Fig. 4.

CD25⁺ foxp3⁺ Treg cells provided help to IgA B cells via TGFβ. Splenic IgD⁺ B cells (2.5 × 10⁶) from B6 mice were cultured with 1 × 10⁶ flow sorted CD4⁺foxp3⁺ T cells or 1 × 10⁶ CD4⁺foxp3⁻ T cells in the presence of 20 ng/mL TGFβ or 10 μg/mL anti-TGFβ mAb in the plate coated with 5 μg/mL of anti-CD3 and 10 μg/mL soluble anti-CD28 mAb. B cells were stimulated only by the activated T cells. (A) Supernatant was collected at day 5 and IgA was measured by ELISA. (B) B cells were re-isolated at day 3 and RNA was isolated from B cells for determination of AID using RT-PCR. One representative of three experiments is shown.