Figure 5: SEB-mediated antagonism of memory helper function is dependent upon Fyn kinase. Recipient BALB/c mice were primed with TNP-RGG adsorbed to alum. At 13 weeks, memory CD4+ T cells from donor DO11.10 or DO11.10 × Fyn-/- mice CD4+ were injected into the immune mice and 24 hours after adoptive transfer the mice were injected with either PBS or SEB. After an additional 48 hours, the mice were challenged with an injection of TNP-OVA. Splenocytes were collected 5 days after immunization and IgM (gray) and IgG (black)-producing B cells were measured using a TNP-specific ELISPOT assay. Control mice were primed and then challenged but did not receive any donor cells. Data are representative of three independent experiments.