Fig. 1 |. CD8⁺ T cells can undergo seemingly unlimited bursts of proliferation if rested between stimulations.

a, CD45.1⁺ VSV/N_52–59-specific memory CD8⁺ T cells were iteratively sorted, transferred to CD45.2⁺ mice, and then boosted three times per mouse with 60+ days between each of three heterologous immunizations. The graph shows the percentage of total lymphocytes in blood that are comprised of transferred CD45.1⁺ iteratively boosted cells (red) or newly generated CD45.2⁺ recipient H-2K^b/N_52–59-specific cells (blue). N-tet⁺ = H-2K^b/N_52–59-tetramer. b,c, As in a, except boosting was carried out at 28–34-day (b) or 7-day (c) intervals. Similar results were observed in trailing cohorts that have undergone 13, 21 or 31 (≥60-day interval), or 15 stimulations (28–34-day interval). c is representative of two experiments with similar results with n = 4 at 3° and n = 3 at 6° and 9°. Error bars show average and s.e.m. For flow cytometry gating strategies, see Supplementary Fig. 1. For exact number of mice at each time point in a,b, see Supplementary Table 1.