Fig 3.

Virus-specific CD8 T cells isolated from LCMV clone 13-infected donor mice on day 8 p.i. can form memory in infection-free recipient mice. (A) Experimental design. Ly5.2⁺ CD8 T cells were purified from day 8 clone 13-infected mice and adoptively transferred to day 8 Arm- or day 8 clone 13-infected recipient mice. In each experiment, the same number of CD8 T cells was transferred to each recipient mouse, with between 2 × 10⁵ and 3 × 10⁵ donor D^bGP33⁺ CD8 T cells transferred to each recipient per experiment. Donor virus-specific CD8 T cells were examined on days 5, 15, 30, and 60 p.t. in recipient mouse spleens. (B) Representative fluorescence-activated cell sorter plots of CD44^hi D^bGP33⁺ day 8 clone 13 → Arm-infected and day 8 clone 13 → clone 13-infected recipient mice on day 30 p.t. The cells are gated on live CD8⁺ Ly5.2⁺ T cells. (C) Mean fluorescence of CD127 and PD-1. The gray histogram in each plot is gated on CD8⁺ CD44^lo naïve T cells. (D) Frequency of PD-1^hi and CD127⁺ CD8⁺ DbGP33⁺ T cells on day 60 p.t. (E) Mean fluorescence of CD127 and PD-1 on days 5, 15, and 30 p.t. Light blue, endogenous Arm response; dark blue, clone 13 → Arm transfer; red, clone 13 → clone 13 transfer; pink, endogenous clone 13 response.