Increased levels of immunological markers in the respiratory tract but not in serum correlate with active pulmonary mycobacterial infection in mice

John Arko-Mensah, M. J. Rahman, E. Julián, G. Horner, M. Singh, C. Fernández

Research output: Contribution to journalArticleResearchpeer-review

4 Citations (Scopus)

Abstract

Immunological tests for the diagnosis of tuberculosis (TB) have relied mostly on detection of immune markers in serum or release of cytokines by mononuclear cells in.vitro . These tests, although useful, sometimes fail to discriminate between active infection and contact with mycobacteria or vaccination. TB is primarily a disease of the lung, and therefore identification of immunological markers in the respiratory tract will be more likely to reflect the infection status or disease activity. In this study, it is demonstrated that active infection of mice with Mycobacterium bovis bacille Calmette-Guérin (BCG), but not exposure to heat-killed BCG, induced production of interleukin-12 (IL-12), interferon-γ (IFN-γ) or soluble tumour necrosis factor receptors (sTNFRs) locally in the lungs, as detected in bronchoalveolar lavage (BAL) fluid. There was a strong correlation between bacterial growth in the lung and levels of sTNFRs, and to some extent IL-12 and IFN-γ, in BAL fluid. Furthermore, sTNFR levels increased significantly in BAL fluid after reactivation of controlled infection with dexamethasone, and this correlated with increased bacterial growth in the lungs. Finally, infection, but not exposure to non-replicating mycobacteria, induced specific IgG and IgA in BAL fluid. Elevated levels of all biomarkers measured were also detected in the serum, but correlation with infection was not as clear as in the case of BAL fluid. Taken together, the detection of sTNFRs and mycobacterium-specific antibodies, especially IgA, locally in the lungs could be used as immunological markers for the diagnosis of TB. © 2009 The Authors Journal compilation © 2009 European Society of Clinical Microbiology and Infectious Diseases.
Original languageEnglish
Pages (from-to)777-786
JournalClinical Microbiology and Infection
Volume15
DOIs
Publication statusPublished - 1 Jan 2009

Keywords

  • Antibodies
  • Cytokine receptors
  • Cytokines
  • Lung infection
  • Mycobacterial infection

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