Anti-CD25 mAb treatment impairs oral tolerance in normal mice. C57BL/6 mice were injected intraperitoneally with either a control rat mAb (□) or a depleting anti-CD25 mAb (▨) on days –10, –7, –3, and 0, with respect to day 0 of DNFB sensitization as illustrated in Figure 1. Mice were fed either vehicle or DNFB, sensitized, and ear challenged with DNFB. Ear-swelling responses were determined at 48 hours after challenge.