Th1/Th2 cytokine

T helper cells (Th) play a vital role in the adaptive immune system by suppressing or regulating immune responses. After Th actived, it will differentiate into T-helper 1 (Th1) or T-helper 2 (Th2) effector cells. These two subsets are characterized by their distinct cytokine expression pattern and the immune function they mediate. Th1 and Th2 cells each produce a specialized combination of cytokines that depends on type of pathogen that the helper T cell has recognized-some cytokines are more effective than others in the process of eliminating certain invaders. In general, TH1 cytokines play the role of immune killing, while Th2 cytokines play the role of immune protection. Th1/Th2 paradigm provides rationale for developing new vaccines against infectious diseases and novel strategies for the therapy of allergic and autoimmune disorders.