Evaluation of Tuberculosis Activity in Patients with Anthracofibrosis by Use of Serum Levels of IL-2 sRα, IFN-γ and TBGL (Tuberculous Glycolipid) Antibody

Abstract

Background: Anthracofibrosis, a descriptive term for multiple black pigmentation with fibrosis on bronchoscopic examination, has a close relationship with active tuberculosis (TB). However, TB activity is determined in the later stage by the TB culture results in some cases of anthracofibrosis. Therefore, it is necessary to identify early markers of TB activity in anthracofibrosis. There have been several reports investigating the serum levels of IL-2 sRα, IFN-γ and TBGL antibody for the evaluation of TB activity. In the present study, we tried to measure the above mentioned serologic markers for the evaluation of TB activity in patients with anthracofibrosis. Methods: Anthracofibrosis was defined when there was deep pigmentation (in more than two lobar bronchi) and fibrotic stenosis of the bronchi on bronchoscopic examination. The serum of patients with anthracofibrosis was collected and stored under refrigeration before the start of anti-TB medication. The serum of healthy volunteers (N=16), patients with active TB prior to (N=22), and after (N=13), 6 month-medication was also collected and stored. Serum IL-2 sRα and IFN-γ were measured with ELISA kit (R&D system, USA) and serum TBGL antibody was measured with TBGL EIA kit (Kyowa Inc, Japan). Results: Serum levels of IL-2 sRa in healthy volunteers, active TB patients before and after medication, and patients with anthracofibrosis were 640±174, 1,611±2,423, 953+-562, and 863±401 pg/ml, respectively. The serum IFN-γ levels were 0, 8.16±17.34, 0.70±2.53, and 2.33±6.67 pg/ml, and TBGL antibody levels were 0.83±0.80, 5.91±6.71, 6.86±6.85, and 3.22±2.59 U/ml, respectively. The serum level of TBGL antibody was lower than that of other groups (p<0.05). There was no significant difference of serum IL-2 sRa and IFN-γ levels among the four groups. Conclusion: The serum levels of IL-2 sRα, IFN-γ and TBGL antibody were not useful in the evaluation of TB activity in patients with anthracofibrosis. More useful ways need to be developed for the differentiation of active TB in patients with anthracofibrosis.