Figure 1. TL negatively affects memory generation of CD8αβ⁺ T cells.

(a) WT or TL^- mice were orally infected with 1 × 10⁹ ActA^- Lm-OVA. 30 days p.i., splenocytes (SPL) and IEL were isolated for IFN-γ intracellular staining and CD8α cell surface staining after ex vivo re-stimulation with OVA_257-264 peptide. Graph depicts pooled data ± s.e.m.. (b) 5 × 10⁴ naïve Ly5.1⁺ CD8⁺ OT-I cells were adoptively transferred into Ly5.2⁺ WT or TL^- recipients. One day after transfer, mice were orally infected with 1 × 10⁹ ActA^- Lm-OVA. Donor OT-I cells were tracked in the spleen and IEL 2 months p.i. Graph depicts pooled data ± s.e.m.. (c) 1 × 10⁶ naïve Ly5.1⁺ OT-I cells were transferred into WT or TL-Tg recipients. One day after transfer, mice were orally infected with 1 × 10⁹ ActA^- Lm-OVA. The donor OT-I cells in the spleens and IEL were tracked two months p.i. Graph depicts pooled data ± s.e.m.. (d) 5 × 10⁴ Ly5.1⁺ naïve OT-I cells were transferred into C57BL/6 mice which were subsequently immunized i.v. with 5 × 10⁵ OVAp-loaded DCs generated from bone marrow cells (BMDC) of WT or TL-Tg mice (top). Alternatively, OT-I cells were primed in vitro with TL negative APC or APC transfected with TL and then transferred to B6 recipients (bottom). Memory OT-I cells in the spleen were analyzed 2 months after DC immunization or after transfer of in vitro activated OT-I cells. Graph depicts pooled data ± s.e.m.. (e) Spleen or mLN DC were sorted based on the CD11c and MHC II expression and assessed for TL expression by flow cytometry. (f) Freshly isolated SPL or mLN DC were activated with CpG for 1 d and then analyzed for TL expression. * P < 0.05 and ** P < 0.001 (unpaired t-test). All data are representative of three independent experiments.