Role of interleukin-4 in the licensing of dendritic cells for the induction of Th2 responses [B]

T helper type 2 (Th2) responses are crucial for defense against infections by helminths and are responsible for the development of allergic reactions that can lead to severe clinical disorders, such as asthma or anaphylaxis, and ultimately to death. The induction of Th2 responses requires a specific activation process, triggered by specialized dendritic cells (DCs), by which naive CD4+ Th0 cells acquire the capacity to produce Th2 cytokines. However, the mechanistic basis of the functional specialization enabling DCs for the initiation of Th2 responses has remained elusive. Here we show that interleukin-4 (IL-4), a cytokine produced by basophils, mast cells and Th2-polarized CD4+ T helper cells, exerting a crucial function during anti-helminths and allergic Th2 responses, has a key role in the licensing/conditioning of DCs for the induction of Th2 responses, by bloking their potential to produce Th1-driving cytokines, such as IL-12, IL-18 and IL-23. Microarray analyses (duplicates) were used to compared the transcriptional profile of monocyte-derived dendritic cells (moDCs) cultured with GM-CSF in the absence or presence of interleukin-4: IL4-moDCs versus C-moDCs.