Influence of HTLV-1 on the clinical, microbiologic and immunologic presentation of tuberculosis

BMC Infect Dis. 2012 Aug 28;12:199. doi: 10.1186/1471-2334-12-199.

Abstract

Background: HTLV-1 is associated with increased susceptibility to Mycobacterium tuberculosis infection and severity of tuberculosis. Although previous studies have shown that HTLV-1 infected individuals have a low frequency of positive tuberculin skin test (TST) and decreasing in lymphoproliferative responses compared to HTLV-1 uninfected persons, these studies were not performed in individuals with history of tuberculosis or evidence of M. tuberculosis infection. Therefore the reasons why HTLV-1 infection increases susceptibility to infection and severity of tuberculosis are not understood.The aim of this study was to evaluate how HTLV-1 may influence the clinical, bacteriologic and immunologic presentation of tuberculosis.

Methods: The study prospectively enrolled and followed 13 new cases of tuberculosis associated with HTLV-1 (cases) and 25 patients with tuberculosis without HTLV-1 infection (controls). Clinical findings, bacterial load in the sputum, x-rays, immunological response and death were compared in the two groups.

Results: There were no differences in the demographic, clinical and TST response between the two study groups. IFN-γ and TNF-α production was higher in unstimulated cultures of mononuclear cells of case than in control patients (p < 0.01). While there was no difference in IFN-γ production in PPD stimulated cultures, TNF-α levels were lower in cases than in controls (p = 0.01). There was no difference in the bacterial load among the groups but sputum smear microscopy results became negative faster in cases than in controls. Death only occurred in two co-infected patients.

Conclusion: While the increased susceptibility for tuberculosis infection in HTLV-1 infected subjects may be related to impairment in TNF-α production, the severity of tuberculosis in co-infected patients may be due to the enhancement of the Th1 inflammatory response, rather than in their decreased ability to control bacterial growth.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Bacterial Load
  • Female
  • HTLV-I Infections / complications*
  • Humans
  • Interferon-gamma / metabolism
  • Lung / diagnostic imaging
  • Lung / pathology
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / immunology*
  • Mycobacterium tuberculosis / pathogenicity*
  • Prospective Studies
  • Radiography, Thoracic
  • Sputum / microbiology
  • Survival Analysis
  • Th1 Cells / immunology
  • Tuberculosis / complications*
  • Tuberculosis / immunology
  • Tuberculosis / microbiology
  • Tuberculosis / pathology*
  • Tumor Necrosis Factor-alpha / metabolism
  • Young Adult

Substances

  • Tumor Necrosis Factor-alpha
  • Interferon-gamma