Figure 4: Antagonism of memory helper function by SEB is longlasting. BALB/c mice were primed with a mixture of TNP-RGG plus OVAp adsorbed to alum. After 26 weeks, the memory mice were injected with either PBS or SEB. At the indicated time period (Interval), the mice were challenged with an injection of TNPOVA. Splenocytes were collected 5 days after the challenge and (A) IgM and (B) IgG-producing B cells were measured using a TNPspecific ELISPOT assay. In both figures, the far right group represents control mice that were not primed but were challenged with TNP-OVA to initiate a primary Ab response. Each point represents data collected (based upon day 0 administration of SEB or PBS) from 3 independent experiments with the total number of mice indicated in parentheses. Data was analyzed by Two Way ANOVA. IgM values were not significant over time or between SEB and PBS treatment groups. IgG values were not significant over time but were significant between SEB and PBS treatment groups (p <0.001).