Diminished plasma levels of common ?-chain cytokines in pulmonary tuberculosis and reversal following treatment.

Kumar, N.P.; Banurekha, V.V.; Nair, D.; Babu, S .

PLoS One; 2017; 12; e0176495.

Abstract: Background: The immune response to tuberculosis (TB) is T cell dependent. T cells are the major facilitators of protection and effector functions with CD4 + T cells being the most important players, followed by CD8 + T cells. The common ?-chain cytokines IL-2, IL-7, IL-15, and IL-21 play a vital role in peripheral T cell growth and survival. However, the role of common ?-chain cytokines in pulmonary TB (PTB) is poorly understood.

Aim and methods: To examine the association of circulating common ?-chain cytokines with TB disease or infection, we examined the systemic levels of IL-2, IL-7, IL-15, and IL-21 in individuals with PTB, latent TB (LTB) or no TB infection (NTB). We also examined the levels of these cytokines in PTB individuals before and after anti-tuberculosis treatment.

Results: Circulating levels of IL-2, IL-7 and IL-21 were significantly diminished in PTB compared to LTB or NTB individuals. Moreover, TB antigen stimulated whole blood also exhibited diminished levels of common ?-chain cytokines in PTB compared to LTB or NTB individuals. The plasma levels of common ?-chain cytokines exhibited no significant association with the severity or extent of TB disease or with bacterial burdens. However, upon standard anti-TB treatment, both the systemic as well as the TB antigen stimulated levels of IL-2, IL-7 and IL-21 were significantly increased in PTB individuals.

Conclusion: Therefore our data demonstrate that diminished levels of common ?-chain cytokines are a common characteristic of PTB and potentially highlight the importance of boosting these responses to improve treatment outcomes.

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