[Cytokine gene expression in Th1 and Th2: its molecular mechanism and clinical implication].

Activation of helper T-cells mediated by the T-cell receptor induces a series of biochemical events. Among them, both the activation of PKC/Ras- and CaM/CN-mediated pathways play a central role in the signal transduction of cytokine gene induction. Cytokines produced by non-transformed Th1 and Th2 clones were classified into three groups, based on their signal requirement patterns for their expression. Closer examination using various stimulation conditions suggested that the balance between the activities of the two signaling pathways contributes to cytokine expression. Th1 and Th2 effector functions and their development are attributable to their coordinated and differential expression of cytokines. Clarification of the mechanisms of Th1/Th2 differentiation should lead to rational strategies for manipulating pathological immune responses.