Abstract
Background: Identification and treatment of LTBI in HIV-positive individuals is one of the main recommendations of WHO. New IFN-γ release assays (IGRAs) are based on MTB-specific T-cell responses which are impaired in HIV/AIDS pts due to decreased numbers and function of CD4+/CD8+ T cells.
Aim: To study the influence of CD4+ and CD8+ T-cell counts on IGRA results in HIV/AIDS pts.
Matherials and methods: QuantiFERON-TB Gold In-Tube (QFT-GIT) (Cellestis, Australia) and T-SPOT.TB (SPOT) (Oxford Immunotec, UK) tests were performed according to manufacturers' instructions. CD4+/CD8+ T-cell counts were determined by flowcytometry (BD, FACSCanto II). Spearman correlation and t-test were used for statistical analysis. All pts provided written informed consent.
Results: From January 2010 to January 2011, 105 (62% males) (18-66 yrs) HIV-infected individuals in different stages of progression were recruited. The mean CD4+ and CD8+ count was 448 cells/μl (2–1731) and 1000 cells/μl (74-3871) respectively. 24/105 pts were positive in both IGRAs. In all 24 pts with positive IGRA results MTB-specific and Mitogen-induced IFN-γ production did not correlate with absolute CD4+/CD8+ T-cell counts (p>0.05). Mean values of CD4+/CD8+ T cells in pts with indeterminate results were insignificantly lower than in pts with negative and positive results in both IGRAs (p>0.05).
Conclusions: Our data demonstrate that TB antigen-specific immune responses can be detected in HIV/AIDS pts with low CD4+ and CD8+ T-cell counts using IGRAs. Both QFT-GIT and SPOT assays are useful immunodiagnostic tools in immunocompromised HIV pts.
Acknowledgements: This work was supported by the Ministry of Health, Republic of Bulgaria.
- © 2011 ERS