Inductive microRNA‐21 impairs anti‐mycobacterial responses by targeting IL‐12 and Bcl‐2

miR‐21 has been shown to regulate multiple mRNAs and cause tumor progression and metastasis. However, whether miR‐21‐mediated posttranscriptional regulation is involved in antigen presentation and anti‐mycobacterial responses remains unclear. Here, we report that miR‐21 can be induced after Bacillus Calmette‐Guerin (BCG) vaccination by NF‐kB activation. miR‐21 suppressed IL‐12 production by targeting IL‐12p35, which impaired anti‐mycobacterial T cell responses both in vitro and in vivo. Additionally, miR‐21 also promoted dendritic cell (DC) apoptosis by targeting Bcl‐2. Therefore, miR‐21 may potentially be involved in fine‐tuning of the anti‐mycobacterial Th1 response and in regulating the efficacy of BCG vaccination.