Figure 15: Late Treg cell plasticity. Multiple reports indicate that inducible Treg cells can readily switch to IL-17-producing cells upon with stimulation by inflammatory cytokines. Tregs stimulated with IL-6 and IL-21 can be induced to express IL-17. Under these conditions expression of FoxP3 is down-regulated. These findings indicate that mature Treg cells can be subverted to Th17-like cells after commitment to the FoxP3 transcriptional program. There is, at present, no evidence that the reciprocal conversion of Th17 cells towards a Treg cell phenotype occurs.