Blockade of PD-L2–RGMb interaction reduces the initial expansion of antigen-specific T cells after intranasal OVA administration. (a) Experimental protocol for Fig. 9. Mice received DO11.10 T cells on day 0 and OVA i.n. The number of KJ1-26⁺ cells in mediastinal LNs was determined on the indicated days. (b) Mice treated with RGMb mAb 9D1 or control mAb on day −1 received 5 × 10⁶ DO11.10 T cells. Left, TCRβ⁺ KJ1-26⁺ CD4⁺; Right, FoxP3⁺ TCRβ⁺ KJ1-26⁺ CD4⁺ cells. For each group, mediastinal LNs of 3–5 mice were combined; data are representative of two experiments. (c–e) Mice received 2 × 10⁵ DO11.10 T cells after (c) RGMb mAb 9D1 or control mAb; (d) RGMb mAb 9D1, PD-L2 mAb 3.2, or control mAb; (e) PD-L2 mAb 3.2 or control mAb. (f) WT DO11.10 T cells were transferred into WT or PD-L2^−/− mice; (g) WT or PD-L2^−/− DO11.10 T cells were transferred into WT mice. (h–j) Mice received 2 × 10⁵ DO11.10 T cells after (h) PD-L2 mAb 2C9 or control mAb; (i) PD-L1 mAb 9G2 or control mAb; (j) PD-L2 mAb 3.2, PD-1 mAb 1A12, or control mAb. The number of KJ1-26⁺ T cells in mediastinal lymph nodes on day 5 (h–j) was determined by flow cytometry. (b–d) Each point represents a pool of LNs from three mice. Data are representative of two to four experiments. (e–j) Each point represents the mean and SEM of KJ1-26⁺ T cells in LNs of two or three groups of two mice each. Data are representative of two experiments. **, P < 0.01; ***, P < 0.005, two-tailed Student’s t test.