RT Journal Article SR Electronic T1 Cutting Edge: Rapid In Vivo Killing by Memory CD8 T Cells JF The Journal of Immunology JO J. Immunol. FD American Association of Immunologists SP 27 OP 31 DO 10.4049/jimmunol.171.1.27 VO 171 IS 1 A1 Barber, Daniel L. A1 Wherry, E. John A1 Ahmed, Rafi YR 2003 UL http://www.jimmunol.org/content/171/1/27.abstract AB In this study, we examined the cytotoxic activity of effector and memory CD8 T cells in vivo. At the peak of the CTL response following an acute lymphocytic choriomeningitis virus infection, effector CD8 T cells exhibited extremely rapid killing and started to eliminate adoptively transferred target cells within 15 min by a perforin-dependent mechanism. Although resting memory CD8 T cells are poorly cytolytic by in vitro 51Cr release assays, there was rapid elimination (within 1–4 h) of target cells after transfer into immune mice, and both CD62Lhigh and CD62Llow memory CD8 T cells were able to kill rapidly in vivo. Strikingly, when directly compared on a per cell basis, memory CD8 T cells were only slightly slower than effector cells in eliminating target cells. These data indicate that virus specific memory CD8 T cells can rapidly acquire cytotoxic function upon re-exposure to Ag and are much more efficient killers in vivo than previously appreciated.