Investigating Cellular Quiescence of T Lymphocytes and Antigen-Induced Exit from Quiescence

Naive T cells are in a quiescent state under homeostasis but respond to antigen stimulation by exiting from quiescence and entering the cell cycle. Appropriate regulation of quiescence is crucial for maintaining T cell homeostasis at steady state and initiating proper T cell responses to antigen stimulation. Emerging evidence indicates that signaling by mechanistic target of rapamycin (mTOR) plays a central role in the control of T cell quiescence and antigen-induced exit from quiescence through coordinating immune signals, cellular metabolic programs, and cell cycle machinery. The mTOR-dependent regulation of quiescence has also been implicated in the differentiation and function of memory T cells. In this chapter, we describe techniques to assess quiescent state of naive T cells under steady state and exit from quiescence upon TCR stimulation.