Figure 2.

Recall LLO_91–99–specific T cells are characterized by higher peptide sensitivity than primary effector CTLs. Short-term T cell lines (A and B) and ex vivo T cells (C and D) were assayed in CTL assays (A and C) or stained for TCR expression (B and D) as described in Materials and Methods. (A) T cell lines were generated by short term in vitro peptide stimulation for 5 d from primary day 7 (□) or reinfected day 5 (○) mice, as described in Materials and Methods, and the percentage of specific lysis in the presence of different concentrations of LLO_91–99 peptide was determined by standard ⁵¹Cr-release assays using P815 (H2^d) target cells. (B) TCR-α/β surface expression of the two T cell lines shown in A. (C) Cr-release assays as in A but with cells isolated directly ex vivo from primary and recall infected mice and enriched for CD8⁺ T cells. Four mice per group, lines show mean values, symbols show data of individual mice. (D) TCR-α/β surface expression of LLO_91–99–specific, primary, or recall T cells isolated directly ex vivo.