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Infect. Immun., 01 1998, 98-106, Vol 66, No. 1
KN Balaji and WH Boom
Mycobacterium tuberculosis readily activates both CD4+ and Vdelta2+
gammadelta T cells. Despite similarity in function, these T-cell subsets
differ in the antigens they recognize and the manners in which these
antigens are presented by M. tuberculosis-infected monocytes. We
investigated mechanisms of antigen processing of M. tuberculosis antigens
to human CD4 and gammadelta T cells by monocytes. Initial uptake of M.
tuberculosis bacilli and subsequent processing were required for efficient
presentation not only to CD4 T cells but also to Vdelta2+ gammadelta T
cells. For gammadelta T cells, recognition of M. tuberculosis-infected
monocytes was dependent on Vdelta2+ T-cell- receptor expression.
Recognition of M. tuberculosis antigens by CD4+ T cells was restricted by
the class II major histocompatibility complex molecule HLA-DR. Processing
of M. tuberculosis bacilli for Vdelta2+ gammadelta T cells was inhibitable
by Brefeldin A, whereas processing of soluble mycobacterial antigens for
gammadelta T cells was not sensitive to Brefeldin A. Processing of M.
tuberculosis bacilli for CD4+ T cells was unaffected by Brefeldin A.
Lysosomotropic agents such as chloroquine and ammonium chloride did not
affect the processing of M. tuberculosis bacilli for CD4+ and gammadelta T
cells. In contrast, both inhibitors blocked processing of soluble
mycobacterial antigens for CD4+ T cells. Chloroquine and ammonium chloride
insensitivity of processing of M. tuberculosis bacilli was not dependent on
the viability of the bacteria, since processing of both formaldehyde-fixed
dead bacteria and mycobacterial antigens covalently coupled to latex beads
was chloroquine insensitive. Thus, the manner in which mycobacterial
antigens were taken up by monocytes (particulate versus soluble) influenced
the antigen processing pathway for CD4+ and gammadelta T cells.
Copyright © 1998, American Society for Microbiology
Processing of Mycobacterium tuberculosis bacilli by human monocytes for CD4+ alphabeta and gammadelta T cells: role of particulate antigen
Department of Medicine, Case Western Reserve University and University Hospitals of Cleveland, Ohio 44106-4984, USA.
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