Figure 3.

Loss of GFP expression discriminates a subset of differentiated T cells that are cytotoxic and produce IFN-γ. (A) Seven days postvaccinia infection or postimmunization with allogeneic P815 cells, CD8⁺ T cells from PELs were sorted into GFP⁺ and GFP⁻ cells and tested for lysis of vaccinia-infected MC57G (Left) or allogeneic P815 (Right) target cells. Results from two T-GFP mice for each method of immunization are shown. E:T ratio, effector-to-target ratio. (B) Mice were challenged i.p. with vaccinia virus, P815 cells, or SEA. After 7 days, PELs were tested for antigen (Ag)-specific intracellular IFN-γ production as described in Materials and Methods. Gated CD8⁺ cells from one representative mouse (of three tested with similar results) for each method of immunization are shown.