Sifting through CD8 + T Cell Memory.

In this issue of Immunity, Gerlach et al. (2016) describe three distinct memory CD8+ T cell subsets based upon expression of the fractalkine receptor CX3CR1. Their findings revise the paradigm of effector and central memory T cells by revealing a subset of CD8+ memory T cells defined by intermediate levels of expression of CX3CR1 that conducts tissue surveillance.