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Vaccination of brushtail possums, Trichosurus vulpecula , with Bacille Calmette–Guerin induces T lymphocytes that reduce Mycobacterium bovis replication in alveolar macrophages via a contact‐dependent/nitric oxide‐independent mechanism
Author(s) -
Denis Michel,
Wedlock D Neil,
Buddle Bryce M
Publication year - 2005
Publication title -
immunology and cell biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0818-9641
DOI - 10.1111/j.1440-1711.2005.01309.x
Subject(s) - vaccination , mycobacterium bovis , nitric oxide , microbiology and biotechnology , biology , immunology , virology , medicine , tuberculosis , mycobacterium tuberculosis , pathology , endocrinology
The permissiveness of alveolar macrophages from brushtail possums for the replication of Mycobacterium bovis was examined. Mycobacterium bovis replication was indirectly measured by assessing bacterial metabolism via the incorporation of [3‐H]‐uracil by bacilli released from lysed macrophages previously infected with mycobacteria. Alveolar macrophages allowed substantial replication of virulent M. bovis , in contrast to Bacille Calmette–Guerin (BCG) Pasteur, which replicated poorly. The addition of crude lymphokines enhanced the metabolic activity of phagocytosed M. bovis in possum macrophages. Possum lymphokines enhanced the ability of possum macrophages to generate reactive oxygen intermediates, measured by the reduction of nitroblue tetrazolium, which is indicative of an activation process. Similarly, the addition of recombinant possum TNF‐α enhanced the permissiveness of alveolar macrophages for M. bovis . In contrast to mouse peritoneal macrophages, possum alveolar macrophages did not release significant levels of nitric oxide (NO) after stimulation with M. bovis and/or lymphokines. However, the uptake of virulent M. bovis by possum macrophages was associated with an enhanced ability of cells to release TNF‐α, whereas very low levels of TNF‐α were released after infection with BCG. The addition of a selective inhibitor of inducible NO synthase had no impact on the replication of M. bovis or BCG in possum macrophages in the presence or absence of lymphokines. Co‐culturing infected possum alveolar macrophages with autologous blood mononuclear cells from BCG‐vaccinated possums led to a significant decrease in the metabolic activity of intracellular M. bovis . This effect was contact dependent and NO independent and was mediated by a population of CD3 + cells. In addition, adding scavengers of reactive oxygen intermediates did not abrogate this phenomenon.