) and a panel of MPT64-derived peptides to establish that the peptide MPT64(190-198) contains an H-2D(b)-restricted CD8(+) T cell epitope. A cytotoxic T lymphocyte response to this peptide could be demonstrated in M. bovis bacillus Calmette Guerin (BCG)-infected mice following repeated in vitro stimulation. When bone marrow-derived dendritic cells (DC) were infected with BCG, the expression of MHC class I molecules by DC was up-regulated in parallel with MHC class II and B7-2, whereas CD1d expression level was not modified. Moreover, BCG-infected DC activated MPT64(190-198)-specific CD8(+) T cells to secrete IFN-gamma, although with a lower efficacy than VVWR-64-infected DC. The production of IFN-gamma by MPT64(190-198)-specific CD8(+) T cells was inhibited by antibodies to MHC class I, but not to CD1d. These data suggest that mycobacteria-specific CD8(+) T cells are primed during infection. Therefore, anti-mycobacterial vaccine strategies targeting the activation of specific CD8(+) T cells by DC may have improved protective efficacy.
Feng
C G
CG
Centenary Institute of Cancer Medicine and Cell Biology, Locked Bag No. 6, Newtown, NSW 2042, Australia.
Demangel
C
C
Kamath
A T
AT
Macdonald
M
M
Britton
W J
WJ
D000818:Animals; D000942:Antigens, Bacterial / Q000096:biosynthesis / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003713:Dendritic Cells / Q000382:microbiology*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005260:Female; D005822:Genetic Vectors; D006183:H-2 Antigens / Q000276:immunology; D064532:Histocompatibility Antigen H-2D; D007114:Immunization; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D009163:Mycobacterium bovis / Q000276:immunology*; D010455:Peptides / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014616:Vaccinia virus
D000942:Antigens, Bacterial; D018984:Epitopes, T-Lymphocyte; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D010455:Peptides; D011994:Recombinant Proteins