Levels of tumor necrosis factor-alpha (TNF-α) and Interferon gamma (IFN-γ) s During Tuberculosis treatment

Abstract

Cytokines play a major role in protection against Mycobacterium tuberculosis infection and

regulate the immune responses at a cellular level. A T helper 1 (Th1) cytokine interferon gamma

(IFN-γ) is one of the most important cytokines which activate the macrophages to produce tumor

necrosis factor-alpha (TNF-α). At physiological levels, TNF-α has anti-microbial activities

through the apoptotic effect. Excessive production of TNF-α have been implicated in

immunopathogenesis of tuberculosis. The aim of the present study was to determine Th1

cytokine profile in patients with tuberculosis to identify immunological marker for follow up of

the disease activity, and on the other hand, to study the outcome of anti-tuberculosis treatment.

To examine this, blood samples were collected at several intervals before and during the

treatment with anti-tuberculosis drugs. Levels of IFN-γ, TNF-α pre and during treatment using

commercial available enzyme-linked immune-sorbent assay (ELISA). Data were analyzed using

SPSS 20. Receiver Operating Characteristic (ROC) Curve analysis has been carried out to assess

their discriminative power and to determine cut-off values. Analysis has been carried out further

by calculating other measures of diagnostic test accuracy.The results showed that the levels of

TNF- were significantly increased in patients before and after the treatment than those in

control (p=0.001). Levels for IFN-γ were not statistically different between patients and controls

(p=0.351). A decrease in TNF-α levels dose not conflict with the finding that IFN-γ had highest

level in patients under treatment as the difference between those and newly diagnosed patients

was not statistically different. TNF-α can be used as a marker for TB severity, having that the

area under the curve (AUC) for TNF-α is .824 (95% CI: .737 - .912). For the chosen cut-off

level of 5pg/ml, it has a sensitivity of 85% and a lower specificity of 70%. TNF-α test is most

beneficial where prevalence is very low or very high.