Differential TCR signaling and the generation of memory T cells.

There are currently two models for the generation of memory T cells: 1) memory T cells arise directly from activated effector T cells that have reverted to the resting state via an unknown mechanism; and 2) memory T cells are generated directly from naive T cells, bypassing an effector stage. I discuss here how recent results on the activation and signaling requirements of naive vs memory CD4 T cells favor the second model and how differential signaling of naive T cells may direct their developmental outcome.