Treg control effector differentiation by modulating IL-2 homeostasis under immunogenic, but not steady state conditions.

<p>A) Non-transgenic (non-Tg) and 11c.OVA mice were injected with αCD25 or isotype-control mAb (iso) and 3 days later 2×10⁶ CD45.1+ OT-I T-cells transferred with or without CpG administration. Additional αCD25 or isotype-control mAb were administered every 3 days after the initial injection. 7 days after OT-I transfer, blood was collected and serum prepared. Serum IL-2 concentration was determined by ELISA. Dotted line indicates detection limit. B-D) Non-transgenic (non-Tg) and 11c.OVA mice were injected with αCD25 or isotype-control mAb (iso) and 3 days later 2×10⁶ CD45.1+ OT-I T-cells transferred with or without CpG administration as indicated. αCD25 or isotype-control mAb was administered every 3 days throughout the experiment. In addition, mice were administered either PBS or IL-2 blocking antibodies (JES6.1/S4B6 combined) daily. Seven days after OT-I transfer, inguinal LN (ILN) and spleens were collected and the total number of OT-I (CD45.1+CD8+Vα2+) T cells and the total number of IL-2-producing OT-I T cells determined using a FACS-based counting assay and ICC. Data portray values of individual mice pooled from at least 2 independent experiments.