Figure 4.

Ag curtailment decreases 2° memory CD8⁺ T cell numbers and changes 2° memory CD8⁺ T-cell phenotype. (A) Briefly, 5 × 10² Thy1.1 naïve and 1 × 10⁴ 1° memory OT-I cells were mixed and injected into naïve Thy1.2 hosts (n = 8/group) prior to infection with 1 × 10⁷ CFU att LM-OVA. In total, 16 h later, one group of mice was given ampicillin in the drinking water for 2 days. (B) Bacterial titers in spleen (CFU/total organ) and liver (CFU/g) were determined 2 days p.i. (n = 3). Kinetics of (C) the total OT-I cell response, (D) the 1° OT-I T-cell response (left panel), and the 2° OT-I T-cell response (right panel) in PBL. Numbers show mean±SEM (n = 5). (E) Peak frequencies of the 1° OT-I cell response (left graph) and the 2° OT-I T-cell response (right graph) in PBL (mean±SEM). (F) 1° (left graph) and 2° (right graph) memory OT-I cell frequency in PBL (mean+SEM). (G) PBLs of individual mice (n = 5) were pooled and phenotype of 1° (upper panel) and 2° (lower panel) OT-I cells was analyzed. The experiment was repeated twice with similar results.