Effect of Chinese herbal medicine extracts on cell-mediated immunity in a rat model of tuberculosis induced by multiple drug-resistant bacilli.

Drug-resistant Mycobacterium tuberculosis poses a major threat to public health. The present study aimed to investigate the effects of Radix Ranunculi Ternati, Radix Sophorae Flavescentis, Prunella Vulgaris L. and Stellera Chamaejasme L. extracts on cell‑mediated immunity in a rat model of tuberculosis (TB) induced by multiple drug-resistant bacilli. The bacterium was isolated from patients infected with pulmonary tuberculosis. The immunological response in humans following infection with Mycobacterium tuberculosis involves a number of cytokines, including IFN-γ and IFN-α, which are important for killing intracellular micro-organisms. T helper type 2 (Th2) cells express numerous cytokines, including IL-4 and IL-10, which mainly participate in humoral immunity and induce the phagocytosis of extracellular bacteria and parasites. In the present study, rats were infected with multiple drug-resistant TB (MDR-TB) in order to establish an MDR-TB model. Peripheral blood mononuclear cells (PBMCs) were isolated and cultivated, and the serum levels of IFN-γ, IL-4, IL-10 and IL-12 were examined by ELISA. The mRNA expression levels of certain cytokines in PBMCs were additionally detected using RT-PCR. The serum levels of IFN-γ in the Radix Ranunculi Ternati, Radix Sophorae Flavescentis, Prunella Vulgaris L. and Stellera Chamaejasme L. groups were 2.01±0.73, 1.92±0.56, 1.98±0.67 and 1.94±0.59 pg/ml; IL-4 levels were 6.01±1.46, 6.12±1.35, 6.47±1.46 and 6.15±1.44 pg/ml; IL-10 levels were 12.09±3.07, 12.45±4.01, 12.13±3.43 and 12.54±3.78 pg/ml; and IL-12 levels were 2.99±0.89, 2.75±0.84, 3.02±0.86 and 2.89±0.75 pg/ml, respectively. These differences were significant compared with the model group (P<0.05). RT-PCR analysis revealed a significant increase in the levels of IFN-γ and IL-12, and a significant decrease in the mRNA levels of IL-4 and IL-10 (P<0.05). These results indicated that the extracts of Radix Ranunculi Ternati, Radix Sophorae Flavescentis, Prunella Vulgaris L. and Stellera Chamaejasme L. are capable of enhancing cell‑mediated immunity in rats by upregulating the levels of genetic transcription. This may explain the observed therapeutic effect of Chinese herbal medicines in the treatment of MDR-TB.