Figure 4. Murine CD4⁺ iT_SCM cells possess high proliferation ability.

(a) Cell division of CD4⁺ T cells after stimulation with OVA-DCs in vitro assessed by CFSE-dilution assay. Naive CD4⁺ T cells, T_EM, and T_CM cells were isolated from immunized Rag2^−/− OT-II mice, and iT_CM, and iT_SCM cells were generated from in vitro activated Rag2^−/− OT-II CD4⁺T cells. These cells were CFSE labelled, then stimulated with OVA-DCs for indicated periods. CFSE profiles and the fraction of CFSE^lo proliferated cells are shown (n=3). (b) In vivo expansion of iT_SCM and other type of CD4⁺ T cells after antigen restimulation. CD45.1⁺CD4⁺OT-II naive T cells, T_EM, T_CM cells, CD62L⁺ cells, iT_CM and iT_SCM (2 × 10⁵) were transferred into CD45.2⁺ mice, followed by OVA/IFA immunization. Three days later, cell numbers in the spleen and LNs were counted (n=5 per group). (c) In vivo expansion of CD4⁺ iT_SCM cells under homoeostatic conditions. CFSE-labelled 5 × 10⁵ cells were injected into the sublethally irradiated recipient mice, then 20 days later, T cells were isolated and analysed CD44/CD62L expression and CFSE profiles. The percentage of CFSE^loCD44^loCD62L^hi fraction for iT_SCM cells or naive T cells, and that of CFSE^loCD44^hiCD62L^hi fraction for T_CM and iT_CM cells as well as the total cell numbers recovered from the spleen and LNs are shown. **P<0.01 (one-way ANOVA (a–c)). Data are representative of at least two independent experiments. Error bars show s.e.m.