Alternative Quantiferon cytokines for diagnosis of children with active tuberculosis and HIV co-infection in Ghana

Abstract

IFN-γ release assays (IGRAs) often present false-negative or indeterminate results in children with tuberculosis. HIV co-infection may contribute to decreased sensitivity of IGRAs by impairing T-cell IFN-γ expression. Measurement of alternative cytokines in QuantiFERON (QFT) supernatants can circumvent the IFN-γ-dependency and may improve QFT sensitivity. We aimed to identify additional cytokines from QFT supernatants for detection of Mycobacterium tuberculosis infection in children with tuberculosis and HIV co-infection from Ghana. Concentrations of 18 cytokines in QFT supernatants from children (0-16 years) with tuberculosis concomitantly infected with HIV (n = 25) or without HIV (n = 24) from Ghana were measured using cytometric bead array (CBA). 29% of the children showed positive IFN-γ test results, and five cytokines, i.e., IL-6, IL-21, TNF-α, IL-1α and IP-10, detected M. tuberculosis infection with comparable or, for IL-6, with significantly higher sensitivity (59%). Increased age and HIV co-infection were associated with decreased cytokine induction, and especially IL-21 and IP-10 were less prevalent in HIV co-infected children with tuberculosis. Combined cytokine analyses increased proportions of positive tests, and a four-cytokine subset (i.e., IL-6, IL-21, IFN-γ, IL-1α) predicted 78% of the children with tuberculosis correctly. Combined evaluation of IFN-γ and alternative cytokines improved IGRA-sensitivity in children with tuberculosis.

Two-Hit in vitro T-Cell Stimulation Detects Mycobacterium tuberculosis Infection in QuantiFERON Negative Tuberculosis Patients and Healthy Contacts From Ghana

“…QFT results were negative or indeterminate for the majority of tuberculosis patients and healthy contacts. This outcome confirmed own previous studies that showed low sensitivity of QFT tests for detection of Mtb infection in children with tuberculosis from Ghana (6). In contrast, a parallel study in children with tuberculosis and LTBI from Germany showed almost optimal sensitivity of the QFT (7).…”

“…But by implication, these studies excluded tuberculosis patients and HCs that were false negative in QFT/IGRA. Since previous studies clearly demonstrated that also IFN-γ negative CD4 + T cells producing alternative cytokines contribute to immunity against Mtb (6, 30), we hypothesize that negative QFT/IGRA results do not preclude Mtb infection.…”

“…A previously described algorithm for the interpretation of IFN-γ values based on manufacturer's criteria was used for comparison of QFT (Table S1). These criteria have been adjusted for evaluation of QFT in-vitro results (Table S2) (6). QFT includes two tubes (TB1, TB2 according to manufacturer's nomenclature) containing Mtb antigens optimized for CD4 + and CD8 + T-cell response, respectively.…”

“…IGRAs can be assessed faster (i.e., after 16h) with TST comparable sensitivity but higher specificity especially in BCG vaccinated individuals (4, 5). Own previous studies showed that QFT sensitivity varies markedly between children with tuberculosis from different regions, being high in children with tuberculosis from Germany and alarmingly low in children from Ghana (6, 7). The usage of few selected antigens may contribute to population-dependent differences in QFT sensitivity due to differential MHC or exposure background.…”

Identification and validation of host biomarkers for leprosy: A step forward to establish point-of-care tests

“…Interferon-gamma (IFN-γ) release assays (IGRAs) are a standard diagnostic tool in high-income countries with low incidence rates. However, limited sensitivity of IGRAs in young children and immune-compromised individuals as well as potentially in some high-endemic countries highlight the need for additional assays and/or more complex biomarker signatures [1,2].…”