Fig. 3

Differentiation of naïve Th cells into Th2 cells. The T cell receptor (TCR) is triggered by the specific recognition of allergenic peptides presented by MHC molecules (MHC II) (event 1). Even in the absence of TCR triggering, the co-stimulatory and co-inhibitory receptors on the T cells direct the T cell polarization and determine the T cell fate (events 2). The upregulation of transcription factor GATA-3 (event 3) is essential in the polarization towards Th2 since it suppresses Th1 and Th17 polarizing events (event 4) while promoting the IL-4, IL-5 and IL-13 gene translation (event 5), the so called keystones of the Th2 response. Cytokines produced by these polarized Th2 cells, including IL-2 and IL-4 can self-amplify the differentiation process (events 6). ILs interleukins, Rec receptors, CDs cluster of differentiation, TF transcription factors