**Immune Phenotype and Functionality of** *Mtb***-Specific T-Cells in HIV**/**TB Co-Infected Patients on Antiretroviral Treatment**

**Lucy Mupfumi 1,2,\*, Cheleka A.M. Mpande 3, Tim Reid 3, Sikhulile Moyo 2,4, Sanghyuk S. Shin 5, Nicola Zetola 6,7, Tuelo Mogashoa 1, Rosemary M. Musonda 2,4, Ishmael Kasvosve 1, Thomas J. Scriba 3, Elisa Nemes 3,**† **and Simani Gaseitsiwe 2,4,\*,**†


Received: 21 December 2019; Accepted: 27 February 2020; Published: 2 March 2020

**Abstract:** The performance of host blood-based biomarkers for tuberculosis (TB) in HIV-infected patients on antiretroviral therapy (ART) has not been fully assessed. We evaluated the immune phenotype and functionality of antigen-specific T-cell responses in HIV positive (+) participants with TB (n = 12) compared to HIV negative (−) participants with either TB (n = 9) or latent TB infection (LTBI) (n = 9). We show that the cytokine profile of Mtb-specific CD4+ T-cells in participants with TB, regardless of HIV status, was predominantly single IFN-γ or dual IFN-γ/ TNF α. Whilst ESAT-6/CFP-10 responding T-cells were predominantly of an e ffector memory (CD27−CD45RA−CCR7−) profile, HIV-specific T-cells were mainly of a central (CD27+CD45RA−CCR7+) and transitional memory (CD27+CD45RA+/−CCR7−) phenotype on both CD4+ and CD8+ T-cells. Using receiving operating characteristic (ROC) curve analysis, co-expression of CD38 and HLA-DR on ESAT-6/CFP-10 responding total cytokine-producing CD4+ T-cells had a high sensitivity for discriminating HIV+TB (100%, 95% CI 70–100) and HIV−TB (100%, 95% CI 70–100) from latent TB with high specificity (100%, 95% CI 68–100 for HIV−TB) at a cut-o ff value of 5% and 13%, respectively. TB treatment reduced the proportion of *Mtb*-specific total cytokine+CD38+HLA-DR+ CD4+ T-cells only in HIV−TB (*p* = 0.001). Our results sugges<sup>t</sup> that co-expression of CD38 and HLA-DR on *Mtb*-specific CD4+ T-cells could serve as a TB diagnosis tool regardless of HIV status.

**Keywords:** immune activation; HLA-DR; CD38; treatment response
