Final answer:
The transcription factor responsible for the induction of IL-4 in CD4 T helper 2 (TH2) cells is GATA3, which is a key player in the differentiation process directed by cytokines during T cell and APC interaction.
Step-by-step explanation:
The transcription factor that directs the induction of IL-4 in a CD4 T helper 2 (TH2) cell is GATA3. This process occurs when a CD4+ helper T cell binds to an MHC II-antigen complex on an antigen-presenting cell (APC), leading both the APC and the T cell to release cytokines. Specifically, the differentiation of activated helper T cells into either TH1 or TH2 subtypes is influenced by the cytokines they are exposed to during their interaction with APCs. In the case of TH2 cells, IL-4 production promotes the TH2 response, which is crucial for stimulating B cells to produce antibodies and combating extracellular pathogens.