Composition 8203 promotes systemic dissemination of the Treg cells expanded in DLN. (A) OVA-in-8203 expands KJ1-26+ Treg cells in nondraining lymph nodes (“NLN”) and the spleen (“SP”). Data are mean ± SD of six (NLN) or eight (SP) experiments. *p ≤ 0.01 and **p ≤ 0.04, for absolute KJ1-26+ Treg counts in NLN and SP, respectively, in the OVA-in-8203 treated versus any other group (one-way ANOVA). (B) NLN and SP have a smaller fraction of proliferating KJ1-26+ T cells than does DLN. Data are mean ± SD of four experiments. *p ≤ 0.0002 and **p ≤ 0.0004, for % Ki67+ KJ1-26+ Treg and Teff cells, respectively, in DLN versus in NLN and SP (one-way ANOVA). (C) FTY720 (“FTY”) blocks dissemination of OVA-in-8203-expanded Treg cells. The model was injected with OVA-in-8203 either alone (“−FTY”) or with FTY (“+FTY”) on day 5, and cell counts were analyzed on day 8. Data are mean ± SD of four experiments. *p ≤ 0.012 (two-sided t test). (D) Percentages of DLN-derived KJ1-26+ Treg and Teff cells in NLN and SP (“% from DLN“) were calculated from data in C as follows: % from DLN = (count obtained without FTY − average count obtained with FTY) / count obtained without FTY × 100%. *p ≤ 0.001 (two-sided t test).