Figure 2.
Schematic diagram of nTreg development as it relates to T cell receptor (TCR) affinity and co-factors. The current model (A) of nTreg development indicates selection is mediated by high TCR affinity interactions with cognate peptide/MHC (pMHC) plus additional co-factors such as CD28-CD80/CD86 and IL-2 found in the medulla. A more recent model proposes nTreg development can occur in both the medulla and cortex based upon a balance between TCR/pMHC and multiple co-factors. In this model (B), nTregs that have high affinity for pMHC will need less co-factors such as the cytokines, TGFβ and IL-2 or co-stimulatory molecules, GITR and CD28.