Bifunctional T-Cell-Derived Cytokines for the Diagnosis of Tuberculosis and Treatment Monitoring

Abstract

Background: Diagnosis and treatment monitoring of patients with tuberculosis remain challenging. Objective: We have evaluated whether Mycobacterium-specific interferon (IFN)-γ and interleukin (IL)-2 bifunctional cytokine immune response assays improve the diagnosis of and correlate to treatment response in pulmonary tuberculosis. Methods: Early secretory antigenic target (ESAT)6/culture filtrate protein 10 (CFP10), microsomal triglyceride transfer protein 65 (MTP65) and the purified protein derivative (PPD) tuberculin-specific immune profiles were investigated in peripheral blood mononuclear cells from 19 patients with culture-confirmed tuberculosis and 23 healthy community controls (HCCs; 82.6% with latent M. tuberculosis infection) using a novel fluorescence-based dual-colour enzyme-linked immunospot (EliSpot) technology (FluoroSpot). Results: The frequency of ESAT6/CFP10-induced IFN-γ+IL-2- producing cells was elevated (p < 0.001), whereas the percentages of specific IFN-γ-IL-2+ (p = 0.002) and IFN-γ+IL-2+ double producing cells (p = 0.037) were diminished in tuberculosis patients in comparison to HCCs. A 3-host marker model using a combination of those IFN-γ and IL-2 single-cell responses showed 93.8% sensitivity and 77.8% specificity for tuberculosis. During tuberculosis treatment, the PPD-induced immune responses shifted from an IFN-γ+IL-2- dominated profile towards a balance of IFN-γ-IL-2+ and IFN-γ+IL-2+ double producing cells (all p ≤ 0.05). Conclusions: The addition of antigen-specific IL-2 production to IFN-γ responses by EliSpot in IFN-γ release assays increases diagnostic sensitivity for active tuberculosis.

Utility of Th1-cell immune responses for distinguishing active tuberculosis from non-active tuberculosis: A case-control study

“…Similar to this study, Chesov’s study also showed no significant difference between patients with previous TB and patients with LTBI. Essone PN et al[19] in South Africa also found that frequencies of single IFN-γ secreting T cells were higher in the TB group than in the healthy control group (P = 0.062).…”

Combined Use of Mycobacterium tuberculosis–Specific CD4 and CD8 T-Cell Responses Is a Powerful Diagnostic Tool of Active Tuberculosis

“…In this regard, recent studies have identified other immunological markers that may discriminate between active and latent tuberculosis. The new markers include IFN-γ and IL-2 single T-cell responses [ 19 ] and the decrease of CD27 expression in Mtb -specific CD4 T cells [ 20 ]. However, the former markers were analyzed in a very small number (<20) of patients, and the latter has been shown to discriminate between active and chronic tuberculosis only in pediatric patients [ 21 ] and to be associated with persistent active tuberculosis in adult patients [ 22 ].…”

Assessment of treatment response in tuberculosis

“…Successful ATT decreases mycobacterial load and restores peripheral T cell proliferation capacity and some studies have shown that polyfunctional T cells and MTB-specific cells T cells with single expression of IL-2 predominate [71]. Some subsequent studies have failed to conclusively demonstrate that polyfunctional MTB-specific T cells are definitively associated with successfully treated TB, whilst others assert that IL-2 + single producing and/or IL-2 + and IFN-γ + double producing MTB-specific T cell frequency is associated with successful treatment [72-74]. Multiple studies have shown a decline during therapy in the proportion of unstimulated and MTB antigen- stimulated regulatory T cell subsets (CD4 + CD25 high CD127 low , CD4 + CD25 + FoxP3 + ,CD4 + CD25 high CD147 ++ and CD4 + CD25 high CD127 low CD161 + T regs ) in both pulmonary and extrapulmonary TB [75].…”