CD28 and infection: Total MLN cells re-stimulated with α-CD3 resulted in significantly reduced production of IL-13 by CD28−/− mice at day 9 post-infection (Fig. 1E) and was similar at day 12 (Fig. 1F) compared to wild-type mice, a cytokine crucial for worm clearance [27], [28], [39], [42], [45].