Current model of CD8+ T-cell central and effector memory generation for mouse and human T cells. This model of T-cell differentiation is also known as the “linear” or “developmental” model. Unlike previous models that proposed that T effector cells gave rise to memory cells, the developmental model indicates that less differentiated memory cell types that express CD62L give rise to effector cells, and not vice versa. APC, antigen-presenting cell; TCM, central memory T cell; TEFF, effector T cell; TEM, effector memory T cell; TN, naive T cell; TSCM, T memory stem cell. Figure prepared by Dr Nicholas P. Restifo.