Availability of IL-2, important for the proliferation and survival of Foxp3+ T Regs, is crucial for controlling Treg expansion during malaria as shown by increased Foxp3+ Tregs and uncontrolled parasite replication in mice infected with P. chabaudi AS or P. yoelii after treatment with an IL-2-anti-IL-2 mAb complex (6, 7, 26). This evidence concerns the gene IL2 and malaria.