Therapeutic effect of interleukin-12 on murine infection with Mycobacterium tuberculosis through modulating Th1 and Th2 cytokine balance

OBJECTIVE: To study the effect of IL-12 on cytokines of murine infection with Mycobacterium tuberculosis. METHODS: 42 BALB/c mice infected with Mycobacterium tuberculosis were randomized into normal control (PBS) and IL-12 (n = 21) groups, treated with PBS or IL-12 respectively. Blood level of IFN-gamma, IL-4, and IL-10 were detected with ELISA method. The numbers of viable bacteria in organs were counted. Survival rate after treatment was investigated. RESULTS: In IL-12 group, none was dead. The numbers of viable bacteria in lung, liver and spleen were (227 +/- 107) x 10(5) cfu/ml, (4 +/- 3) x 10(5) cfu/ml and (1.5 +/- 0.5) x 10(5) cfu/ml respectively. INF-gamma (1,090 +/- 406) pg/ml. In PBS group, 8 mice were dead. The numbers of viable bacteria in lung, liver and spleen were (659 +/- 405) x 10(5) cfu/ml, (23 +/- 19) x 10(5) cfu/ml and (10.8 +/- 3.5) x 10(5) cfu/ml respectively. IFN-gamma (548 +/- 214) pg/ml. There was significant difference between those two groups. No change of the level of IL-4 in two groups. CONCLUSIONS: IL-12 induced IFN-gamma production, promoted development of Th1 cell responses, modulated Th1 and Th2 cytokine balance, suggesting that IL-12 enhance the host defense against the infection.