Final answer:
The generation of TH1, TH2, and TH17 effector cells is regulated by cytokines secreted by APCs, which determine their differentiation and roles in the immune system. TH1, TH2, and TH17 cells have different functions in immune responses, while memory T cells ensure a rapid response to re-exposure of antigens.
Step-by-step explanation:
The development of TH1, TH2, and TH17 effector cells in the immune system is regulated by the exposure to specific cytokines secreted by antigen-presenting cells (APCs). This exposure to different cytokines directs the differentiation of activated helper T cells into various subsets, each with distinct functions in the adaptive and innate immune responses.
TH1 cells are known for their role in activating macrophages and cytotoxic T cells, which are essential for clearing intracellular pathogens. TH2 cells are crucial for the humoral immune response, stimulating B cells to produce antibodies. Contrastingly, TH17 cells provide defense against chronic mucocutaneous infections. Finally, memory T cells are generated to remember past infections for a faster response upon re-exposure.
Whether a TH1, TH2, or TH17 response develops is dependent on the nature of the invading pathogen and the subsequent cytokines that are secreted by cells of the innate immune system.