In vitro QuantiFERON-TB gold antigen specific interleukin-1beta to diagnose TB among HIV-positive subjects.
Prabhavathi, M.; Basirudeen, S.A.K.; Anbarasu, D.; Raja, A.
Tuberculosis; 2016; 96; 27-30.
Background: The recently introduced IFN- g release assay (IGRA) has been reported to improve the diagnosis of TB. However, IGRA has suboptimal sensitivity to diagnose TB among HIV co-infected subjects. Apart from IFN- g , the pro inflammatory cytokines such as Interleukin-1beta (IL-1 b ), Tumor necrosis factor-alpha (TNF- a ), IL-2, IL-6, IL-8 and IL-12 are also play a major role in mycobacterial infections. This study aimed to analyze these cytokines for detecting active TB among HIV sero positive subjects.
Materials and methods: We had prospectively enrolled 53 HIV positive subjects and 55 HIV-TB co-infected patients from India . IGRA was performed by using QuantiFERON TB-Gold In tube (QFT-GIT) method. TB antigen specific IL-1 b , TNF- a , IL-2, IL-6, IL-8 and IL-12 levels were evaluated by ELISA in plasma harvested from QFT-GIT tubes.
Results and conclusion: The TB antigen specific IL-1 b levels were significantly elevated in HIV-TB co-infected patients compared to HIV positive subjects (p = 0.0004). The specificity of both IL-1 b (50.94%) and QFT-GIT (52.83%) remained similar in HIV positive subjects (p = 0.24). However, IL-1b had shown higher sensitivity (72.73%) than QFT-GIT (54.55%) to diagnose TB among HIV co-infected patients. Moreover, in culture test positive HIV-TB patients, antigen specific IL-1 b exhibited sensitivity of 84.21%; whereas QFT-GIT exhibited only 57.89% sensitivity. Unlike IFN- g (the read out marker of QFT-GIT), antigen specific IL-1 b levels were not influenced by low CD4 counts. The other cytokine levels were not significantly differ between the 2 groups. From this study we concluded that TB antigen specific IL-1 b may be an additional biomarker for active TB diagnosis among HIV positive subjects.
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