Fig. 2.

Setting the threshold for Th1 polarization. a Through the expression of miR-29a/b, T cells are finely balanced in the Th1-Th2 cell fate decision. This fine balance allows external microenvironmental factors to influence the cell fate decision, allowing the adaptive immune response to be highly responsive to the context of infection. b In the absence of miR-29a/b, IFNγ, Eomes and T-bet are derepressed, allowing stochastic effects to drive the cell fate decision towards the Th1 fate. This induction of a strong default reduces the capacity of the undifferentiated T cell to respond to appropriate microenvironmental cues, resulting in a less context-dependent immune response