Is IP-10 an Accurate Marker for Detecting M. tuberculosis-Specific Response in HIV-Infected PersonsReport as inadecuate

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The suboptimal sensitivity of Interferon IFN-γ-based in-vitro assays, especially in immunocompromised individuals, emphasizes the need for alternative markers for diagnosing tuberculosis TB. The objective of this study was to evaluate whether interferon-inducible protein IP-10, monocyte chemotactic protein MCP-2 and interleukin IL-2 can be useful biomarkers for evaluating a specific response to RD1 antigens associated to active TB disease in HIV-infected individuals.

Methodology-Principal Findings

The study was carried out in India, the country with the highest TB burden in the world. Sixty-six HIV-infected individuals were prospectively enrolled, 28 with active-pulmonary-TB and 38 without. The whole blood assay based on RD1-selected peptides experimental test and QuantiFERON-TB Gold In tube QFT-IT was performed. Plasma was harvested at day-1-post-culture and soluble factors were evaluated by ELISA. The results indicate that by detecting IP-10, the sensitivity of the experimental test and QFT-antigen 75% and 85.7% respectively for active TB was higher compared to the same assays based on IFN-γ 42.9% and 60.7% respectively and was not influenced by the ability to respond to the mitogen. By detecting IP-10, the specificity of the experimental test and QFT-antigen 57.9% and 13.2% respectively for active TB was lower than what was reported for the same assays using IFN-γ-detection 78.9% and 68.4% respectively. On the other side, in vitro IL-2 and MCP-2 responses were not significantly associated with active TB.


HIV infection does not impair RD1-specific response detected by IP-10, while it significantly decreases IFN-γ-mediated responses. At the moment it is unclear whether higher detection is related to higher sensitivity or lower specificity of the assay. Further studies in high and low TB endemic countries are needed to elucidate this.

Author: Delia Goletti , Alamelu Raja, Basirudeen Syed Ahamed Kabeer, Camilla Rodrigues, Archana Sodha, Stefania Carrara, Guy Vernet, Chri



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