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Tumour necrosis factor and interferon‐γ are required in host resistance against virulent Rhodococcus equi infection in mice: cytokine production depends on the virulence levels of R. equi
Author(s) -
Harue Kasuga-Aoki,
Shinji Takaı̈,
Yukako Sasaki,
Shiro Tsubaki,
Hiroo Madarame,
Akio Nakane
Publication year - 1999
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.1999.00657.x
Subject(s) - virulence , rhodococcus equi , microbiology and biotechnology , biology , virology , interferon gamma , tumor necrosis factor alpha , pathogen , virulence factor , cytokine , immunology , gene , biochemistry
Rhodococcus equi is a facultative intracellular bacterial pathogen that causes pneumonia in foals and immunosuppressed humans. There are at least three virulence levels of R. equi and these pathogenicities are associated, in mice, with the presence of virulence plasmids. This study focused on cytokine secretion, in mice, in the course of a primary infection with sublethal doses of R. equi strains of different virulence levels (virulent, intermediately virulent and avirulent). Tumour necrosis factor (TNF) and interferon‐γ (IFN‐γ), but not interleukin‐4 (IL‐4) and interleukin‐10 (IL‐10), were induced endogenously in mice in relation to the multiplication and clearance of virulent and intermediately virulent strains of R. equi . These cytokines were not detected in mice infected with avirulent R. equi . Deaths occurred among mice treated with monoclonal antibodies (mAbs) against either TNF or IFN‐γ prior to sublethal dose infection with virulent and intermediately virulent strains of R. equi , but not with avirulent R. equi . These results suggested that cytokine production depended largely on the virulence levels of R. equi : TNF and IFN‐γ were required early during infection with virulent R. equi to limit replication and clearance of bacteria within the organs, but they were not necessary for limiting infection with avirulent R. equi .