Figure 6.

Interleukin (IL)-21 enhances immune responses and inhibits Mycobacterium tuberculosis (Mtb) growth in infected Rag2 mice. Wild-type (WT) and Rag2 knockout (KO) mice (both C57BL/6) were infected with 50–100 colony-forming units (CFU) of H37Rv by aerosol. Few Rag2 KO mice received recombinant IL-21 or phosphate-buffered saline (PBS) through tail vein injection. One month after infection (A), the bacterial burden in the lungs was measured. Data are representative of 2 independent experiments. Five mice per group were used for each independent experiment. (B) Lung cells were prepared as mentioned under Methods. Expression of various cytokines and chemokines in the lung messenger ribonucleic acid was determined by quantitative real-time polymerase chain reaction. The mean values, P values, and standard errors are shown.