Th1/Th2 Differentiation and Cross-regulation

摘要

The T helper (Th) phenotypes, Th1/Th2, are acquired upon interaction of a naive T helper cell and an antigen presenting cell (APC). Naive T helper cells may differen- tiate into either phenotype, and the actual outcome is determined by the density and avidity of the antigenic determinants presented by the APC, and the APCs inherent costimulatory properties. Until recently it was thought that differentiation is further affected by cytokines. However, Murphy et al. (1996, J. Exp. Med, 183, 901) have demonstrated that the experimental results, formerly interpreted as Th1/Th2 differ- entiation, in effect comprise an observation of two consecutive processes.