Fig. 3.

Increased expansion and effector differentiation in the absence of Treg is IL-2–dependent. (A) CD45.1⁺ OT-I T cells (2 × 10⁶) were transferred to anti-CD25 or isotype-treated C57BL/6 mice immunized or not with OVA/QuilA at the time of transfer and additionally administered anti–IL-2 (JES6.1 plus S4B6) or PBS, as indicated. Seven days later, spleens were collected and the total number of OT-I T cells determined by FACS counting assay. (B) CD45.1⁺ OT-I T cells were transferred to anti-CD25 or isotype-treated nTx 11c.OVA mice administered either anti–IL-2 or PBS. Three days later, spleens were collected and the total number of OT-I T cells determined by FACS counting assay. (C and E) CD45.1⁺ OT-I T cells were transferred to DEREG or nontransgenic mice treated or not with DT, anti–IL-2, or PBS and immunized with QuilA at the time of transfer. Seven days later, spleens (C) were collected and the total number of OT-I T cells determined by FACS counting assay and serum IL-2 determined by ELISA (E). (D and F) CD45.1⁺ OT-I T cells were transferred to C57BL/6 mice treated or not with anti-FR4 and anti–IL-2 and immunized with OVA/QuilA at the time of transfer. Seven days later (D), spleens were collected and the total number of OT-I T cells determined by FACS counting assay and serum IL-2 determined by ELISA (F). (G) C57BL/6 mice were treated or not with anti-CD25 or anti-FR4. DEREG mice were treated with DT and 7 d later serum collected and IL-2 measured by ELISA. (H) CD45.1⁺ OT-I T cells (2 × 10⁴) were transferred to anti-CD25 or isotype-treated C57BL/6 mice administered either anti–IL-2 or PBS and immunized with OVA/QuilA at the time of transfer. Seven days later, spleens were collected and the total number of OT-I T cells determined by FACS counting assay. Data are pooled from at least two separate experiments and each datapoint portrays an individual mouse.