The 1° effector OT‐I cells also exhibited significantly reduced function and terminal differentiation (as measured by GrB and KLRG‐1 expression) within the spleen compared with the 2° effector OT‐I cells during secondary infection (Figure 5d), and compared with counterpart 1° effector OT‐I cells generated during a first primary PbA‐OVA infection (Figure 5e). Here, KLRG1 is linked to infection.