Serum cytokine levels after treatment with wild-type and mutated C215Fab–SEA fusion proteins in TCR Vβ3 TG mice. Mice were injected one, two, or three times (1×, 2×, and 3×, respectively) with Fab–SEA and Fab–SEA D227A and serum levels of IL-2, TNF-α, and IL-6 were analyzed after 2 h and IFN-γ after 4 h. Serum levels of IL-2, TNF-α, and IFN-γ are in units/ml, and IL-6 levels are in pg/ml.