Figure 3: SEB interferes with secondary humoral responses in memory mice. BALB/c mice were immunized with a mixture of TNP-RGG plus OVAp adsorbed to alum (10). After 26 weeks, the immune “memory” mice were injected with either PBS or SEB, as indicated. After an additional 48 hours, the mice were challenged with an injection of TNP-OVA (20). Splenocytes were collected 5 days after immunization and IgM (gray) and IgG (black)- producing B cells were measured using a TNP-specific ELISPOT assay. The top two groups represent control mice that were either not primed or primed with only TNP-RGG to promote memory B cell development, respectively. Both control groups were challenged with TNP-OVA. Data are representative of two independent experiments.