Figure 5. Memory differentiation is impaired without stable DC-T cell contacts.

(a, b) Purified CD11c⁺ DCs were pulsed with 10 μM control-peptide (or no peptide), 1C or 100C and injected into the right footpad of recipient mice (in A, peptide depleted C57BL/6 recipients, in B, OT-I recipients) with LPS. 5 ×10⁶ P14 T cells were injected iv 18h later. At d30+ post-T cell transfer each mouse was infected iv with 10³ p.f.u. LCMV Armstrong, the spleens harvested at d5 p.i. and IFN-γ was stained by ICCS after a 5h ex vivo stimulation with (+) or without (−) 1μM C-peptide at 37°. (A) C57BL/6 recipients were treated at d-10, -7 and -4 with high dose M-peptide to deplete them of Ag specific cells. Upper graph shows a summary of CD8+ IFNγ+ and lower graph shows representative flow cytometry. (N=3 expt, 3-5 mice, per condition; mean ± SEM). (B) Recipients are OT-I Rag1−/−. Upper graph shows a CD8+ IFN-γ+ and lower graph shows representative flow cytometry. Of note, in the OT-I recipients there were occasionally animals with extreme splenomegaly and expansion of lymph nodes (in all conditions) which were excluded from analysis in all settings. (N=3-5 expt, 4-7 mice per condition, mean±SD per mouse).