181 Interferon-γ, Interferon-γ-Inducible Protein-10 and Tuberculin Skin Test Responses of Hiv-Positive and Hiv Negative Children in Northeast Brazil

Abstract

Background and aims: Detection of latent tuberculosis (TB) infection (LTBI) and provision of chemoprophylaxis is an important strategy for TB control, particularly for HIV-infected children. Assessing LTBI in this population is difficult because the tuberculin skin test (TST) is unreliable in immunosuppressed individuals. Interferon-γ release assays (QTF) have been recently used as complementary tools for the diagnosis of LTBI and Interferon-γ inducible protein-10 (IP-10) has been evaluated as a potential marker for detection of Mycobacterium tuberculosis infection. Our aim was to describe Interferon-γ, IP-10 and TST responses in HIV-positive and negative children in Northeast Brazil. Methods: TST, Interferon-γ and IP-10 responses were evaluated in HIV-positive and HIV-negative children with known contact with adults with TB, a previous or current diagnosis of active TB and controls with no history of TB contact or disease. Results: 41 HIV-positive and 56 HIV-negative children were enrolled. The concordance of TST and QTF was high amongst HIV-positive and HIV-negative children (k 0.85 and k 0.82 respectively). IP-10 concentrations were higher for both HIV-positive and negative children with positive QTF/TST agreement. HIV-positive children had lower IP-10 concentrations when compared with HIV-negative children. Interferon-γ and IP-10 concentrations did not significantly differ amongst HIV-positive children with active TB, TB Contact or controls. Among HIV-positive children, higher IP-10 concentrations were observed in children with higher CD4 counts. Conclusions: IP-10 concentrations had good correlation with positive QTF/TST agreement, reinforcing its potential role for the diagnosis of LTBI. Interferon-γ and IP-10 responses in HIV-positive children need to be further investigated.