Furthermore, concerning the connection between allergy development and balance in Th1 versus Th2 responses, miR-29 directly targets the TBX21 mRNA (also known as T-bet), the key transcription factor of Th1 cells (124), and miR-181-5p targets CD4, a co-receptor of the T cell receptor expressed on Th cells. This evidence concerns the gene TBX21 and allergic disease.