Blood levels of Mycobacterium tuberculosis (Mtb)antigen-triggered immune markers in people exposed to tuberculosis with regard to Mtb infection status and receipt of tuberculosis preventive therapy.

BACKGROUND

Interferon-γ release assays (IGRAs) for tuberculosis infection (TBI) cannot distinguish different stages of the TBI spectrum (including spontaneously cleared infection). We investigated patterns of Mtb-specific blood mediators in people with and without TBI during tuberculosis preventive therapy (TPT).

METHODS

Individuals with likelihood of recent Mtb exposure, aged 15-25 years, with valid IGRA results, in whom tuberculosis (TB) had been excluded, were included. Persons with TBI were sampled prior to TPT (IGRA + pre-treatment, n = 15) or after completion of TPT (IGRA + post-treatment, n = 15). Five persons without TBI were included as controls (IGRA-). Levels of 40 mediators related to TB immune control in blood incubated with Mtb antigens in the QuantiFERON-TB Plus® kit were assessed with electrochemiluminescence assay and compared between participant categories.

RESULTS

The concentration of 10 mediators (GM-CSF, interferon-γ, IL-2, I-TAC, IL-12, IP-10, I-309, MCP-2, MIG, and VEGF) significantly differed between IGRA + pre-treatment and IGRA-. A non-significant trend in levels of these markers was observed between IGRA + pre-treatment, IGRA + post-treatment and IGRA-. Based on these mediators two clusters were identified: A (n = 16), including 5 IGRA-, 4 IGRA + pre-treatment, 7 IGRA + post-treatment and B (n = 19), including 11 IGRA + pre-treatment and 8 IGRA + post-treatment.

CONCLUSION

Plasma levels of several Mtb-triggered mediators differed with regard to TBI status among persons recently exposed to TB, suggesting the potential for alternative markers to assess TBI status. Longitudinal analysis of these mediators during TPT is warranted to explore whether these markers can be used to assess likelihood of persistence of viable bacilli in Mtb-exposed individuals.

CLINICALTRIALS

govID:NCT05621343.