Dynamics of Th2 IL-4 and IL-10 Cytokines During the Treatment of Pulmonary Tuberculosis

Abstract

Tuberculosis is (TB), an infection caused by mycobacterium tuberculosis, responsible for high

morbidity and mortality worldwide. It is one of the major causes of morbidity and mortality in

Sudan. Cytokine profile determines clinical outcome of the disease and responses to treatment as

well. A T helper 2 (Th2) responses lead to release of IL-4, and IL-10, promoting B lymphocyte

activation leading to an antibody response and promoting an anti-inflammatory macrophage

response. Interleukin-4 (IL-4), an anti-inflammatory cytokine has been implicated to downregulate

IFN-γ, and thus has a harmful effect on TB patients. IL10 cytokine has the capacity to

inhibit Th1 activation and thus terminates cell mediated immune responses. The aim of the

present study was to determine Th2 cytokine profile in patients with tuberculosis to identify

immunological marker for follow up of the disease activity and to study the outcome of antituberculosis

treatment as well. To examine this, blood samples were collected from newly

diagnosed HIV negative pulmonary tuberculosis patients and from apparently healthy individuals

as controls following an informed consent. Blood samples were also collected at several intervals

during the treatment with anti-tuberculosis drugs. Levels of Th2 cytokines IL-4 and IL-10 were

measured pre and during treatment using commercial available enzyme-linked immune-sorbent

assay (ELISA). Data were analyzed using SPSS 20. The results showed that, the median serum

level of IL-4 was 20 and 35 pg/ml higher in new cases (untreated patients) and in patients under

treatment with oral anti-tuberculosis, respectively, compared with that of Controls (p=0.001).

Median levels of IL10 were similar in both controls and new cases groups (35pg/ml), but lower

in patients under treatment group (20pg/ml). Despite that, the difference in levels of IL-10 was

not statistically different between patients and controls (p=0.243). Increase in levels of IL-4

during treatment showed that Th2 immune responses still present and may indicate active disease

and thus IL4 cytokine may be a possible marker for the disease activity. Result showed that, IL-4

has the potential to be used as marker for TB severity (specificity=91%) having the area under

the curve AUC of 0.659.