IL2 and infection: We not only make use of recombinant IL-2:anti-IL-2 complexes (IL-2C) to boost thymic-derived Treg populations in vivo prior to infection of BALB/c mice but also adopt two strategies for Treg depletion in both BALB/c and C57BL/6 genetic backgrounds, through the use of transgenic DEREG25 and Foxp3.LuciDTR mice.26 These tools permitted us to assess the impact of Treg depletion to differing degrees, at different stages of infection, and in contrasting genetic strains.